I’ve been collecting videos on my bike for years now, enough that I can collect them into collections with various themes.  Lately I started poking around NextDoor, which I can best describe as “the social network for old people who like to confirm all the stereotypes about old people”, and I’ve started to use the videos to illustrate points.  Not sure if anyone clicks through or not.

Here’s a reply in response to someone complaining about cyclists “swerving around” pedestrians:

“Swerving around” is an other way of saying “carefully not running into”. People on bikes often get routed into areas where they share space with pedestrians (Cambridge Common, Minuteman Bikeway, Harvard Plaza, other paths) and what we do there is nothing but swerving around, again and again.

Here’s an example; notice the speed adjustment to time passes, and how I choose the “far” sidewalk to get to the crosswalk because it has less foot traffic on it:

Now imagine trying to do all these things in a car — it would be completely impossible, the car is too wide, cannot make the turns, darn-sure cannot fit on the 2-foot wide scrap of sidewalk between lamppost and curb. The lamp-post pass points out another thing, which is that someone who’s been biking on Boston-area streets for a while has a lot more tolerance for tight clearances than the “average” person, and what seems perfectly safe to them will seem much less safe for the average person — that is, I need to make a conscious effort to pass wide (it’s becoming a habit). What’s a little weird is that it depends on whether you’re on the bike or not; I was walking across an intersection, and someone on a bike (oncoming) passed me, and it felt notably close to me (you can see me moving out of her path several times, little handlebar nudges, and she just keeps consuming the extra space. I knew exactly what she was doing, but it still felt “bad”):

Example close passes, where my handlebar is passing above the flex bollards and I am brushing them with my thigh as I ride past. Yes, experienced riders can really do this, I am not kidding or exaggerating:

Here’s another video, helmet camera, notice always moving away from pedestrians, especially children and dogs, plus the bonus jerk-on-a-scooter at the end:

The point here is that it is not about “swerving”, and not about whether someone decided to put a red light over the mess of bikes and pedestrians; what actually matters (for not-cars) is speed control, and clearance. Changing the situation from a park to an intersection does not magically make the bicycle more dangerous; the intersection is dangerous because it ALSO has cars in it.

Just spent 3+ weeks in Europe (spouse had work, I was along as a vacationing assistant more or less), we visited Paris, Madrid, Copenhagen, and spent part of a day in Malmo. Is it perhaps necessary to point out that Cambridge is a wealthy city in a wealthy state in an actually-wealthy nation (that fails to tax its richest people adequately and overspends on war preparation, thus the government is perpetually complaining about “can’t afford?”).

  • I assume all y’all are jealous of this fun vacation (I had a great time). Would it perhaps be nice to live in an interesting place like these?
  • All these cities are, shall we say, unfriendly to cars and especially to parking. Yet Paris actually has quite a few cars in it, despite all the press that Mayor Hidalgo has received. Copenhagen, had cars in it, spouse had to do a day in Aarhus and car-pooled there, the car arrived at the door of where we were staying (a half-block from a no-cars pedestrianized area). Copenhagen, I saw plenty of people older than me, including women, including in the drippy rain, biking. Their raincoat game is strong there.
  • All these poorer-places have great mass transit and some amount of bicycle and pedestrian infrastructure, the lack of which we always trot out as our reason for not making it harder to drive/park. (The Paris Metro on strike works better than the red line currently does.)
  • No doubt someone will point that Massachusetts is not Denmark, we don’t have the density that they do. This is correct, Massachusetts has less area than Denmark (10565 vs 16580, square miles) , more people (7 million vs 6 million) , and is actually denser (900 vs 360, per square mile). “Gross State Product” of MA is $584B (2020), versus either $411B (2022, Purchasing Power Parity) or $387B (2022, nominal). Whatever works in Denmark because of their population density and wealth, should work better in Massachusetts.

So, we could add bike lanes and fix mass transit, if we wanted. That’s a choice we make, we have the money, we have the density. We cannot do “cars-cars-cars” in Cambridge/Somerville/Boston/etc without noise, pollution, traffic jams, and a low but not-zero level of pedestrian crash deaths; that’s not a choice, that is physics. And the way to get better transit is to quit voting for lower-my-taxes penny-pinching conservatives; if you complain about the T and then vote for the guy (and the party of the guy) who broke it, you’ll get to complain some more in the future.

Slide show from the trip (Google Photos).


One of those “you cannot unsee it” things, for me at least, has been the way that partly damaged roads become badly damaged roads whenever it rains and cars continue to drive on them, especially at speed.  The cracks and potholes fill with water, and if cars and trucks go through them rapidly, the tire jets water out of the pothole, and that water jet helps erode the pothole, quickly.

The discussion I find about this searching the internet seems to talk less about cars and this splashy dynamic wear, and more about how water in a pothole seeps into the road bed, weakening it and leading to subsequent accelerated road wear.  Finite elements modeling of pothole water jets seems like a fun project for someone who knows how to do that sort of thing, it would be nice to know how that wear depends on car speed (if it depends on car speed).

Concord Ave in Belmont uphill from Cambridge line, showing several potholes filled with water and old patched potholes, together with debris sprayed out of the potholes including small rocks.

The spraying action is much more obvious on the separate, raised cycle track a little further down the road, where the debris spray patterns are more preserved:

PXL 20230302 143019089

I’m not sure what’s the best way to handle this.  I ride a bike most days, even the rainy ones, so I’m usually not making the problem worse.  More aggressive crack sealing (look further out in the lane in that photo, there is a long crack in the road that will not get better) and pothole maintenance would probably help, but those things cost money, and “someone” votes against gas tax increases (and the gas tax is currently too low, road repairs are subsidized from other funds).  Another possibility, when the potholes are concentrated in one lane, would be to block off the lane on wet days.  Long term, for patterns like this, it might make sense to use a thicker layer of tarmac or a firmer roadbed to reduce wear (in the adjacent-to-cycletrack case, the water table is not far below the road, and there’s also a reasonable amount of heavier truck and bus traffic).

This stretch of Concord Avenue has been susceptible to potholes as long as I can remember.  Before it was repaved to add the cycle track, I remember treating it as a no-go zone for bikes, because it was both multilane AND throughly potholed along the edge, meaning a substantial risk of swerving into traffic either to avoid a pothole or because of hitting a pothole.

About my bicycle(s)

February 11, 2023

There are more bikes like mine on the road nowadays, also more e-bikes on the road, I get more questions than I used to, which is nice actually, it is so heartening to see more people figuring out that they don’t need cars for every last trip.

But, the questions, the answers, I am bad at that, I excel at digressing and probably making people sorry they asked, so instead I thought I should write them all down, hopefully in a short and coherent form, then stick a QR code on the back “if you have questions about this bike….”

