A few years ago I started playing with a laser cutter in a “maker space”, and the thing that I have had the most luck with was chain guards for my bicycles, to help keep my pants slightly cleaner.  I made one out of mirrored acrylic which looks Very Flashy, but the acrylic is not that durable.

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During Covid, I lost access to the maker space, and needed a new chain guard for one off my bikes, so I went and ordered one in 3mm acetal from Sculpteo, and it has worked very well.

I don’t recall if I sent them a PDF or a SVG, but it was one of the two.

Anyhow, my chainring was creaking, some of the chainring bolts were working loose, so this seemed like a good time to take it all apart, tighten things up, and take some pictures.  Obviously the chainring needs some parts to hold it together, and these are shown here.

First, mounted on the bike.  The gap for the crank arm makes life very, very easy, compared to the aluminum ones that usually come with bicycles.  

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This is my spare copy (I ordered two, shipping for two was as high as shipping for one).  Notice all the little spacers in the waste section in the center; those will be useful later.

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Here is the old one, removed, with screws and washers still in place, and all the spacers in the box below.

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To reinstall, use tape to hold the screws and washers in place, then put a pair of spacers (each is 3mm) on the backside.

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Here I’ve tilted it the other way so you can see the spacers.

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Insert the long skinny screws through the center holes in the chainring bolts, and spin the little nuts on the backside so the screws won’t come out, remove the tape, and crank them down pretty tight (because acetal is tough, unlike acrylic).

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To the Belmont Select Board,

I am writing to support the proposed parking-protected bicycle lanes on Concord Avenue. I believe these will make it safer and more comfortable for most people to bike on Concord Avenue and attract more people, especially students, to use a bike instead of arriving at the schools by car. I have biked on Concord every working day, year-round for the last seven years, so I know the road well and especially its risks from a biking point-of-view.

Parking protected lanes would increase safety in at least two different ways: removing risks from swerves (either bike into car or car into bike), and dooring risk. Some dooring risk remains, but the left (driver’s side) door is the one most frequently opened from a parked car, so riding on the right side of a parked car is safer. Riding on the right side also means that in the event of an abrupt door opening, all the other obstacles are stationary and will never be a large truck with exposed deadly rear wheels.

Obviously, having surer separation from traffic makes the ride more comfortable. With luck, more middle and high school kids will use these lanes to bike to/from the middle and high schools instead of driving or bothering their parents for a drop-off by car, thus reducing traffic jams during the school rush.

These new lanes will inconvenience some people. Turning onto Concord from a side street will be more difficult because it will be somewhat harder to see oncoming traffic. Cyclists whose primary goal is speed may find themselves less able to pass other, slower, cyclists (in Cambridge and Somerville, this is just how things are at rush hour, so I have ample experience as both delay-er and delay-ee). These problems, however, are of a different and lesser category than personal physical safety.

We should also recognize that some of these abutter convenience compromises are themselves the result of other compromises; if we did not care so much about minimizing the number of lost parking spaces, we might instead construct a bidirectional protected lane (using Jersey barriers, perhaps) on the north side of Concord Ave along Clay Pit pond and the high school. This would not only leave the south-side abutter experience unchanged, it would also provide easier passing for higher-speed cyclists, remove turning risks from the south-side streets (either right-hooks from Concord onto the side street, or T-bones from the side street onto Concord), eliminate the right-side door-zone risk, and provide a guaranteed-available route for emergency vehicles (wide bidirectional bike lanes are used for this purpose around the world, including even in Cambridge, I have video). To be blunt, a whole lot of advantages, including safety advantages, were traded away for the purpose of preserving parking. We like parking a whole darn lot here in Belmont, otherwise we’d make different choices.

One place where the current plan is particularly lacking, and may want future improvement, is on the stretch of Concord approaching the Post Office and underpass. There, a bidirectional north-side lane would be a lovely safety improvement, but I don’t know how to reconcile that with the obvious need for short-term parking, especially handicapped access parking. It is, however, the most dangerous and least comfortable stretch of Concord (the very same short-term parking that is so necessary, also creates a dooring hazard, and the underpass is an abomination from the point-of-view of comfortable, safe biking). I have some hope that the Alexander Avenue tunnel under the railroad tracks, when completed, will provide a suitable alternative for safe, low-stress bicycle access to the Winn Brook neighborhood and Belmont Center from the high and middle schools.

Assuming we create these protected lanes, one detail that would help is to check the pavement for flaws and irregulaties, and correct those. I’ve recently looked at the road where the protected lane will be, and what I could see looked generally okay, but there’s a few spots that could be improved. Potholes are a surprisingly common cause of bicycle crashes, especially for less-experienced riders.

David Chase

So, I ride a cargo bike most of the time, have for about 15 years and 38,000 miles, I sometimes forget that lots of people only have experience with “normal” bikes (or worse, only with a car), and just work with that knowledge.  And I end up explaining this stuff, or parts of it, over and over again to people who think they understand what a “bicycle” is and what its “limits” are.

Read the rest of this entry »

I tried to take pictures of each step along the way.  The goal here is to make a durable, “washable” (soak in boiling water, or alcohol; I don’t think detergent is good) mask that filters very well and also breathes pretty easily, seals well, will not collapse if you breathe hard, and muffles your voice somewhat less.  I tried making one of these with no fabric, just filter material, and that is not strong enough to last; the interior layer is necessary (and feels nicer on your face).  The filter media I use here filters well — it looks good on paper, and when the west coast smoke blew into Boston, it stopped the smoke smell (it does not stop smaller smelly molecules).  For reference, from that paper, here’s the graph of filtering effectiveness and breathing resistance (which is high).  It’s the pink lines at the top, just under never-washed N95:

Mask material reuse

The difference between this material, and medical N95, is that those use electrostatic charge, which is magically good till it wears off because you washed it (note that this chart quits at half a micron, so it is not the whole story).  Not using magic electrostatic properties means that the filtering survives exposure to alcohol, but also that the breathing resistance is much higher.  Nonetheless, I manage, most other people should as well.

The mask is shaped like a duck bill, beware, and there’s a tradeoff between area (ease of breathing) and volume (rebreathing of CO2).  The pattern itself is parameterized, so that you can adjust its size somewhat for your own personal face and your own personal preferences for ease of breathing vs rebreathing CO2 (we have varying lung sizes) vs ridiculous appearance; I put a program on the web to do this; it creates the pattern in two halves, which you print on card stock, cut out, and tape together (as seen below).  I’ll update it from time to time; notice how the pattern below printed “elastic” in the wrong place (fixed), labels one of the darts wrong, and I really wish it had a QR code that would let someone reproduce the mask without retyping parameters.

This is the 4th iteration of a design that started with one from the UF School of Anesthesiology.


  • Cummins Filtration EX 101.  This comes in packs of 50.  I can send smaller quantities to friends and family, the rest of you have your own friends and family.
  • Heat shrink tubing for capturing wire ends in the nose wire, and for holding the coffee stirrer nose brace together.
    2:1 shrink ratio, 90 degrees C activation, 1/8”, 3/16”, 1/4” (I use NTE clear from Digikey).  You can use tape for the brace joints, and if you have some other way of making a nose wire, you don’t need this.
  • 5.5” Coffee stirrers (Amazon link) for the nose brace.
  • Wire for nose wire (I use 19-gauge copper wire that I rescued from the side of the road after a lawn mower ran over a phone wire bundle).  I did once try 19-gauge stainless wire from the hardware store, it is not comfortable.
  • Cord/shoelace and cord lock for neck strap.
  • Elastic for head band.
  • Fabric — I use linen or hemp for the interior, whatever for the exterior.  Goal is both should breathe easily (the filter does the filter work), interior should be strong enough to deal with cords and braces, exterior (which is actually optional) should protect the filter from abrasion, perhaps have an appearance.  So while you can use old T-shirt for the exterior, it’s probably wrong for the interior because it is too stretchy.

