I did a round of noodling in a spreadsheet to try to get a feel for how different ways of carrying people or cargo damage roads. The formula for damage is the sum of the cubes of the wheel loads; crudely, the gross weight of a vehicle cubed, divided by the square of the number of wheels. This can lead to some pretty non-intuitive results — city buses in particular are non-intuitively bad for roads .  Overall the most surprising thing is that even when results are calculated either per-passenger or per-pound, you end up needing a log scale to display them meaningfully; heavy vehicles are that bad for roads.

I’m not quite sure what to do with this information; there are other things to optimize for besides road damage.  For example, it would not surprise me in the least if a semi-trailer were more fuel-efficient per-pound than a human on a bike; bikes are efficient, but we do have to eat to run them and food is quite often energetically costly.  Similarly, though bicycles are far safer for pedestrians than cars and trucks, per pound of cargo they will lose most of their advantage against delivery vehicles (the comparison is quite tricky; a cargo bike can easily carry 100 lbs in addition to its rider, and 250 is not out of the question, and such large bicycles are even less likely than “normal” bicycles to travel at pedestrian endangering speeds.  Contra that, a human pedaling a loaded cargo bike has an incentive to not stop because it takes quite a lot more energy to bring that larger weight back up to speed).

Note that a single-occupancy vehicle still fails badly on efficiency and safety metrics, but trucks of various sizes need not.


I’m a little reluctant to post this because it’s got a bit of a gloating feel to it (“look at my massive calves and thighs!”) but people should understand that if they don’t have the opportunity to bike to work, they’re missing out and they’re being cheated. That means they have to know the sort of thing that they’re missing.

This doesn’t necessarily work for everyone, but it’s clear that most people are suspicious of doing things because it’s supposed to be good for the planet. Instead, I’d like to suggest reasons for biking to work because it might be good for you. I’ll try to be concrete.

I am 55. I weigh between 220 and 225lbs, and I’m 6 feet tall. That makes me officially quite overweight. I hate dieting and so I don’t really do much more than try to keep sweets out of reach. Beer is a regular part of my diet, and food is free at my new job. I weighed more before I started biking to work 9 years ago, but in the last year I started biking even more.

My commute to work, since March, is 6.1 miles by the fast, direct, and less-fun route, and I reliably do that in 30 minutes on a bike without running red lights. At rush hour biking is faster than driving. If I am in a hurry I can do it in 26 minutes, though I may end up sweaty (all I need to go faster is to breathe more; the legs just go as fast as oxygen debt allows). Traffic jams are not a problem; I ride through the gaps and go almost as fast. Parking is not usually a problem (we do almost fill the bike cage at work, but less so now that the weather is cooler, and there is other parking). If I instead take the less-annoying route, biking takes about as long as driving, but not longer. Oh yeah, my bike weighs about 65lbs.

Since March, I have gained over a centimeter in circumference in my thighs, a centimeter in my calves, and I’m regularly pulling my belt a notch tighter. Even before the new commute when I was biking somewhat less per week, I still had enough wind and stamina to shovel snow like a machine; I expect it’s rather better now because the new commute includes more sprints that punch my heart rate up a bit.

So. Would you like a faster commute to work, no parking hassles (and it’s FREE), a little weight loss, a slightly smaller waist, more muscles, and enough wind to shovel snow without fear of heart attack? If your commute is like mine, perhaps you should ride a bike. If your commute is about as long as mine but too unpleasant for you to tolerate, have you considered pestering your local government for some combination of better enforcement of traffic rules (if it’s speeding cars that make it unpleasant) or a reasonably sized lane in which to ride your bike (or perish the thought, a segregated path or lane)? Failure to provide you an adequate place to commute by bicycle is depriving you of a faster commute and measurable improvements in your health and fitness.

And do understand, if you want this and your roads don’t allow it, you should be angry. If I had to give up biking to work I’d be very unhappy. Statistics say this would increase my annual risk of death by about 30%. Do you think it is reasonable to live with that kind of extra risk? Do you have any idea how much larger that risk is than all the risks that usually get people all wound up and excited? That’s not an acceptable status quo.

One warning; if you’re out of shape, your first commutes will not be as fast or as fun. It’ll take about a month and a half to get over that, and then there will be gradual improvement for a few years — not necessarily faster, but one day you may find yourself regarding hills as merely annoying, instead of as an obstacle to go around. Eventually you’ll learn to run up an oxygen debt charging up hills and then rest on the downhill, because that is fastest, and because one day, you can.