So, answers, to the questions:

This is a “long tail” cargo bike either designed by or based on a design by a company in California called XtraCycle.  I’ve been commuting on bikes like this a few times a week since 2006 (10 mile commute), every day since 2015 (6 mile commute), year round including winter and snow.  If the bike is green (Surly Big Dummy), the frame comes like this, but I customized the parts, if the bike is pink (XtraCycle EdgeRunner 11i), this is relatively close to as-sold.  You can buy a bike pretty much like this, if you want.  You can buy a bike like this with an e-assist, if you want.  They’re not cheap compared to “normal” bike, but they are cheap compared to a car, and in 2022 I drove and biked equal distances, and that includes a car trip from Florida to Massachusetts.

I buy most of the groceries riding this bike.  I have carried children and adults on the back; the official load limit is 200lbs, I have carried 250 and it was okay, though a lot of work.

This bike does not have an e-assist.  A day may come when I need e-assist, but it is not this day.  I can ride up most hills with most loads if I have to, but if there’s a way to avoid the hill, I just might take it.

The bike handles, very, very well.  I ride it no-hands often, including carrying loads of at least 100lbs.  I’ve also borrowed a friend’s very expensive road bike (Tom Kellogg Ti Spectrum) and according to my butt, the unloaded no-hands feel is exactly the same.

For the winter, I put a studded snow tire (Schwalbe Marathon Winter) on the front, and use a “snow tread” tire (Continental Top Contact Winter II Premium) on the rear year round (it has super traction in the summer and no particular increase in rolling friction or lack of durability, and I am lazy about swapping tires).  I wear regular shoes or boots, making about the same choices I would if walking, add bar mitts to protect my hands, and otherwise tend to underdress for the cold, but with a wind blocking jacket.  I wear a thin stretch polar fleece cap under my helmet.  Biking makes heat; I am big, the bike is big, I make a lot of heat.  Adjust your clothing to match your heat output, don’t be surprised if you warm up after the first mile (after years of experience, I plan for a “brisk” first mile, otherwise I have to take the clothes off anyway and I will have to take off more around mile four.  Dinking around my neighborhood, I dress plenty-warm because I won’t ride enough to warm up).

The worst weather is cold rain, the next worst weather is high heat + humidity.  If you’re biking to work, on those days a change of clothes is a good thing (I have a drawer by my desk, it has spare clothes in it, I very rarely use them).  But bad weather is rarer than people think (literally, I ride to work every day.  I should know.)

I am neither young nor slender; my main advantage is that I biked a lot when I was much younger and got pretty good at it, and in my 40s, when my annual physical started to be less fun, I realized that I needed more exercise, and that “old” people could ride bikes.  It didn’t hurt that we were busy fighting an immoral war over oil and had reelected the guy who started it; this seemed like a minor protest to me, I could send slightly less money to the oil companies.  The first month commuting was work, then I started to get stronger, as one does.  The first winter commuting I was somewhat randomly prepared and spent too much money on stuff I didn’t need.  At this point I have a tremendous advantage over someone starting “fresh”, because 16+ years and 40,000+ miles of biking in traffic in this area means that I’ve learned a little bit and acquired a bit of physical conditioning.  So, if you’re thinking about it, don’t wait, it won’t get any easier.

This bike does not have drop handlebars; it does not have mountain bike flat handlebars.  Those choices are intentional and for daily commuting and erranding use, you want these handlebars (52cm Nitto Bosco).  Yes they are skinny, yes they increase my air resistance, but I sit taller, can see, can be seen, am much more comfortable.  Flat bars and/or the leaned over posture can give you numb hands and fingers, for various reasons, it happens to lots of people, including me.

Yes the saddle is hard as a rock, that’s what works for me.  Well-padded saddles don’t work for me, I’ve tried them.  Your butt is not my butt, you might have a different preference.  I think the Brooks B17/Flyer is actually a good first bet for most men, on account of their history, popularity, and habitual use by men (but the Brooks Cambium is a very hard saddle, be careful of that.  Also, I tried one, and broke it).  “Terry” is another good choice, especially (as I understand it) for women.

I tend to wear a helmet riding in traffic, or in terrible conditions.  Off-road paths or in a low-traffic neighborhood, I don’t think it’s necessary.  I do however use lights that are powered by my front wheel and they have no off switch; if the bike is rolling, then they are on.  There’s research that shows that this prevents with-car crashes about as well as helmets protect your head in the event of a crash, and makes the need to dress “for visibility” somewhat irrelevant; the bike takes care of visibility for me.

Everyone vaguely able to should bike more; there are cargo bikes, e-bikes, e-cargo-bikes, trikes, e-cargo-trikes, you name it, you can get a bike that will do the job for a lot of the trips that you might drive today.  The exercise is really good for you if you can make it part of your routine, and at least in the Cambridge/Somerville area, it will cost you not much time, because driving here isn’t that fast.  Cars are bad for their drivers (lack of exercise), bad for other people (noise, pollution, crashes), bad for the country (murderous assholes get their money from selling oil, it’s a world market), and bad for the planet (climate change, it is a thing).  And if you think cars are actually a good thing, when was the last time you heard someone saying “what our neighborhood needs, is more cars.  Can we run a highway through here?”

I do most of my own maintenance and repairs.  Bike repair is not as user-friendly a business as car repair, I learned how over the years, so it is more convenient to do my own.  It is not hard, and takes only a few specialized tools (mostly, metric wrenches) that you could mostly stuff in a pair of jean pockets if you needed to (the pockets would however be heavy and lumpy).

Regarding specific equipment choices, in general I optimize for convenience, comfort, and safety:

  • I just use flat pedals, not cleats.  I have used cleats in the past, they caused me to ride less because of inconvenience of different shoes.  I don’t use toe clips either, they mess up your shoes, and delay transitions on/off the bike.  I don’t really need the additional power.  This also makes winter footwear easier to deal with.  Yes, I also own the incredibly expensive Lake Winter Mountain Bilking shoes, it’s nice, but not as sturdy as plain boots.
  • The tires are fat, not skinny, because (good) wide tires have lower rolling resistance which is what matters at most commuting speeds.  Fat tires require less frequent reinflation, are easier to remove/install if you get a flat, protect the rim from potholes, protect ME from potholes, and give a more comfortable ride.
  • I use internally geared hubs on cargo bikes because those allow me to change gears when I am stopped, make it easier to use a chain guard to keep my pants clean, and let me build a stronger rear wheel (freewheels require a “dished” wheel that is not as strong).
  • I have a shock seat post because the roads around here are terrible.  I run it pretty “stiff” because constant bouncing up and down seems to make my knees too tight; what I want is protection from the worst bumps, that might really hurt me (that is, old backs don’t like surprises).
  • I don’t bother to clean my chain, ever.  I do add lubrication, sometimes.  I replace chains about once a year, I am large, the bike is large, I destroy chains.  This sometimes requires replacing other parts of the drive train that get worn by a stretched chain.