Photos of steps (high-res album version):

Nose wire first.  This is 9.5 inches of copper wire, alternately use 2 pieces 4.5 and 5.5 inches long with the longer wrapped around the ends of the shorter.  To bind it all together, use heat shrink tubing, fold in a piece of fabric, then apply an iron, blast a few times with steam.  It will stick slightly to the fabric, which is why you wrap it in fabric because that is better than sticking to the iron or the ironing board.

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After doing the ends, also.

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Filter media and pattern.

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Pattern just fits the filter media, this is by design.  For the filter, don’t bother with any flaps or tabs, and don’t do the darts yet either.

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Foreshadowing: this is the ultimate destination of the nose wire.

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Pattern traced.

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Pattern cut, precisely around the face, with slop around chin and nose, to be trimmed later.

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Pattern on the interior layer, which gets all the tabs, flaps, and alignment marks for the elastic and cords.

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Cut, again with some slop.  The flaps will fold down, and then iron to make it easier to sew.

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Exterior layer, which is a used tie-dye T-shirt.  No marking for cord attachment or tabs. Cut this with a fair amount of slop.

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And cut:

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Here’s an extra bit of more T-shirt to go inside the nose-wire flap, to help cushion the nose.

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Sewing the nose wire flap.  This is the only place where pins are appropriate, once the filter is in the mix, use clips instead because holes in the filter are to be avoided as much as possible. I have access to nice clips because my wife sews very well and my mother-in-law is a fiber artist (it was her that sent me the original pattern from UF) but bulldog clips get the job done and I have also used those.

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Sew along the bottom to leave a channel.  This will get narrower when the filter and exterior are sewed to this.

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Trim away the excess.  It doesn’t need to be super pretty, nobody will see this.  The nose wire goes inside, just shown here on the outside to show how it will be positioned.

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And with the pockets sewed.  These will also be sewed across the bottom, later.

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Recipe for stacking the layers.  This part is important, I copied it from older instructions for another pattern.  Steps will appear below.  The filter “outside” has more dimple-y dimples, bright light helps for telling them apart.

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First put the interior together, using clips to get the cords positioned right.

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Align the exterior layer on top; it’s good to get the patterns aligned for later, but this one is mostly for show, and excess will be trimmed soon.  One problem with too much extra fabric is it gets in the way of aligning the filter (one top) and the interior layer (own the bottom), which is what really matters.

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Carefully position the filter.  Goal is that its face edge (the part that curves up, around, and down from left to right) is well-aligned with the interior layer at the bottom.  Apply lots of clips to keep everything from shifting.

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One big stitch from lower left around the top to lower right.  I take my time.  It just now occurred to me, if I had no machine, could I sew this by hand, and I think the answer is “yes”.  It would be tedious, but it is entirely at the edge and I think you could whip stitch it, just fold the exterior up and on top and bind it all together.  I might start in the middle and then go to one edge, then the other.  The pockets and nose flap would be more work, but you can use more fabric there and take your time, that’s just sewing fabric.

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Use fingers to keep everything moving together, don’t want cords to shift.

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Done, from the top of the stack. (Links to high-res)

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Done, from the bottom of the stack. (Links to high-res)

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Prepare to flip interior around.

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Flipped, looking at interior and cords.

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NOW use the pattern to put the darts on the mask.  Align the pattern with the filter, which is hidden under the exterior in this photo.,

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I sew it somewhat more generously than the mark, probably ought to reflect that in the pattern.  Note that the clean side of the sewn dart goes against your face, for better comfort and better seal.  Design of this mask, most people won’t see the underside of your chin anyhow.

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Both darts done.

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This is the relatively tricky part and is probably subject to some further improvement.  The two chin edges need to be brought together, and then sewed.  I’ve left the pattern un-cut in the nose because there is always some imprecision here and this lets me even things up at the nose.  The clip here marks where the sewing stops.

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Finish the chin with a stitch across the darts and the center.

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After sewing the chin, need to sew the nose.  The mark on the pattern shows where.

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After sewing across the nose, clip off the excess.

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Next need to make the nose brace.  This is pretty much by eyeball, and I got the short one in the nose too long the first time.  I cut the coffee stirrers to length with some wire clippers, then use sandpaper to take off the sharp parts.

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To join the coffee stirrers together I use 1/4” heat shrink tubing.  I’ve also used gaffers tape, probably fabric adhesive tape would also work.  Again, wrap in scrap fabric and use a steam iron to shrink.

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I use two layer of heat shrink tubing — this is the completed brace.

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To fit, anchor the ends but do not fit the nose.  Put the not-in-nose angle in the chin, then push into place.  If this seems impossible, shorten as necessary.  If you need to shorten the center, either pull it apart or razor off the tubing.

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Brace in position.

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On my face. This is a lot of mask, I am trying to figure out how to fit a restraining thread through the middle of the bill to reduce its volume, that will still allow me to remove/replace the brace if I want to,  To wash this thing, take out the nose wire and brace, and either soak in boiling water or alcohol.  I tried a washing machine once, and to me it seemed to increase the breathing resistance until I washed it again in boiling water.  I’ve used one of these (not this one, but very similar design) to ride a bicycle 6 miles home from work, when we had the nasty smoke blow in from across the country.  I did not ride 100%, but I rode fast enough.  I also used a smaller one for a few hours on an airplane — it would not be adequate for exercise, but worked fine for sitting.

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No I didn’t write this because of the IPCC report, I don’t write that fast, been working on it for a while.

Something that has become more and more clear to me over the last few years is that there’s no single silver bullet for decreasing greenhouse gas emissions from transportation (aviation, shipping, rail, and particularly cars and trucks), which is now the largest US source of GHG emissions.  Partly this is because we’ve spent decades making ourselves dependent on fossil fuels, and partly this is because we can only change things so fast even if we want to.  And, because we’ve dithered for so long (with the obfuscating assistance of the fossil fuel industry and their useful political idiots), we don’t have much choice but to do everything we can, immediately, to cut emissions. If you think, “maybe GHGs are not a problem, I’m sure we’ll adapt”, this is not for you, stop reading, go away, you’re an idiot, no I will not approve your comments.  This is instead, do not be so focused on your own favorite silver bullet that you dismiss other things that would help, because anything that is roughly cost-effective would help, and we need all the help.

So, where are we now?  Right now, the median vehicle trip is only 5 miles (my calculation, from ORNL data), but that is only about the 30th percentile commute, which for a lot of people is a a 5-days-per-week round trip.  And short trips don’t cover a lot of miles; the average length of all trips (not just commutes) is 10 miles, but half the miles traveled occur in trips of up to 19 miles (this is not intuitive, I made a fake distribution in a spreadsheet so I could verify I had not made an error).  And the trips up to 5 miles only (cumulatively) account for about one-eighth of all miles traveled in cars and trucks.  So, bicycles and micromobility by themselves are not enough.  On the other hand, biking works for a whole lot of people, right now, all weather, e-bikes solve the hill problem and help with the range problem, and biking and micro-mobility could do a lot to improve use of long-haul transit, and reducing car use in dense places (cities) does a lot to make increased density not just palatable, but even attractive.