If you have other questions, bother me in the comments, I’ll try to answer them.

Layoff shit

January 28, 2023

I survived the layoffs at work, a lot of other people did not.  It occurred to me that I have some unfortunate experience with unplanned loss of job, and should pass on a little bit of what I have learned over the years.  Some of this is dated, some of it is better now, but this is also somewhat about setting expectations and avoiding mistakes.

First, expect it to take at least two months to find a new job.  Maybe three.  It was worse in 2002.  Things might be better in this economy, since we’re not actually in a recession (2022 4Q real growth of 2.9% according to Justin Wolfers on Twitter — not a recession).  You should treat this like a full time job, not just send out a few resumes and wait for the magic to happen, but make lists of places you know, and people you know, and ask those people, etc, and keeping going until you have a written offer that you have accepted.  You may want that second or third offer to help with negotiation, or if the negotiation goes poorly, or maybe you’ll just turn up a better offer late in the game.

If you have friends or former colleagues who were laid off, if you hear about job openings, tell them, pass on probes from recruiters, etc (I may ignore pings from recruiters if I am happy and busy at my job, but I am never, ever rude, you never know, if not for yourself, maybe for a friend).

Some places you interview, even famous respected tech companies, may not acknowledge receipt of your application.  In at least one case they may not let you know that you did or didn’t get the job after an interview (in that case, asshole that I am, I just applied again a few months later and was amused by the confused/embarrassed response from the recruiter, yes, this was 2002, you take your fun where you find it.)

And, isn’t it fucking amazing that you have to pass an interview again?  Like, you cleared the hurdle to work at BigCorp, they had interviews, you worked there for years, maybe, interview for the delta, did you learn anything since the last interview?  But no, write a function to plot the time on a clock, or how would you deal with a difficult co-worker, or design a login system for tiered access to different magazines from the same publisher.

Second, health insurance.  COBRA is the thing that requires your employer to give you the option of paying to continue your group insurance with them.  It’s a law, you can thank Ted Kennedy for it.  HOWEVER: there are deadlines, and they are hard, not “fix it with penalties”, if you miss them, boom, no health insurance.  I hand-delivered checks.

If you/spouse is pregnant and has a child born under COBRA-extended insurance after a job change, it may be the case that the mom’s costs are paid by COBRA but the new child’s insurance is under the new job (a brand new dependent, right?).  This causes paperwork, the hospital will not get this billing right.  Also in this situation, continue the COBRA coverage for mom until the postpartum seal of approval from a doctor.  This may have changed since Obamacare, because insurance companies are no longer allowed to play the pre-existing condition game like before.  But, beware, and beware of conservative political shenanigans (judges etc) that might revert things to a worse state.  Conservative politicians don’t care if their actions kill or bankrupt you, so just be careful (maybe enthusiastically support their better-to-at-least-less-awful competition, so the future will suck less).  To summarize, if you are in this situation, (1) you do have access to insurance if you get the Mother-May-I incantations right and on time (and perhaps pay for it) but (2) get good advice on the details and (3) be a little careful about any single source of advice; ideally former-HR, hospital billing, and insurance will all agree on how things are supposed to work, and (4) do not be late with any bills or paperwork.  Best healthcare in the world, that’s us here in the USA, ain’t it great?

If instead you decide to retire, there are some weird deadlines involving Medicare and change of job.  I don’t know these exactly, but if you get these wrong, the costs are permanent.  Again, get good advice, there’s enough time to do this right if you don’t dilly-dally.

Third, new employers.  If this is your first job, or you’ve never worked for a startup, or only at California companies, here are some things that I learned along the way.

Depending on their size/age/competence, startups may or may not have all benefits, they may or may not offer a competitive salary, a lot of your compensation may be in the form of magic beans which it turns out are usually worthless.  Their funding may get uncertain, for example, if there’s an angel investor involved, the angel may have a cash flow hiccup, or a divorce, or who knows.  If there’s two angels, they may get into a “renegotiation” over investment shares that ends badly for the startup.  Or a bunch of Saudi Arabian “religious” fanatics might decide to fly some planes into buildings and tank the economy.  So, that is startups.  Startups can be fun, it is different as heck from paperwork and process-filled mega-corps. But they might not be stable.  I am still good friends with many of my former startup colleagues, from Centerline (aka Saber), NaturalBridge, Oryxa, and even Thinking Machines.

If you’ve only worked at California companies (e.g., Facebook, Apple, Netflix, Google, Oracle, Intel, Twitter) you have probably not been asked to sign a non-compete agreement.  If you get a job offer from a not-California company, a non-compete may be a condition of the offer.  These are bullshit things that employers in a lot of other states do, they are bullshit because one sure (if not easy) way to get rid of them is to get a job with a California company, especially if you move to California.  They’re also bullshit because the California economy shows that non-compete agreements are not only unnecessary for a healthy, diverse economy, they might even be bad for it; rational business owners who wanted to be more successful would organize to get them banned everywhere, to help replicate the California experience (perhaps business owners as a class are more control freaks than income maximizers, that’s one explanation that fits observations).  Employment lawyers can help, or you can just sign the damn things, knowing that they are likely unenforceable.  These are not always carefully drafted, especially at startups, and startups may have ridiculously grandiose ideas about the scope of their business (“software, all of it”).  There’s intermittent efforts to get rid of these, but for now, they’re a thing.

So, that’s what I’ve learned, or at least what I recall learning.  To anyone in this situation, I am truly truly sorry, I have been there, it really sucks.  Long-term consider supporting unions, consider voting for actual European-style social safety nets, consider voting for actual job protections.  And always have a plan B, if you can manage it.

When I first heard about effective altruism, it was, from a certain point of view, a completely sensible thing; given dollars to donate, how can you make those dollars have the greatest effect?  And, the guy I heard it from, very much walked the talk, he donated an admirably substantial portion of his non-trivial tech-industry compensation to charity.  I might hedge a little on “how sure are you about the numbers guiding your donations?”, but basically super-admirable.  Effective, even.

However, apparently, recently, some weird crazy “longtermist” bullshit has taken hold in EA, and someone got the brilliant idea of claiming that their goal was to save the maximum number of lives in the future, where by future they mean “hypothetical future space civilization of unimaginable size” and/or “a giant AI into which we have uploaded zillions of human minds”.  “Altruism” is helpfully redefined as “whatever maximizes the number and/or welfare of these completely imaginary people”.  I.e., it’s bullshit, intended to let its proponents claim that whatever silly-ass thing they want to do, is “altruism”, and furthermore, that it is the best possible altruism.