We’re producing electric cars, yes, but right now they’re only 2% of all new cars in the US (that’s new cars, not all cars), and the average car on the road is 12 years old; cars sold today will be with us for a while.  If we miraculously transformed all our cars to be electric overnight, we’d also need to make the electrical grid about 15% larger than it is now — not the GHG-free electrical supply, but the total supply, generated all ways, delaying the phase-out of existing dirty generation. The non-electric cars that we drive also tend to be ludicrously bloated; that’s no help at all.

We could move closer to our work and to shopping, but moving is a pain (says a friend, “three moves equals one fire”) and the first two decades of my life I lived someplace undergoing 3% population growth every year, largely in (literal) green-field development and it severely burdened the government to keep up (in particular, to keep up with school construction; “portables”, double sessions and 45-15 scheduling were all used to deal with the problem), so there are limits to how quickly people can move around and how fast we can build infrastructure to add people to an existing city or suburb, assuming that everything else aligns to make it possible.  On the other hand, we actually did this — 3% growth per year for 20 years, it happened, over a whole Florida county (Pinellas, decades ending 1970 and 1980, see also Pasco, and Hillsborough).

It’s also worth comparing the things we think are “hard”, with what’s truly hard.  Long-haul air travel without liquid fuels?  That’s really hard.  Ocean shipping at existing scale and speed without liquid fuels?  Also hard.  And among the liquid fuels, hydrocarbons are superior; alcohol could work, but it’s less energy per gallon or kilogram when burned, never mind that biofuel alcohol production has a lot of fossil fuel inputs (these could be improved, but that’s only at the experimental stage right now)  All the other substitute fuels have similar problems — burning hydrogen itself produces no long-lived greenhouse gases, but producing hydrogen requires energy, which comes from where?  And carbon capture?  Not proven at scale, and that also uses energy, who’s going to pay for that?  And where do we put it, to be sure it will stay put?  And yes we should keep studying these things, they look really interesting, some of them will turn into wins, but they haven’t yet, we need to diversify our risks, and we don’t have time to wait.

The distinction between what we can do now — things that are proven to scale, that are done elsewhere already, that were even done here in the past — versus things that we might be able to do in the future, is important, because we need to make real reductions now, not promised reductions in a future that will arrive as slowly as our dragging feet can manage.  The problem with global warming is that it does not reverse quickly; we’re emitting CO2 far faster than the climate can come into equilibrium (oceans absorb an almost incomprehensible amount of heat) and it persists in the atmosphere for hundreds of years.  If through some miracle we zeroed out our greenhouse gas emissions tomorrow, it would still take decades (centuries?) for the earth’s temperature and all its weird-weather effects to come into equilibrium; however, any reduction in emissions now is still good because otherwise the rate of change comes even faster and the endpoint is far worse.  

So, what have we got that we can do now?  And how do we help it happen?

Not driving

Not driving, how does that happen?  Buses, trains, subways, bicycles, scooters, skateboards and walking all worked well in the past, work in other places right now, and work for many people here already.  People use them in combination, i.e., “multimodal”. New technology, for better lighting, better tires, better batteries, better materials, and better motor controls has already made these better than they were in the past. There’s no particular reason to believe that not-driving should be rare.  

It’s probably worth describing some of the parameters of these other modes, because to read what other people say, it is clear that many people don’t know how they work.

(Begin digression)

On a plain bicycle, a typical speed is in the range of 12-15mph.  Some people can cruise at 20mph, but that’s not usual case.  Anyone cruising (not sprinting) at 25mph is in exceptionally good shape.  Only top athletes cruise at 30mph.  Increasing speed comes with sweat and safety tradeoffs; higher speeds generate passing conflicts with other riders, surprise drivers (if bikes and cars share space), and yield much more unpleasant crashes.  Someone who bikes 6 miles to work at 20mph will want a shower when they arrive; they’re typically drenched in sweat.  Cruising at 12mph means that 6 miles takes 30 minutes without stops, which is generally regarded as a comfortable limit on commute length and results in much less sweat, yet still provides plenty of exercise. For congested automobile traffic on surface streets, 12mph is quite competitive, given that a bicycle can filter up to intersections instead of waiting in line (multiple bicycles also clear intersections far more quickly than cars do per “lane”, even given the reduced size of a bicycle lane).  Solo crashes at lower speeds are also much safer.  Lower speeds are safer for pedestrians; though bicycles are far safer for pedestrians than cars are, pedestrians-fatality crashes at or below 15mph are even rarer.

E-bikes come in several flavors; throttle and pedal assist, and regulated at 20mph, regulated at 28mph, and (illegally) not regulated.  Typical e-bikes come with a 250W assist, which is “you’re now very fit” at the push of a button.  The legal limit in the US is 750W, which is quite a lot of power (more than the best athletes produce continuously) and there are bikes on the road with more than that; sometimes for speed, but the ones that I know of (I know of 2) use it for hill-climbing with cargo.  There’s wacky variation among state laws, but above describes California and federal regulations (which apply to use and sale, respectively).   20mph cuts a 6-mile commute to 18 minutes, and with much less sweat.  For my commute (through a Boston suburb and Cambridge) an e-bike would handily beat driving at rush hour, and would be competitive even off-peak, but commute speed is not my only priority (I also care about exercise, have repair skills that don’t include batteries and motors, and charging at work is a hassle).  One important thing that e-bikes do is flatten hills; it may be that the shortest route traverses a hill, or the safest route traverses a hill, and on a regular bike you might choose to avoid the hill because hills are work.  But on an e-bike, no problem.

The big win for multi-modal commutes (where the default multiple modes are “walking” and “transit”) is that the alternatives are notably faster than walking.  A 10 minute walk at 3mph is half a mile.  For a bicycle, assuming a minute spent locking up, the remaining 9 minute ride at 12mph is 1.8 miles.  For a train or subway station, that increased speed puts 13 times as much area within 10 minutes of the station, so crudely, 13 times as many people can reach the station without using a car, which would add to congestion near the station and also requires much more space for parking than a bicycle does.  A skateboard is slower (9 mph) but needs no locking if you carry it with you onto the train, so an extra minute, resulting in 9 times the area that can reach the station in 10 minutes.  A skateboard, if you are capable of using one (I’m not, at least not yet) is also supremely reliable; no pneumatic tires to puncture, no chain to come off, no brakes to fail.

For multi-modal commutes, plain bicycles are typically for first-mile(s) or last-mile(s); they’re good for either, but are more of a pain to take with you on a bus or train.  Buses often have racks on the front, but if lots of people were doing bike-bus-bike commutes (where the bike travels on the front of the bus), those racks would tend to be full and you might have to wait for a bus with an empty slot, which adds unreliability.  Some trains (Caltrain, e.g.) allow bicycles at rush hour, but when you compare the human occupancy of a “bike car” with a regular car, a rider + bike take 3 times as much space, and the increased difficulty of boarding and leaving the train carrying a bicycle risks increasing dwell times at stations. Level boarding platforms would help with this — roll on/off is much easier than carrying a bike up/down steps; this is an example of how doing “all the things” can interact favorably, because we should be doing level boarding for ADA and faster boarding in general.  Most trains and subways, however, do not allow plain bicycles at rush hour, because that would cut their overall capacity and they often run full (this is definitely true for BART and MBTA).  Folding bicycles typically receive an exception, but these are sort of an all-around compromise; the nicest ones are ok bikes, but not the best bikes, the lightest is 22lbs but over 30lbs is common, so they’re a noticeable hunk of “luggage”, and even folded they take up a bit of space.  E-bikes are useful for larger amounts of first/last miles, or those that include hills, but are much worse for bike-transit-bike unless the transit is roll-on and roll-off, because e-bikes are notably heavier than plain bicycles.