So, why is it bullshit?  First, it’s very, very unlikely that we’ll expand out of our solar system, and if somehow we do, we have no idea when that will be possible, because we currently lack the physics and biological knowledge necessary to make it happen.  It takes too much energy, propulsion systems are too energy-hungry, and the time scales far exceed our ability to keep humans alive with no external support.  All these problems need solving first, assuming that they even have solutions.

Second, where would we go?  We haven’t identified any actually-habitable planets anywhere else, yet.  That’s something that we might be able to do in the not-too-distant future, with another turn of the giant space telescope crank, but as yet, zero other planets are ready to support human life out-of-the-box, and we have no guarantee that the habitable planet we do find will be at anything like a feasible distance.  10 light-years is unimaginably far, but what if it is 1000?.  Or, suppose we compromise, and try terraforming?  We haven’t even done that in our own solar system, and the best possible day on Venus or Mars is still more lethal than the worst day anywhere on earth outside of an actual natural disaster.  Anything we could possibly do there, we could more easily do here to fix problems with our own climate.  (A good start might be “stop doing stupid shit, stop other people from doing stupid shit”.  If we can’t even manage that here….)

Third, even if we accept the airy-fairy bullshit that we’ll be able to leave the solar system, find a planet to adapt, change it, and bootstrap a civilization there, then repeat this process exponentially, we have no clue what the timescale for doing this will be.  We haven’t solved any of the problems yet, and we’ve got no particular reason to believe that we’ll solve them in this century or the next.  Implicit in the bullshit longtermist hubris, is the assumption that *we* will be the ones to solve them, and that *we* know the steps towards that solution, so obviously, whatever is good for *us*, is good for those future hypothetical humans.  Or perhaps, we expect an answer from that general-purpose-human-exceeding-AI (that, like self-driving cars, is coming real soon now) that we have already determined will find solutions to these problems, instead of telling us, “actually,  no, you are stuck here on earth.  Period.  Here’s the proof”.  Assuming, of course, that such an AI is even possible, and that some other scaling law doesn’t crap out first.

I would propose that it is more prudent and effective to pay attention to the very high probability event that almost all humans live on Earth, and will continue to do so for hundreds of years, and that we should worry about ensuring that civilization-endangering disasters are avoided here, and that human capital (i.e., health, happiness, longevity, intelligence, education, productivity) is maximized.  We should assume that whatever we do in the distant future, we are stuck here for a long, long time, and if we don’t make plans for that long long time here, there won’t be a future beyond. That would mean taking climate change more seriously than the US currently does, and that would mean looking at obvious inefficiencies (the US, fat and happy, has quite a few of these) and replacing them with better systems.  It would mean taking all the “not-first-world” countries seriously, taking their health, social, political, and economic needs seriously, and not just exploiting them for a quick buck.  We should think about political systems that are resistant to fascist, racist, and nativist impulses, and adopt those systems.

And, in the unlikely event that we do start a galactic civilization, these efforts here would not be wasted.  If we can’t maintain a habitable atmosphere and climate on a favorable planet, it’s hubris to think we’d do it elsewhere, so we’d better start practicing till we get good at it.  The same externalized-cost problems of capitalism that make planet-scale pollution hard to control here, will surely travel with us wherever we go, running away from one’s own intrinsic problems is (ahem) a well-known waste of time.

Postscript: today I discovered that their bullshit extends to climate science.  These guys are truly full of shit.

Disclaimer: I am not completely unaware of the intricacies of voting systems, but there’s a lot that I don’t know.

Once upon a time I was a fan of ranked choice voting, but I’ve decided that for a single-winner election we would be better off switching to a primary+runoff where the primary is done with approval voting, and the runoff (between the top 2 from the primary) in the usual way.  Understand, I am in no way a fan of the first-past-the-post status quo, I merely think that we ought to seriously consider another alternative.

There are three reasons.

First, complex ballots are a problem, and people can screw them up.  A ranked choice ballot is more complex and there are easy ways to get it “wrong” so that you no longer have a valid vote, and then what happens?  There’s also many more bubbles to mark — if 5 candidates, 20 choices, of which only 4 may be marked.  Approval voting, 5 candidates, 5 bubbles, you can (sensibly) mark as many as 4 or as few as 1.  Screwing up one bubble leaves the others still valid, whereas screwing up one bubble on a ranked choice ballot may invalidate the ranking.

Second, the process of tallying up the vote is complicated and difficult to explain.  I’ve seen the explanation, and I agree with how it works, but it is complicated and plenty of people will be confused by it, perhaps not trust it.  Approval voting is easier to explain; each candidate gets the number of people who thought they were “okay”, and the primary will be between “most ok” and “next most ok” from the approval vote.

The combination of these two problems means that sore losers may challenge elections, and it will be difficult to convincingly demonstrate that they are just more losers.  (Of course, Republican sore losers will challenge any result that does not go their way, but with a simpler system, they’ll look more ridiculous). More ballots will be spoiled, and recounts will be tricky and annoying.

Third, approval and 2-way runoff have the property that counting can be split by precinct, and then the sub-results combined.  Ranked choice doesn’t work that way; reasoning about partial results is far harder.

One thing that I think inclines people towards or against ranked-choice is different models of voter motivation.  One advantage of ranked choice is that expressing a secondary preference does not harm your first choice (or so I understand).  If I like Alice then Bob, then Carl, I just express that preference, my 2nd-choice vote for Bob does not harm Alice’s chance.  This is very important to some people.  In contrast, in approval voting, if I “approve” both Alice and Bob, that vote for Bob may reduce Alice’s chances; if voters are focused on a favorite candidate winning (“Alice or bust!”), this may lead them to try to do the sort of strategic voting that we hate in the current First-Past-The-Post system (“I really like Alice, and Bob and Carl are both okay, but I think a lot of other people like Bob so I’ll only vote for Alice, and Carl just in case”).  On the other hand, if your goal is just to get good candidates into the runoff, then you’ll vote for anyone who doesn’t suck.  And if you wish to merely vote against a particular candidate, approval voting makes that easy, just vote for everyone but the bad guy, where ranked choice might require more strategic thought.

There’s another alternative voting system that is more expressive than approval voting and shares some of its good properties, and dodges Arrow’s Impossibility Theorem.  Instead of approving or ranking candidates, voters assign “scores” to candidates, for example, numbers between 0 and 9, subject only to limits on the maximum and minimum scores.  This is called “score” or “range” voting, and its proponents are very enthusiastic.  Tabulating votes can be done in parallel, and it is harder to spoil a ballot, though the ballot is more complex than an approval ballot.  The difficulty, to me, of score voting is that it is hard to reason about what a range of scores means — if I prefer Alice to Bob to Carl, is that 9-8-7 or 9-5-1?  Do I have an easy way to measure my hypothetical satisfaction?  I suspect that it many cases it may devolve to 9/0 approval voting.  One advantage of score voting is that it can be done in a single election; one disadvantage is that it might be vulnerable to accusations of “complexity” or “voter confusion”, though not as much (in my opinion) as ranked choice voting.  Wikipedia calls these “cardinal voting systems”.