A skateboard tends slower than a bicycle, but is darn near optimal for multimodal use.  They’re light and compact, and you can carry them on a bus or train anytime, and typically use them right up to the moment you step onto the train/bus, crowds and local regulations permitting.  (Local regulations may not permit, because local regulators look down on the sort of riff-raff who would use a skateboard for transportation).

E-assist scooters, skateboards, mono wheels, and hoverboards are all very, very interesting. By default these can travel at least 20mph (unclear if they’re legally regulated or not) and are also relatively easy to carry on/off transit, depending somewhat on details.  E-skateboards are probably the easiest; hoverboards and mono wheels, in my limited experience (picking them up at a demo) are somewhat more lumpy, though more compact than a folding bicycle. Traveling at 18mph on something that you take with you on the bus or train means that the 10-minute area around a train station is now 36 times larger than what you could reach walking 3 mph.  Scooters require less skill, but are heavier (27lbs, versus 17 for an e-skateboard) and a little bulkier even when they fold, though the folding scooter I saw had a nice design for carrying.

For cargo delivery, especially urban cargo delivery, e-assist “bicycles” (actual bicycles, tricycles, and quadricycles) work well for small loads.  There are tradeoffs between loading time, time spent stuck in traffic, time spent traveling back and forth for new loads, and contention for loading dock space, which can be an issue for trucks, but much less so for bicycle delivery.

There are weather issues with all of these choices, but if the goal is not-driving, a fraction of the cost of a car can still buy both a bicycle AND an e-scooter, where the bike is better for cold weather (exertion makes heat, studded snow tires deal with ice and snow) and the e-scooter is better for heat and rain (less exertion; mostly stationary posture makes a rain poncho work better, less sweaty).

Trains and subways are notable because rail can carry a boggling quantity of people.  One subway line in Boston can carry (and does carry, at non-pandemic rush hour) as many people per hour in a single direction as 10 lanes of car traffic at maximum throughput. For longer-haul commuters, commuter rail carries 42% of the total rush hour traffic into Boston.

(End digression)

Quite a lot of what we need for other modes is attention paid to the same sort of convenience that causes us to default to cars today.  So, buses and trains, if they only come once an hour, that’s not convenient — so don’t do that, arrange for them to come more frequently.  Yes, that will cost money.  Waiting for transit, what if it is raining, what keeps the weather off?  So waiting areas should have a roof, and a bit of shelter from wind, too.  When it snows, we plow roads for cars, but we don’t plow sidewalks, and often road-plowing results in sidewalks being blocked at every street intersection; if we expect people to not-drive, better make it reliably physically possible.  Buses get delayed in traffic; when multiplied by all the people on the bus, that’s a huge inconvenience, so the bus should get its own lane and be able to trigger green lights at intersections. Biking, is there a safe place to lock-up a nice bicycle?