Hello all, you are probably unsurprised to hear this from me, but I like the new bike lanes on Concord Avenue. I ride on them at least 6 times a week (5 days to/from work, plus farm share from Farmer Tim on Sunday), and they reduce stress even for someone as accustomed to traffic as I am.

I was also pleasantly surprised at the quality of the pavement; there are a few imperfect spots, but it is not as bad as I had thought it might be, and I would not hesitate to recommend it to other people.

I’ve heard through the grapevine that people now parking closer to traffic feel that is not comfortable to get in and out of their cars, and why yes, I have biked in that same space many, many, many times, I can see how they might feel that way.  That is sort of the whole point of a protected bike lane, reduce exposure to traffic.  Drivers newly exposed to traffic may feel this rather keenly, but it is a constant risk to someone riding on a street on a bicycle.

One reason to have such a bike lane is that it reduces the overall person-minutes of traffic exposure; it is a net win for that problem. Here are some measurements and estimates that I hope demonstrate this.  I timed myself this evening traveling from Baker to Orchard, and it took 2 minutes. I also experimentally got in and out of a car parked in our driveway and walked around it, and I was easily away from the side of the car in 15 seconds either entering or exiting. That is, each person on a bike traveling that stretch of road is exposed to about 4 times as much passing traffic as someone entering or exiting a car (2 minutes versus 15 seconds to enter plus 15 seconds to exit). If I had to guess conservatively, I’d say that (in one direction) there’s at least 15 bikes per hour between 8am and 10am and again between 5pm and 7pm (60 bikes), plus (really guessing) at least 5 bikes per hour between 10am and 5pm (35 bikes), for a total of 95 bikes, for one direction. I base my rush hour estimate on seeing at least one bike moving in each direction almost every time I commute on Concord Avenue, and they are as much as 2 minutes away from me, and I don’t count because I am the observer, so bikes are 4 minutes apart at rush hour, or 15/hour. 95 bikes times 4 is 380 — if fewer than 380 cars park on one side (or the other) in a given day, then the protected bike lanes result in less traffic exposure. I counted parking spots from Baker to Orchard on the north side (which has more spots) and got 57.  380/57 is 6-and-2/3 — unless the average weekday parking traffic per spot is over 6-and-2/3, we’re better off (fewer people-minutes of traffic exposure) with protected bike lanes. I don’t think there’s that much traffic in those spots. I suspect that the average weekday cars per space is closer to 2, so I could be off quite a bit in my estimates and the protected lane would still be a net win.

This is also just raw traffic exposure, ignoring dooring risk, and assumes that someone parking their car gets in or out of their car without waiting for traffic to clear; time is time, they’re exposed for 15 seconds. Actual cautious-driver behavior reduces this risk whenever there’s any gaps in traffic (it’s easier to find a 15 second gap, than a 2-minute gap).  There are caveats and quid-pro-quos, but none of them results in winning arguments against a protected bike lane; for example, in the old configuration, if no cars are parked, then I would often ride through parking spaces (where the protected lane is now) to increase my distance from traffic — but if no cars are parked, people aren’t exposed to traffic parking their cars.  Or, if there is very high turnover per space, yes drivers are more exposed, but then the risk of dooring becomes high enough that it cannot be ignored.

I do sympathize with people who think parking is unpleasant, and that’s one of the reasons I ride a bike instead — I hate parking, too.  I’m not young, I’m not thin, it’s not a short commute, I do this year round, I keep waiting for more other people to realize that they could do the same.  A protected bike lane removes one of the frequent and otherwise intractable objections that many people have to riding a bike around here.

A friend of mine long ago told me that I forget that most people don’t know what I know, and don’t figure things out as quickly.  And even so, it took time for me to figure things out, I know of things that were right in front of my face for decades, and I did not notice them.  So, after over 40,000 commuting and errand miles on cargo bikes since 2006, and as someone who has more than one copy of Bicycling Science, as well as my own personal copy of Food, Energy, and Society, here’s some stuff about bikes that I’ve learned and other people appear to be less clear on.

Stopping power, turning ability, bike geometry

The physics behind the numbers below is discussed, in detail, in Bicycling Science.

A useful thing to know is that rubber on road has a sticking grip force that is about the same as the force against the road, for dry pavement.  That means that a vehicle that is low enough to the ground that it will not flip will have a maximum deceleration before it skids of 1g (g = earth’s gravitational pull), or 32 feet per second-squared (9.8 meters per second-squared, or 22mph per second).  That is, if you are in a car traveling 22mph, the quickest you can possibly stop is one second (your speed decreases by 22mph per second of 1g braking), and in that one second you will travel 16 feet (the formula for distance traveled is x = v0t + 0.5at2), t is 1, a v0 is 32 ft/s, a is -32ft/s2, so 16).

On a “normal” bicycle, two things limit this.  Because the rider is most of the mass and is positioned relatively high, before the front tire exceeds its grip on the pavement, the rider will instead rotate over the front of the bike onto the road.  This occurs at about 1/2 g. A corollary of this is that it’s not a great idea for a cyclist to tailgate a car; if the car stops hard, the cyclist is physically unable to stop as quickly without being flung onto the pavement or the back of the car.  The exceptions to this are bikes where the center of mass is further back; a tandem with two riders, or a box bike, or a long-tail cargo bike that is also well-loaded to the rear.  On the other hand, a penny-farthing or high-wheeler, where the rider is positioned almost on top of the front axle, has very limited ability to brake without flipping.

The other problem is that even on differently designed bicycles where the rider will not flip, because a bicycle rider uses their front wheel for steering, when it goes into a skid it becomes very likely that the bike (and its rider) will fall down.  This is not guaranteed, and with years of experience I have survived such skids once or twice, but the first time I had a front wheel skid I hit the ground so fast I was down and in pain before I realized what had happened; it’s much faster and more violent than a rear wheel skid.

A further problem is that stopping quickly requires a fair amount of arm force to keep you on the bike, and in the worst case you’ll just keep moving while the bike stops underneath you.

Rear-wheel braking is slower yet; because stopping shifts your center of force forward, it reduces the force on the rear wheel, which if it is the braking wheel, will have less road grip.  On a normal bicycle this limits rear wheel braking deceleration to about 0.25g, whether you do it with a caliper brake, coaster brake, or by jamming your legs on a fixie.