  • Build densely.  We did this in the past, we could do it again.  Not only does this shorten car trips, it also makes alternatives feasible.  But it seems unlikely that we could add density (people) faster than 3% per year.  The goal therefore should be to make whatever growth we can work as well as possible; site it close to transit stations, site it close to bike routes that connect to nearby destinations.  Don’t create dense housing in the middle of nowhere, even if that land is cheaper.  In some cases there are problems with municipal funding — it’s common to fund the  bulk of K-12 education from property taxes, so adding people puts pressure on a town’s budget — so fix those taxes, it’s not like that’s an inherently good way to pay for schools, it’s just a thing we happen to do (and it helps preserve the effects of redlining, so it’s kinda racist, too). There are other good reasons to make this funding change.
  • Make transit nicer (a non-comprehensive list of examples):
    1. Improve subway signaling so that trains can run closer together (this will save time and make them less crowded)
    2. Buses obtain a double benefit from bus lanes; not only is the bus ride less delayed, but the buses can run more frequently (or fewer buses can provide the same level of service).  For example, if a bus lane converts a circular 30 minute route into a 20 minute route, then it takes only 2 buses to come once every 10 minutes, instead of 3.
    3. At intersections, buses should be able to request an early green so that they are least-delayed, for the same reasons.
    4. There’s a level of crowding that causes many people to avoid transit; if there is crowding, great, transit is popular, but the goal is to get more people on it, not just minimize per-rider costs, so ADD MORE TRANSIT till the crowding is reduced.  If the existing service cannot be expanded (trains are maximum length, running at minimum interval, still crowded) then add alternatives — redundant bus and bike routes for short haul, better support for carpooling for long haul.
    5. Elevators should work, and should also be easy to find and access.
    6. Clean stairwells more aggressively (so that they don’t smell).
    7. Bus stops (and train stops!) should be sheltered from the weather.
    8. Trains should use level boarding, because that is faster, easier, better for disabled people, and eases the option of bikes on trains.
    9. Trains should use electrical power (not batteries, that is not yet proven for trains at scale) because that is quieter, cleaner, and provides faster acceleration from stops which saves time.
    10. Trains should come frequently, and where possible trains and buses should have properly synchronized transfers (frequent service takes a lot of the sting out of poorly coordinated transfers, but minutes spent waiting or walking add up fast).  We have a lot of rails in place already around some large cities, we just don’t use them enough.
    11. Transit should not shut down at midnight; there are people who need it at all hours.
    12. Transit stations should have abundant, safe, and convenient sheltered bicycle parking, and perhaps also lockers for scooters and skateboards; not everyone wants to carry those with them onto the train.
    13. Train tracks should be improved so that the ride is smooth, and people riding the train can easily read or work while they ride, if they wish to.
  • Make “micro mobility” nicer.  I have many, many suggestions here, because I ride a bicycle daily to work and am well aware of all the little friction points.  Someone with daily transit experience (I had that once…) can probably flesh out my suggestions above.  But on to the bicycles and little e-things:
    1. There really, truly, needs to be safer places to ride.  That probably won’t happen until a larger number of people are biking/etc, but if you want to get people out of cars, either driving has to become a lot less pleasant (that will be ever so popular) or else not-driving has to become a lot more pleasant.  And this right here is the number one item.  Safe, separated, relatively direct and non-squirrelly bicycle routes connecting popular places.  And allow all the little e-things to use them, too — seems obvious, but some places (e.g., Massachusetts) have laws that technically ban e-assist from bike paths.
    2. Uniform sensible standards for all the e-things, so the markets are bigger.  That means, the same power limits and speed limits and where-you-can-ride and who-can-ride and what-you-must-wear rules in all the states must match.  California has good-enough rules, every state should adopt California’s standards, no, your state is not special.  Your safety objections are foolish, if you cared about safety, you’d be all over item #1, #3, #4, and #5, your state is not special, your city is not special (yes the European speed limit is better, but 20mph is not terrible).
    3. Trucks should have side guards.  This is the rule for some US municipal truck fleets, and is the rule in much of Europe.  Sideguards reduce bicycle (and pedestrian) overruns, which are deadly and horrible.
    4. Trucks (large and small, including pickup trucks) should be designed for improved visibility.  It’s been done in Europe, we could do it here.  
    5. Curbs should be rounded over.  Sharp-edged granite curbs are a gratuitous hazard in any crash (they’re also heck on car tires).  Either the sharp edge can be rounded off, or the granite can be replaced with concrete, which works fine with snowplows in Minneapolis and Chicago (you can look at curbs on Google Streetview, and I wrote to both highway departments to ask about durability and cost and they said it is fine).
    6. One-way streets by default should include a counterflow option for bicycles/etc.  Streets are often made 1-way to prevent car and truck cut-throughs in quiet neighborhoods, but bicycles and other small things are quiet and safe so need not be excluded, and benefit themselves from the safe, quiet cut-through.
    7. Bicycle parking should be abundant, easy to find, easy to use, and should include provision for oddly-shaped bicycles (tricycles, for people who lack balance; cargo bikes, for people who need to transport children and other cargo; recumbents, for people with back issues).  Some bikes are heavier than their riders can lift into upper racks; some bicycles have wide tires.  Some popular rack designs are actually terrible; those should be avoided.
    8. Bicycle parking should be sheltered from the weather, and where theft is a problem, should include anti-theft measures. For example, at the MBTA Pedal&Park bicycle parking, access requires a registered commuter card, the cages are monitored with video cameras, they are sited so that anyone walking by can see inside, and there’s a cardboard policeman at the end because studies show that helps a little (and the cost is low).
    9. At intersections, “Idaho Stop” should be the rule for bikes etc.  This is “treat stop lights like stop signs, treat stop signs like yield signs, and of course that always includes yielding to pedestrians”.
    10. At intersections, bikes etc should be allowed to proceed on the LPI (early walk signal) and on all-ways pedestrian signals, again yielding to pedestrians.
    11. Lights along bicycle commute arteries should be synchronized to bicycle speeds, not car speeds.  This will save time and also reduce sprinting at yellow lights, which is not the safest thing for either cyclists or pedestrians.
    12. Bike/etc lanes and paths should be smooth.  That means preparing off-road paths well enough that tree roots don’t tear them up in a few short years, that means any piece of a road re-designated for bicycle/etc use should have its pavement checked and fixed (the default is that it is awful).
    13. Bike/etc paths and lanes (especially the lanes) should be clean and (especially) clear of glass and other tire-damaging debris.
    14. At minimum lanes should wide enough for people to comfortably ride side-by-side.  Off peak, people often like to ride together, at rush hour people need to pass, and some bikes are wider than others.
    15. Adopt German lighting rules; requiring and standardizing lights means that they’re cheaper, ubiquitous, and annoy pedestrians and other cyclists much, much less.
  • Make “walking” nicer.  Here, walking also includes rolling, in wheelchairs and mobility scooters. And, again, my knowledge here is incomplete, this is just a start.
    1. Streets and roads should have sidewalks, and those sidewalks should be comfortably separated from the road.
    2. Roads should have crosswalks at useful intervals.  Pedestrian overpasses are not preferred because climbing stairs is work and anti-wheeled-thing and climbing ramps tends to add distance, and adding distance for the slowest mode is bad.
    3. Intersections should be designed to enhance pedestrian throughput and safety.  For example, right-turn-on-red should not be allowed any place with much pedestrian traffic (or near parks and schools where children are likely to be using the road).  Slip lanes should be avoided because they encourage hasty turns.
    4. In urban areas with lots of pedestrian traffic, sidewalks should be adequately wide for that traffic.
    5. Sidewalks should not be the default repository for random clutter and road signs; there should be a clear and unobstructed path.
    6. Where it snows, sidewalks should be plowed first.  Crosswalks should not be obstructed by snow piles.
    7. Adjacent roads should be puddle-free so that pedestrians do not get sprayed when it rains; or, there should be barriers to prevent this (a bike lane protected by parked cars is an adequate barrier; or, a wide bike lane).
    8. Urban sidewalks should have awnings so that people on foot are shielded from the worst of the weather.
    9. Crosswalks must drain properly, so that people walking step in many fewer puddles (and would you want to handle a wheelchair wheel after it had been dunked in who-knows-what?)
    10. Trucks should have many fewer blind spots, and the high front grills that are popular now in the US have practically nothing to do with actual truck utility, and should be banned.  There’s no need to design new trucks, because these regulations exist in other parts of the world (e.g., Europe) and their designs could be used here instead.
    11. Laws against jaywalking should be revised.  Some other countries do have similar laws, but they’re weaker (typically applying only “within 50m of a crosswalk/intersection”) and our laws haven’t resulted in greater pedestrian safety.  In practice their main use is to give cops an excuse to harass black people.

If we can’t stop driving, we can still drive smaller cars less, and maybe make them electric.

Not driving is an effective way of reducing GHG emissions from driving, but right this moment, many commutes are impractically long, shortening those commutes takes time and money, useful transit doesn’t reach all people, and there’s no replacement ready for those disabled people who get around in cars now (there should be, but we haven’t gotten around to designing it, so instead, they get cars).  So, given that some of us are really stuck using cars, people need to change how they use them to reduce their impact (and they’ll need to keep doing this for decades, until their car is electric and the electrical grid is mostly fossil-fuel-free):

  • Reduce car trips.
    • car pool.  People did this in the past, people still do it today to help take advantage of HOV lanes.  There are places, now, where people do “casual carpooling” (aka “slugging”) for this.  The win is larger for longer trips because it’s easier to amortize the time to gather passengers, and long trips account for many miles.  This seems like something where an “app” should help; not one done for profit by windfall-seeking tech, but by (contracted by) a transit system.
    • use (grocery) delivery services, carefully.  Don’t use one that just replaces point-to-point car trips with someone else’s, and don’t replace a single trip per week with many smaller ones.  Do use those that bundle several deliveries into a single trip, or do use those that don’t use a car (especially, not a hydrocarbon-fueled car).
    • combine trips (e.g., buy groceries on the way home from work).  Maybe you think you’re already doing this, but if we can do more, we should.
    • don’t drive the short trips; people may not be car-free, but perhaps they can find an alternative for the trips that are short.
  • Shorten car trips.
    • live closer to work.  This is hard, partly because we have social (tax) policies designed to encourage home purchase instead of home rental, and that makes it harder to move.  This is also hard because typical zoning restricts density, which limits the amount of housing that is actually near work. But if the need or opportunity to move appears, favor a shorter commute — 20 miles is 33% less than 30 miles, that’s a savings.
    • use zoning to cluster “work” locations closer to where people already live rather than out in the boonies, so that transit and carpooling are more likely to be effective, and also so that a change in jobs is less likely to result in a huge change in commute.
  • Don’t drive fast.  For energy conservation purposes, this is more about highway speeds, though there are also important safety reasons for not driving “fast” around pedestrians.
  • Use electric cars.  Even with our still-plenty-of-fossil-fuel electrical supply, electric cars are more efficient, overall this is still a win.  But at our current rate of not-e-car replacement, this will take decades.  Nonetheless, for a long commute, try to buy an electric car sooner, not later.  Yes they are expensive.
  • Use smaller cars.  For gasoline-powered cars, obviously, smaller cars get better mileage, better mileage means reduced emissions.  But if it is an electric car, smaller cars have smaller motors and smaller batteries; actually scaling up the electric car fleet will bump into various production constraints (Lithium? Copper?), and the smaller electric cars are, the more we can build before those limits hit.  Note that these are rate-of-production constraints, not resource limits; in the same way that we can only move so many people into a city per year, we can only grow production so fast.  When we hit (temporary) limits, we’ll get price spikes, better to stretch our production capacity into the largest number of cars instead of into the largest cars.
  • Politically, stop inconveniencing other modes.  For example, stop defending street parking from replacement with bike lanes or bus lanes, and stop opposing street designs that prioritize pedestrians.  Don’t oppose camera enforcement of speed limits near schools or in urban areas.  All the other modes must become nicer and safer if we expect people to use those instead of driving; the alternatives to carrots for other modes, is sticks for driving.