In theory (not to be confused with practice), a skilled rider with enough spare room on the road could turn their (normal) bicycle with a full g of centripetal acceleration in the same forward displacement needed to stop it (with 1/2 g of forward deceleration).  (Math: for centripetal acceleration, the radius of the circle is v2/acentripetal; for forward deceleration, the distance to zero velocity is 0.5v2/abraking; however because a normal bicycle can turn twice as hard as it can brake, the circle radius and stopping distance are equal.)  HOWEVER, in practice this would be stupidly risky, because it does not reduce your kinetic energy and if you fail (failure is always an option) the resulting crash will be far more dangerous.  This daring maneuver also requires much more clear road space than simply braking.  And, on a tandem or cargo bike of any sort, the longer bike’s improved braking ability beats its unimproved ability to turn.

Perception and reaction time

Bikes lack stopping power, but for most people on bicycles (upright bicycles, rider not wearing headphones, not seriously impaired hearing) a person on a bike is far more able to perceive what is going on around them.  They are (usually) seated higher, don’t have an additional layer of glass in front of their eyes, or supports for that glass obstructing their view, or bulky hood hiding who knows what, and don’t have the noisy engine or layers of acoustic insulation obscuring sounds around them.  And, because the front of a bicycle is much shorter than almost any car’s hood (excepting front-box cargo bikes) their riders are able to position themselves far forward and look around corners.

Reaction times for bicycle riders seem better (from videos of my own reactions) than the norm assumed for drivers.  I think this is mostly a result of better human factors in the brakes; to stop a car, a driver must lift their food from one pedal, move it over, and depress a different pedal, whereas a cyclist with hand brakes can maintain their fingers over brake levers in traffic, and activate the brakes in a single motion.  I’ve measured real-world on-bicycle reaction times as low as 0.6 second, and some perhaps as low as 0.5 second (which through the camera lens, looks superhuman).  0.9 second, which is about the estimated driver reaction time, is what I get when I am distracted — it looks fine on the video, but at the time it felt like I had made an enormous mistake.  The failure modes for panic stops in cars and bikes also differ; on a bike, there’s a risk of a header from braking too hard, on a car the risk is that your foot will miss the proper pedal and you will accelerate instead.

There’s an additional problem related to cognitive load; if you’re actually evaluating everything within your stopping distance that could go wrong, as your speed increases, that distance increases, and it increases at a greater rate than the speed increase.  A driver traveling 30 miles per hour has 2.5x their stopping distance at 15mph; to understand what’s in front of them, they need to know 2.5x as much “stuff” about their surroundings, and they need to update that knowledge at twice the rate.  The same thing applies to someone on a bicycle, but common case there is 20mph or below, not even 25mph, so this is less of a problem (people biking should be really careful at “high” speeds like 30mph, because we have so little experience at those speeds; my time over the last 16 years traveling 12-20mph is measured in months, my time above 25mph is measured in minutes.)

The combination of better reaction time but lower stopping deceleration means that up to about 20mph, hand-braked bicycles and cars have about the same stopping distance, with bikes slightly ahead at 17mph and slower.  However, because people on bikes have much better perception and less cognitive load, they’re more aware of what’s around them and can make more sense of it.  A corollary of this is that to a driver, a cyclists’ choices may appear “random”, but this is because the cyclist is (often) acting on information that the driver lacks.  Just for example, if I hear a car approaching an intersection from the left, I may stop without ever looking in that direction, even if the right is obviously clear.

There are other not-obvious-to-drivers effects at work.  When stopped at traffic lights, because they take up so little space, cyclists usually are stopped at the front, and over time, can collect a lot of information about signal timings, local road conditions, and local traffic patterns.  This can mean things like “the walk signal comes 3 seconds before the green” or “the light is long to allow pedestrians to cross, the side traffic usually clears after 5 seconds and then it is safe to run the light”.

 Two wheels versus three wheels

People who have problems with balance or coordination can’t necessarily use a bicycle, and can instead use a tricycle.  For lower speeds, the tricycle is more stable because the center of weight sits well within its wheels.  At high speeds, however, tricycles become riskier to turn because most tricycles cannot tilt, and because they cannot tilt, they risk flipping.  This is not universally true; there are tilting tricycles, very-low-to-the-ground recumbent tricycles, and experienced riders can throw their weight around on the tricycle to counteract this effect, but these are not common case.

So, basically, three wheels is more stable at low speeds and easy turns, less stable at higher speeds and with rapid turns.

“Motor” efficiency

Bicycles are efficient for carrying one or two passengers because bicycles have small weight and move relatively slowly (both compared to cars), but viewed as a motor, we humans are only about 25% efficient; 75% of the food that we eat for physical energy, we turn into heat, and the food that we eat took energy to produce. Because humans are such inefficient motors, and modern batteries, motors, and their controls, are quite efficient, it is entirely possible for an e-bike to be the more efficient choice, depending on details:

  • Humans have varying diet; the more carnivorous someone is, the greater the energy cost of their diet (generally, there are further details, but meat tends energetically expensive).  But, contra that, what matters is the marginal calories, not the average calories.  When you exercise more, you may find yourself craving carbs more than usual, not lobster.
  • An e-bike, being easier to ride, will tend to generate more travel and thus consume more energy.  However, if that extra travel would have occurred in a car, then it is still a win.  An e-bike makes it easier to ride more quickly (up to 20 mph in the US), which is somewhat less efficient than riding at typical commuting speeds (12-15mph seems typical without e-assist).  However, if the alternative to a rapid trip by e-bike is a trip in a car, then again, it is still a net win.  Notice how in both cases, the unfavorable comparison is to a bicycle trip that might be purely hypothetical, whereas, if the actual other trip is in a car, the e-bike is far and away the energy-saving choice.

Another under-appreciated corollary of the wastefulness of the human engine is that we get hot and need the airflow that a bicycle provides.  Climbing hills is famously hot because our energy (and heat) output go up, while the speed of the cooling wind goes down.  Stationary bicycles tend to require fans.  And pedal-powered electricity generation gadgets are usually a bad idea; yes we get the exercise, but we also get very hot, will get extra-sweaty, and may require a fan for ventilation, and the fan is not energy-free.

A happy corollary of our wasteful human engines is that in cool weather it’s not that hard to stay plenty warm.  Our extremities still need protection from the wind (so, toes, fingers, ears) but everything else tends warm, after we have physically “warmed up” to the exertion.


This is a little odd, but one thing people miss is that when you bike there is a lot of airflow.  Yesterday I biked in 95F-ish temperatures, about 40-50% humidity, and as long as I was rolling, actual physical exertion in that heat was still comfortable.  Rolling along at 12mph, or 18 feet per second, I sweep through about 10 square feet of air (crudely, 2 feet by 5 feet), for 180 cubic feet per second of ventilation, or 10,500 cubic feet per minute.  That’s about 5 20-inch box fans on high, all aimed at me.  At the same time, in the winter, because of this airflow, one of the most important ways to stay warm is to block the wind.

Double-counting bicycle time.