These are things to do, permanently, until the electrical supply is green enough and all the cars and trucks are electric.  And yes, this will involve some tradeoffs, some of them unpleasant, but for cars and trucks, our progress in reducing GHG emissions thus far is terrible.  We’ve made a bunch of dumb choices in the recent decades, those choices will cost us now.  We embiggened our cars and trucks unnecessarily, we made rules against building housing close to where many people work.  We decided that the highest use of a good fraction of our urban streets was car storage.  These were mistakes, and now we have to reverse them as fast as we practically can.

And yes, I really think we have to do all this stuff, and quickly.  Not just “we have a schedule” or “we’re waiting on proposals from a task force”.  Do them.  Now.  Sooner really is better.  If it requires new laws, pass the laws.

I have no idea if my comments are any good or actually help, but I figured I would try.  I hope, a little, to get a toe-hold in their allegedly metrics-driven brains.


I read all the comments from Toole Design (FHWA-2020-0001-0853, tracking number kn4-yvok-yobh), and agree with them entirely.

A few that I thought were especially on point included:

Placement of crossing signals; these must be accessible from a wheelchair even after typical snow plowing. See attached picture for a bad example (this is a button-requested-signaled-crosswalk across Fresh Pond Parkway in Cambridge, MA). For that particular button, it is also quite close to a road full of sometimes-fast traffic, which can be nervous-making to drivers if a cyclist approaches quickly, and nervous-making to parents with children who wish to cross.

IMG 20190121 182309

Counterflow bicycle lanes; I agree entirely, these should not be unnecessarily restricted. There are some that I use every day on low-traffic roads that are not parking protected, and they are completely fine. If it were up to me, every single road that was “one-way” for the purpose of thwarting cut-through automobile traffic would be two-way for bicycles because of their reduced noise, pollution, and danger to other road users.

I agree with their remarks about way-finding signs. Times are appropriate; in particular, fast riders not only know that they are fast riders, they know how much faster than usual they are, and can deal with estimates for the “average” or “median” bicycling time. (I default to 15% faster than the Google Maps bicycle estimates; this is a thing I know. I can shave off another 15% if I try very hard.)

In urban areas (my commute crosses Cambridge, MA, errands often take me into Somerville) the 85th percentile rule is completely inappropriate. The most basic flaw is that it assumes that which does not exist, “free flowing traffic”. Actual rush hour traffic speeds are roughly the same as the median bicycle speed, or slower.

Furthermore, in the previous year (2020), we conducted a natural experiment on all types of roads to see what would happen to crash rates when we remove cars from the road, allowing traffic to flow more freely at the speeds more often chosen by drivers. The outcome was not favorable; in Massachusetts, the number of fatalities did not fall in proportion to the reduction in traffic (see https://www.bostonglobe.com/2021/02/08/metro/driving-decreased-mass-last-year-not-traffic-deaths/ ). This strongly suggests that prioritizing driver speed will reduce safety, and that the “free flowing” part of the 85th percentile rule is especially suspect.

Regarding urban areas again, whenever there is any consideration for “traffic flow”, it must include all road users (pedestrians, cyclists, drivers, scooters, skateboarders — I see all of these in Cambridge) and mass transit users must be weighted individually; i.e., it is not “one bus” but rather “50 passengers”. This is a bare minimum; there are issues of equity and access that I am not really qualified to comment on but I know they exist. There are roads in Cambridge where the bus traffic at rush hour, counting people, exceeds the car traffic (Mt. Auburn Street). This was used to justify a restricted lane for buses, which improved bus speeds and (I heard, and it would be expected for improved bus service) led to an even larger number of people using the bus. There are intersections (Inman Square) where the summer rush hour bicycle traffic is 30+% of the total (this was estimated by counting cars and counting bicycles; for a 45-second green, that’s about 22 cars, and 11 bikes means 33%; this is relatively common at summer rush, and I’ve seen as many as 20 — and it’s not that welcoming an intersection.) Winter traffic is lower, but this is a case where lack of safety (inadequate separation from traffic; lanes narrowed by snow piles) causes a mode shift; walking or waiting at a bus stop are both actually colder than riding a bicycle (source; my daily bicycle commute, and getting uncomfortably chilled walking to lunch when I forget to bring a jacket for walking. I have been doing this for years, and have had the experience multiple times.)

Comments on proposed rule on Automated Driving Safety,

When evaluating safety of automated-driving-vehicles (ADVs), be sure to
weight miles driven by where they are driven and the exposure to
pedestrians, cyclists, and other vulnerable road users (VRUs).

Particulate pollution and noise both damage the health of people near
roads, and to the extent that ADVs can be designed to reduce these
emissions, they should. This might be accomplished through better
management of speed, braking, and cornering, and also simple reduction
in vehicle size.

ADVs will be able to pass other ADVs with smaller clearances than human
drivers need, and because of this, could more regularly leave more space
when passing pedestrians, cyclists, other VRUs. People can stumble or
swerve; any resulting crash would not be directly caused by an ADV, but
an ADV could take steps to avoid or mitigate it. Eventually, ADVs can
allow narrowing of lanes in general. This will free up more room for
pedestrians and cyclists, making them more comfortable and reducing
their conflicts (bikes on the sidewalk, pedestrians in the bike lane).

ADVs should not use street parking in urban areas; they should instead
drop-off and pick-up their passengers at loading zones, and then proceed
to off-street parking. This maximizes convenience for their users, and
allows street space to be reclaimed for other purposes.

ADVs can provide is improved road comfort for cyclists and pedestrians.
Two examples are better crosswalk interactions with pedestrians and
better approach to red lights around cyclists. For crosswalks, the
best-for-pedestrian behavior is to make it clear to a pedestrian, as
soon as it is seen that they wish to cross, that you understand, and
will certainly yield to them. A driver might slow down significantly
well before the crosswalk and flash headlights (on a bicycle, it works
to call out “I see you” and wave/nod). When approaching a red light,
human drivers sometimes drive at full speed to the end of a line of
cars, passing cyclists along the way who later reach and pass the
driver. ADVs can be designed to avoid such no-time-saved passing;
reduced acceleration and braking will also reduce noise and energy use.

Any automatically driven truck should include sensors at all of the
usual truck blind spots, and such trucks should moderate speed whenever
there is a risk of a pedestrian movement (e.g. a stumble) that might
cause an overrun.