Because humans are not the finest motors, and because some (tasty!) food has a high energy cost, in some cases the end-to-end miles-per-gallon of a bicycle can be as bad as some fossil-fueled automobiles.  However, up to at least 100 miles per week, we get to double-count time/distance on a bicycle as exercise; time spent on the bicycle is time not spent at the gym, and calories burned on the bicycle are calories not burned at the gym.  So for example, five days each week, I get about 30 minutes of exercise before and after work, and then in zero time spent and zero energy consumed, arrive at work.  (To be fair, that is a lot of exercise, but it’s not wasted; there were measurable changes at my annual physical, worse from the low-commute Covid year, and then recovery to the better place in the next year.)  Energy expended at the gym also incurs a ventilation cost; to cool you down, gyms tend to be air conditioned and often include fans, where each fan consumes 50-100 watts.

And, the same as when you drive, you can also listen to podcasts or books on tape while you bike to work.

Typical speeds

People sometimes make wild estimates of bicycle speeds.  Cyclists who can cruise at 25mph are not common; well-trained cyclists can, but most people are not well-trained cyclists.  Even cruising at 20mph is not that common; I could, as a teenager, but it took a lot of practice, and I can’t do that now.  Sprints are faster, but similarly limited.  E-bikes come with various limits; the US federal law specifies two speed levels for assist, 20mph (still a bicycle) and 28mph (a “type 3” e-bike).  California state law uses these same rules, I think that this is the general plan for new e-bike legislation, especially the 20mph part.  But, for federal law purposes, if the assist can propel you faster than 28mph, then it is not a bicycle, at all.

Cargo capacity

Most people have a poor intuition for how much you can or cannot carry on a bicycle or a trailer.  Far and away the most important factor is the interaction of loads and hills; the greater the load, the smaller the hill that you will be able to manage.  Very low gears make hill-climbing with larger loads possible, but every rider has a minimum speed at which it becomes very hard for them to balance a bicycle, and there are physical limits on drivetrains.  On a cargo tricycle, however, balance is not a problem, only the torque limits of the drivetrain.

A second problem is managing the ability to brake; default bicycle brakes are sized for a default bicycle load.  Larger disk brakes and drum brakes help with this; managing downhill speed also helps with this.

On flat ground, the main limit is the rider’s ability to handle the load at very low speeds.  As the load gets heavier, more time is spent at low speeds, and the harder the load is to rebalance.  In practice I can pretty easily start and balance a load that weighs about as much as I do (over 200lbs), but I have also seen a video of someone riding a cargo bike loaded with 500lbs of bananas, and they needed help to get started.

Using a trailer avoids the balance problems, though the hill problems remain, and braking can be more difficult depending on how weight is distributed on the bicycle and trailer.  

Weird rules

Your intuition about what is or is not a “bicycle” may not agree with the law, which in turn depends on where you are.

The rules about what is a legal bicycle are a little odd, sometimes devolved to the states, and tend to differ in important ways from Europe.  So, at the US federal level, a “bicycle” is defined by its power and number of wheels; if it has no assist and 1, 2, 3, or 4 wheels, it is a “bicycle”.  If it has up to 750 watts of inhuman power assist, its assist is limited to 28mph, and 3 or fewer wheels, then it is also a “bicycle”.  There appears to be no US federal limit on “bicycle” width or weight.  But, if it has an e-assist propelling it faster than 28mph, then that is not a bike, that is not an e-bike, legally, that is some other device.

However, at the state level, there are a variety of rules and regulations, with a variety of e-assist power and speed limits.  California has rules that conform to the federal standards, with additional use requirements on so-called “type 3” e-bikes that have assist past 20mph.  As of this writing Massachusetts treats them as mopeds, though that may change within a month. New York State has a 36-inch width limit on cargo bicycles, with a bill proposed to increase that to either 55 or 48 inches, but that bill also includes a lower speed limit (12mph) and insurance requirement for e-cargo bikes.

Rules in the EU are more detailed and still evolving. Older rules limited assist for cargo bikes to 250 watts, which is completely inadequate for actual cargo in hilly places.  Four-wheeled e-bikes and e-cargo-bikes are legal.  The new rules allow more assist, but also have detailed remarks about brakes and bicycle durability.  As of that cited document, EU rules were silent on width, but Germany’s DIN has proposed regulations — 1m width and 250kg for 2-wheels, 2m width and 300kg for 3 or 4 wheels.

How to bike in Cambridge and Somerville (and perhaps other places)

Goals are safety, low stress, harmony with pedestrians and other micro mobility users.  This is informed by my experience biking through Belmont, Cambridge and Somerville daily for the last seven years, and biking through Belmont, Arlington, Lexington, and Burlington for nine years before that, recently exceeding 40,000 miles of commuting and errands.  I’ve also been biking long enough not just to have made mistakes, but to see patterns in my mistakes.  I collect a lot of video, note the sketchy bits, and sometimes review them.

I intended this to somehow not be as heavy-handed as I know it is, but this afternoon I was sitting on my bike on the sidewalk next to a bike lane, and as a pedestrian stepped into it to get to their parked car, the oncoming bike dealt with this by yelling “head up heads up heads up” instead of, say, slowing down.  This is exactly wrong, for reasons detailed below.  This whole thing has been bouncing around in my head for a while.

And, also, this is not the “best way” to increase safety and comfort, this is merely what you can do on your own.  Better regulations and better road design are both better choices than solo safety, but solo safety  doesn’t need focus groups or community meetings to approve it.

Edit: A second opinion, from a local Twitter friend who I hope to someday meet IRL. Scan down past my reply on Twitter for commentary. Some of the remarks will be interspersed below, in italics, either for emphasis or missing perspective.  One general problem is that the discussion of panic stops and stopping distance is not right, it could be better, but neither of us quite knows how. One particular issue is that “panic” stop is old-biker jargon; it means a really fast stop, which is a useful skill. Another issue is that the math is distracting, and the choice of numbers is not well justified. The TLDR summary of that flawed section could be: don’t ride too fast, learn to stop quickly, react sooner, not later, be aware that you can go over the handlebars if you stop too fast, so definitely wear a helmet when you practice stopping.  And, I didn’t say it because it’s as obvious as the nose on my face, never tailgate a car.  Bikes have a reaction time advantage, but cars have a braking ability advantage, and if they stop for something you can’t see (or out of malice), you have no reaction time advantage. Probably deserves its own discussion.

Existing traffic law is a poor guide

I don’t mean that you should ignore traffic law, and you certainly have to be aware of laws, but only obeying traffic laws will leave you exposed to various unsafe situations, and in some cases breaking traffic laws can lower your risk, principally from turning traffic, especially trucks.  Too much focus on the law causes you to think about blame, not mitigation, and any time spent analyzing a situation from a legal point of view (“is that pedestrian jaywalking?  If their foot isn’t in the road yet, am I really required to stop?”) is time spent not thinking about how to reduce risk.  No you cannot multi-task as well as single-task, the goal is to make the safest choice the habitual choice, and legal analysis gets in the way of that.  If you’re thinking about safety, your first thoughts should not include “what is the traffic law?”