NHTSA should work to defuse the vehicle-size “safety” arms race.  ADVs
provide a means for doing this with the promise of an order of magnitude
reduction in crashes (if that’s not possible, I’m not sure why we are so
excited about ADVs), but probably not until their adoption is
widespread. Till then, any ADV owner will likely worry about sharing the
road with fallible human drivers and upsize accordingly. NHTSA could
address this earlier with independent regulations on vehicle size;
larger vehicles reduce safety for other road users, so this is
absolutely within any mission to increase road safety.  Or perhaps,
require anti-collision radar on all vehicles above a certain weight (for
example, 3000lbs), to help provide assurance that a vehicle good at
avoiding its own crashes is less likely to be hit by a larger
human-piloted vehicle.  This will also help mitigate problems caused
during ADV adoption, where ADVs will respond to hazards much more
quickly than the humans around them (in particular, behind them);
putting more vehicles on the road now with anti-collision radar would
reduce this future problem.

I would hope that I do not need to provide references to support claims
that particulate and noise pollution are bad for health, but just in case:
(particulate pollution)
(noise pollution)

For “better practices” around pedestrians and cyclists, I have video,
collected on my daily commute through Cambridge, MA.
(signaling to pedestrians in crosswalks)

(passing cyclists unnecessarily)

This last example is quite long, but demonstrates that if ADVs had wider
knowledge of traffic jams and red lights, they could make more use of
safer, quieter, and energy-saving use of no-more-speed-than-necessary to
make it to reach their goal. This driver was notably aggressive, yet
saved no time at all.


Dear Mr. Matt Genova,

I support the Belmont Community Path and request that the Boston Region Metropolitan Planning Organization provide Transportation Improvement Program funding for the project as soon as possible.

This path should be funded for many reasons, among them:

It provides a safe, shorter route for kids from many parts of Belmont to reach the new combined middle-high school; in years past many students took an unsafe shortcut across the commuter rail tracks. The tunnel under the tracks will eliminate the unsafe shortcuts, and the path through town bypasses several busy roads and intersections. Not only will this be safer, it will also provide an alternative to driving to the high school, which causes traffic backups every morning.

For commuters to and from Alewife station, and between Belmont, Cambridge, and Somerville, it adds to the existing local network of bicycle trails and provides a safe and comfortable route that allows people to bypass area traffic instead of adding to it. People working in Belmont Center will have another option for getting to work; people who live in Belmont and commute into Cambridge/Somerville/Boston will have another option for their commute.

For recreation, right now, it will give Belmont residents a better option for reaching the Minuteman Bikeway and the community path in Cambridge and Somerville. Eventually it will connect to Waltham and beyond, and will provide that option for people in Cambridge and Somerville.

Around rush hour, Belmont can be completely stuffed full of cars, making short trips across town (in a car) impractical. Getting to/from Alewife can be particularly difficult at those times. This path provides a comfortable, practical alternative for many of these trips.

I will enjoy riding on this path and it will save me a little time and make my life a little better, but this path is really for other people who aren’t biking much now because they don’t feel safe. I already bike to work in Kendall Square every day; when I started biking to work, my health, in all measurable ways, got noticeably better, and the one-year hiatus imposed by Covid and work-from-home has made it clear, again measurable at an annual physical, what I lose when I don’t bike to work. Friends and colleagues, who themselves worry about health, parking, climate change, whatever, ask me questions about routes and bikes, and the one problem that crops up again and again is not feeling safe on the road, not wanting to be honked at, etc. This path would solve that problem for a lot of people in Belmont, and for people nearby who travel into or through Belmont. They’d save time, money, and end up healthier too. Even people who still drive in Belmont would benefit, because each person who travels through Belmont not-in-a-car, whether they walk, skate, scoot, or bike, makes traffic slightly better, and doesn’t take up a parking space, either.

I should add, some of the backyard abutters along Channing Road have objected to this path because they think it will promote crime. I don’t know their logic, but I’ve certainly heard their worry at many public meetings. However, I’ve been biking on the Fitchburg Cutoff to Alewife since it was just a muddy path through the woods, and back then it was substantially creepier and sketchier than it is today with a well-designed multi-use path. Kids used to gather there to drink and spray graffiti, my kids tell me that it was one of the places to go for drug deals, and I didn’t feel super comfortable there after dark. Now, with a path there, it feels safe. No more drinking. No more weird trash campfires. No more suspicion that I just rode my bike through a drug deal. Instead, I see lots of families walking to and from Alewife and beyond, some biking, and quite a few people walking to or from Alewife after dark. It feels safe because people use it, and people use it because it feels safe.

Masks, again

January 18, 2021

I assume that until this bug is over, it’s not over, and until then I will wear a mask around other people, and I would like it to be a good one. I keep reading papers. I’ve learned that an earlier paper about the goodness of high-thread-per-inch cotton had a flaw, where they failed to neutralize the charge on their test particles, which made it (very) easy for a mask to trap the particles and this overstated the effectiveness of tight cotton weaves. More recently, I read about the performance of mask materials over time, and that was depressing; if you use an medical N-95 mask very much at all, it probably loses a lot of its ability to filter small particles because the electrostatic charges on the fibers go away. Medical wrap (Halyard H600) has the same problem. This is especially true with alcohol, which is a polar solvent that can conduct electricity.

Mask material reuse

What this chart says is that for the best protection, you want a new N-95 mask; nothing else is better, and the different between 99% percent efficiency and 98% percent efficiency is twice as many particles, so a real N-95 really is much better. If, however, the mask is worn more than once, especially if it is exposed to alcohol in small amounts (for example, from hand cleaner) then it might not work nearly as well. For a mask that I’m going to wear more than once, “EX101” looks interesting; it turns out to be a high-grade air filtration media used to make air filters for diesel engines. It does, however, resist breathing more than other materials.

Two other things matter, a lot, in a mask. One is how much it resists your attempts to breathe through it, and the other is how well it is sealed to your face. Once you get to 99%-of-particles-filtered efficiency, small gaps can reduce the relative performance of the mask by a lot. In masks I’ve made in the past with high-thread-count cotton, if they get damp from sweat or condensate, they fail in both ways; their resistance to breathing goes way up, and when you exhale, the elastic cannot keep them sealed to your face and you blow unfiltered air out the sides (you can feel it, it is very annoying). On the plus side, this is a validation that the mask design I use can seal tight. I’m a little nervous about masks that only hook on ears; I’ve worn some of them, and they don’t feel like they’re sealing that well, and shopping, a few times I have seen people wearing such masks where from the side I could see between the mask and their face, all the way to their lips and nose.

Another problem with mask made of materials that resist breathing is that they can collapse onto your face, which reduces their surface area and makes inhaling even harder. It also feels disgusting if you’ve been wearing the mask for a while and there’s some amount of condensate in/on it. However, I figured out how to modify an existing design to let me prop it off my face with coffee sticks, and I’ve since improved it; the coffee sticks are inside now, which looks better and is a little simpler to sew, and more of the seams are on the inside, not the outside

So, this is how I got to where I am now, making masks from two less-filtering fabrics surrounding an inner layer made from EX101, and washing them with alcohol as necessary. I wear those masks whenever I go indoors, and for short/slow bicycle rides. For long or fast bicycle riding, the breathing resistance is too high, so I either don’t do that, or wear a mask that is less good (but I am outdoors, moving quickly, and staying away from other people by default).

Here’s the pattern and the instructions, 2 pages, print single-sided, the first page on card stock if you can, and a series of photos from me making a mask using these instructions. Cummins filtration sells 50 packs of EX101 filtration media (it’s about $45). There’s other mask information at the University of Minnesota, where they have other designs that use this filtration media.