For more on the ineffectiveness of blame, see Jesse Singer’s book There Are No Accidents and also the discussion of maritime versus airline safety in Charles Perrow’s Normal Accidents.

Practice safety and prevention

And by “practice”, I don’t mean, “be constantly stressed about”, but instead, cultivate good habits, make your usual behavior be the safer behavior, and make your snap reactions be the safer ones.  You’ll make mistakes sometimes anyways, but you’ll make fewer mistakes.  (I made a mistake today, I apologized a whole darn lot to the pedestrian that I did not hit.)

  • Look for “I’m about to ride where I can’t see what’s coming” situations, and be prepared to stop quickly and completely.  Properly designed infrastructure ought to make these rare, but, ha-ha, this is a guide to biking in Cambridge and Somerville.  It’s common for us to have loading zones with trucks in them completely blocking the view of a crosswalk or intersection.  Someone might step or drive out from behind that truck (I have video).
  • Learn to pass behind; whether cars, other bikes, or people, they all tend to start or keep moving forward more often than moving backward, passing behind reduces the chance of a bad interaction, and removes the need for a negotiation about who goes first or speeds up or slows down.  It’s just simpler.  Another reason:
    “The passing behind advice: good, but I also prefer keeping a bad driver in front of me vs me in front of them; if they’ve done one dumb thing when I could see, I assume they do dozens more dumb things every hour. If I’m behind them then they’ll have a harder time affecting me.”
  • Train yourself to react to emergencies by braking first, and practice braking so your panic stops don’t turn into headers.  Upright posture helps with fewer headers, so does a heavy bicycle, especially if it is loaded to the rear.  Braking even a fraction of a second early can make a big difference; an extra half second at half a g (a best-case hard front wheel brake) can cut your speed by 8 feet per second, or over 1/3 at 15mph (15 mph/22fps -> 10 mph/14fps). The goal is not to be tense about this, but just to turn it into a habit, so that your snap reaction is the safer one.  Swerving can also work but swerving requires that you not swerve into something else — this is more complicated that braking.
  • When in doubt, slow down. It’s a mistake to try to “zip past” a sketchy arrangement of cars and pedestrians.  Doing that just adds to the sketchiness, adding speed makes crashes hurt more.  This is a hard habit to break.
  • Don’t treat your bell as an emergency safety device.  Brake first.  Don’t try to convince yourself that you can do both just as well as one, no, you cannot.  Bells are low-bandwidth, useless for signaling drivers (their cars make them deaf), and pedestrians aren’t required to be listening, able to hear you, or paying attention.  Braking is one reaction time away, bell-ringing means the response is at best two reaction times away.
    “Also triple OMG yes about bells. I think bells are good for a quiet path when you’re like 100 feet away. If you’re close enough to talk, do that. Jeez. Instead dudes (almost always dudes) think it’s a “GTFO” signal.”
  • Don’t expect other people to do more than obey the law.  Don’t delude yourself with expectations of what other people “should” do (should control their dog “better”; should not wear earbuds; should wear reflective clothing at night on a shared-use path; should pay more attention to their toddler).  Those things are not even the law, why would you expect people to obey not-laws when they break actual laws often enough?
  • Slow and wide for pedestrians everywhere. In a bicycle-pedestrian crash, the person on the bike is at greater risk, but it’s them that brought all the energy to the crash, not the pedestrian.  Pedestrians are inherently safe, even more so than bicycles.

 Don’t optimize for top speed

This is not obvious if we just react to how we feel about being passed, especially close-passed, but if you are merely bumped by a passing car or truck and lose control, higher speed is not on your side.  You can also see this by looking at relative trip risk between motorcycles and bicycles; the per-trip risk of death on a motorcycle is TWENTY-FIVE TIMES HIGHER, despite the louder pipes, despite the brighter always-on headlights, despite the greater mass and stability of the motorcycle, despite the better and in-most-states legally-required helmet.  There is a speed somewhere between typical bicycle speed and typical motorcycle speed at which adding speed makes things more dangerous, not safer.  It might not be a very high speed, maybe as low as 25mph, maybe a little less.  I think it is telling that European E-bikes are assist-limited to 15mph; the Europeans are much better at road safety than we are, and they chose 15mph, not 20mph.

Higher speeds hurt in several ways:

  • Drivers aren’t expecting bicycle speeds above 15-20mph; they will be surprised, perhaps angry, perhaps unsafe.  You will have a better experience at a slightly lower speed.
  • Crashes get much worse between 15, 20, and 25mph.
  • Stopping distances increase dramatically with speed, even bicycle speeds.  My best-case stop at 15mph (0.6s reaction time, 0.5g braking) is 28 feet; at 23mph, it’s about about double that.  Braking more sedately (0.25g, a skidding rear wheel), 15mph results in a 43 foot stop, 20mph needs 71 feet, 23mph needs 91, and 25mph, 106.
  • That stopping distance is the minimum you need to scan for surprises; you can do a much better job of that when it’s 30 feet, than 60 feet.
  • Resist the urge to attain maximum speed down a hill.  Instead, bust your ass on the way up (on a commute, that produces the maximum time savings for a given amount of sweat) and rest and recover coasting downhill. But beware “workout brain” clouding your judgement after a hard hill climb. (Yes, this is a real thing.) 

“The part about speed is good, the analogy to motos is great and you should press the point about ebikes more IMO.

I disagree that drivers aren’t expecting bikes to go above 15-20mph, I think it’s more like 10-15 just based on interactions. ¯\_(ツ)_/¯”

Identify and avoid bad roads and dangerous vehicles

  • Multilane roads are a bad idea.  Drivers are more distracted because there is more going on, some of them will use the second lane to drive fast and/or accelerate unpredictably.
  • Door zone bike lanes in non-residential areas are a bad idea;
    Door zone bike lanes in permit-parking-only are less risky;
    Pay attention to folded-in mirrors (good), lit brake lights (bad), Uber/Lyft stickers (bad), and taxis (bad) and cars with New York “T&LC” limo plates (very bad);
    Riding fast in the door zone is a bad idea.
  • Trucks with large exposed wheels are deadly.  If you don’t feel comfortable with one approaching, leave the road.  Don’t depend on the driver, their truck is not designed for your visibility or your safety, they may not see you (and that’s certainly what they’ll claim if they hit you, and the police will believe them).  Yes, the whole situation is completely appalling, European regulations make big trucks somewhat safer, but in this country we have other priorities.

If you got this far, thank you for your patience.