And to the obvious question, why am I doing this, why am I not buying a mask instead? Two reasons. First, any N-95 mask that I know is trustworthy and good, I am probably taking out of the hands of someone who needs it. You might say, “but I see a lot of those for sale, I don’t think there’s a shortage”, but that may just mean that we have different levels of trust. Second problem is, how much do you trust the people selling you the mask? Anyone can claim anything, I look for signs that they are or are not thinking about what a mask is supposed to do. When I look at the masks that are for sale, if I see one with ear loops — I don’t really trust it, because an N-95 that isn’t sealing, isn’t really N-95. Or I see a mask (STILL!) with an exhale valve on it, which means that they’ve completely lost the plot with respect to stopping this epidemic. Or I see a mask that claims to have an insertable filter, but it just looks like a cloth pocket, and really, is that going to seal to my face? There’s no regulations about what is sold to the general public, there’s standards, but is anyone checking claims? We’re very much in the land of caveat-emptor capitalism, and right now the way I caveat, is I read papers, buy supplies from trustworthy sources, make my own masks. (Do I trust Cummins Filtration? Pretty much, especially given the independent research into their filter media. It makes plenty of sense that an engine air filter would work for a long long time.) This is a market failure, government could help, but for a little while longer, our government is crap.

Anyone that knows me, if they sew, if they want some of the filter media, I currently have more than I need, ping me. Either research one of the U Minn mask designs (there’s a weird open-source license they want you to do, it’s odd, but harmless, just takes a few steps) or I’d recommend mine. No guarantees, of course, only I did my best in the time available to do it, my evaluation is it fits my face, I can tell when it leaks, it doesn’t collapse when I inhale, I can get enough air through for moderate physical activity. If I could figure out how to give it more non-collapsible surface area without adding too much to the volume, I would, but this works well enough.

Here’s a newly-made mask using the design above, showing the two props, the interior seams, and the loops for attaching laces/elastic:

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I’ve done a few experiments along the way. Here’s a picture (below) of one such experiment; it’s a mask that I use for longer/harder biking, that has no filter and so outdoors only, stay away from other people. I had just finished biking a few miles outdoors in mid-30F weather, so there’s a lot of condensation (much below freezing, long term, expect ice — that’s what ends up in my facial hair in a normal winter. Facial hair, bad for a mask seal). Experimentally I tried to use more props, on the theory that (1) aligning them with the elastic/cord attachments would be “better” and (2) two props per side would do a better job of keeping the mask from collapsing. I decided against this; I didn’t particularly notice “better”, and the prop higher on my face can actually be a little irritating because it rides directly on top off my cheekbones and is still a little hard through the fabric. This photo also shows how much condensate ends up in a mask doing physical activity in a cold outdoors. I’m not too surprised by the wet/dry condensate patterns, except that there’s more than I expected down near the bottom where it catches my chin.

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This came up at work, where we’re all still WFH and probably will be all through the winter, that Seasonal Affective Disorder is a real thing and likely to bite harder than usual this winter, what with so many people almost entirely at home.

One approach to this is to get fancy lamps and that’s probably not a bad idea, but another, and also this dovetails with how to socialize safely given COVID, is to spend time outdoors. But it’s going to be cold, winter is that way. How do we do this comfortably?

As it happens, I have been riding my bicycle 6 miles to and then from work year-round, near Boston, since early 2015 (and 2+ days every week before that, since 2006, 10 miles one-way). I have some experience staying warm, though it is biased a bit by physical activity and my inherent toaster-ness. However, I know how to round up and have also been out on a bike in single digits, and my advice involves buying stuff from a guy who lets you dial up the warm to levels that have me covered in sweat. Seriously, I have a hat, it has never, ever, failed to make my head sweaty. I call it the dammit hat, as in “dammit, my head and ears will be warm”.

And obviously, tons of people know how to cope already (lots of people work outdoors in the winter, after all), but tons of people are also aghast that I bike in the winter and wonder that I am not frozen when I do. I can only guess that they don’t spend much time outdoors in the winter.  The point is not to endure the cold, but to be warm enough that you don’t care.

“The guy” is Lou Binik, who has a business called FoxWear. He/his minions sew stretchy technical fabrics into things. The ordering process is distinctly old-school, I have always exchanged a few e-mails, the result is at minimum semi-custom for things like tights. I typically pay by USPS-mailing a paper check.

For me, the three best things he makes are (1) tights (2) hats and balaclavas and (3) socks/oversocks. My default fabric choice is stretch polar fleece, he calls it “Power Stretch”, you get your choice of colors and thicknesses. 2.5mm is the thickness of the dammit hat; if you’re willing to settle for black (it is always in style) you can get 3mm. I’ve never tried “double sided fleece” or “Retro-X” but those are even warmer options.

The tights just work, and they’re easy to take care of, just throw them in the washer and then throw them in the dryer (I do tend to use the low heat level in general, to reduce the risk of accidents). They work as an underlayer, too.

For tights-ish pants that are somewhat less stretchy, but more wind, water, and snow repellent, choose “Power Shield” or perhaps “Wind Pro” instead. You’ll need to be sure that it’s not undersized in waist/butt/thighs, because it’s less forgiving there and you may end up feeling like a sausage if they’re undersized. One pair I eventually decided was too tight (my thighs got bigger from the new commute), I gifted them to someone with skinnier legs (For reference, my thighs are 65cm at their largest, so if you’re in that ballpark and ordering pants in this fabric, you might want to mention it). Wearing these, you can go out and shovel snow or run a snow thrower or whatever for a few hours, stomp your feet before you come indoors, and all the snow falls off, your legs are still warm, dry, and comfy.

The socks are a peculiar compromise; they’re not as stretchy and comfy as nicely knit socks, and there’s a seam down the bottom. But, they are super durable, warm, perform well even when (very) wet, and their durability extends to washing and drying; these are fire-and-forget.

Oversocks are a weird thing — super-oversized socks, you pull them on over your shoes. They are unusually helpful for keeping your feet warm, I do not know why. If you actually go for this, you may want to treat the bottom with Plasti-Dip — for that you put a shoe in a thin bag, put the sock on the shoe, find a pan/tray you don’t care about, and then “dip” the bottom of the sock in the Plastic-Dip (more detailed instructions and pictures).

Get the hats with earflaps. Ears get cold, right? If you’re up for a balaclava, you should get one, a stretch polar fleece balaclava is great. Know what your hat size is when you order, that matters.

Another thing to consider is a jacket. I ordered one once, and for me, it’s actually too warm, I almost never wear it biking and instead my son uses it. It’s light on pockets, but warm, comfy, and not incredibly bulky. Looking at the site just now, I see a Snowboard Jacket, and that looks really warm, and it has pockets.

So, my plan for cold winter days when I want/need to just hang around outside, is to wear a pair of thicker tights, the dammit hat, the boots I already own with a couple of pairs of socks (no overstocks), a scarf, and perhaps order myself a Snowboard jacket, with additional wool layers underneath as necessary. If that’s not enough, I have a yellow Land’s End stadium parka to toss over the whole mess that I’ve owned since forever. Gloves, I have some ski gloves for biking, those work. I’ve done this before on Boy Scout skiing trips to Northern Vermont, the goal is not just to survive the cold, but to be comfortable, even just standing around in it.