Anyone who takes this seriously, if you’re looking for a bike, you could do a lot worse than a 3-speed with fenders, chain guard, dynamo hub, and fat tires. The fatter the tires, the better; you’ll be more comfortable, at less risk from potholes and road cracks, and you’ll spend less time pumping up your tires because they’ll hold their air longer. If you’re gung-ho, get a cargo bike, either an EdgeRunner , Yuba, Big Dummy, or a Gr8, or maybe a Kr8 or one of the several other USproduced cargo bikes.

Parcel delivery robots

December 12, 2015

I was thinking about how we would deliver goods in a hypothetical ban-cars world, and realized that people on bicycles carrying stuff are not a bad model for what robots might also deliver on vehicles of modest size. Because we don’t normally see huge deliveries on small vehicles we tend not to think that it’s possible, or even when we do see it shuffle it into the ignorable category of “crazy”. But it is possible and it happens, whether we believe it’s “crazy” or not, and if you want to think about what a small robot vehicle might be capable of, it helps to remember that a human is a somewhat idiosyncratic 250 watt motor, and that a robot running a 250 watt motor and carrying 100lbs of batteries has similar capabilities.

So, what can humans carry on bicycles?

Haley Trike and 400 lbs of sand (video)

a chicken coop

a trailer full of Citibikes

a ludicrously large pile of stuff

a mattress, table, chair, and box

People carrying that much stuff don’t move very fast, but they move, and there’s no particular reason for a robot to travel quickly either; there’s no driver being paid by the hour, and it reduces the risk and severity of any possible crashes.

This is a half-baked theory based on no particular expertise of mine, but I’ve been reading and thinking about safety for a while now (perhaps decades).  I have come to think that one contributor to driver irritation with cyclists is that drivers are already driving about as fast as they can think (if not faster) and the sudden appearance of something out of the ordinary like a cyclist in traffic is the straw that breaks the cognitive camel’s back; the driver is no longer able to keep track of everything that is going on and they don’t like it.

Several things led me to this.  One was things like the awareness test video, where it is made obvious how our attention can become so focused by cognitive load that we will overlook what is right in front of us. Another is my use of daytime running lights; I started doing this years ago because when I built my own lights I left out the off switch (it’s just another point of failure).  With lights on all the time I am more visible and less likely to surprise, and it seemed that I had many fewer unpleasant interactions with drivers.  They were still often-enough clueless and no more likely to obey traffic laws, but they seemed to almost never be angry with me.

A third thing is the experience of riding the bike itself.  My bike is relatively tall (has a high bottom bracket) and I am slightly tall (6′) I am riding upright, and rarely going even 20mph.  I can see around me much better than when I am driving, and because I am almost always moving at a reasonable pace I have plenty of time to consider what I see.  And once you get used to this, the lack of it is unpleasant — when I’m driving, I notice that I’m deaf, and I don’t like it (I roll down the windows, whatever the weather — what’s more important, safety, or not getting a little rain blown in the window?), and I notice that I’m short and can’t see as much, and I don’t like it, and I notice that stuff is happening too quickly to pay proper attention to it.  I think most only-drivers are accustomed to a different baseline than I am, but when they fall off that baseline they don’t like it, same as I do, and blame the distraction for their irritation.  In my case, I blame the car that I am driving, in their case, they blame the cyclist, pedestrian, or whatever it is that happened to cause their cognitive overload.

Another application of this is in devising safety rules.  One rule that serves me well on my bike is to count the number of potentially unpredictable things (dogs, small children).  One is usually not a problem because I can swing wide of it.  Two, I should slow down some, depending on details.  But three is more than I can reliably track; I should slow down to a walk, if I cannot put a safe distance between me and the children/dogs.

Or, when approaching a crosswalk with pedestrians in it, how do they know that I intend to stop?  Sure, I could slow down, but that means that they have to track me long enough to know that I am slowing down, and what if I wait till the last minute — that all combines to add an unnecessary cognitive task for those pedestrians.  That’s rude.  So I slow early so it is easier to see that I know I should stop, and I signal so that they don’t have to track, and I aim the bike behind their path so they can see that I think they should be crossing.

Field trip to NYC

October 1, 2015

So I’m attending a conference in NY on Friday, took the train down Thursday and spent the afternoon at the NY office, took Citibike to get there from Penn Station and then back again to the hotel.  Most of my riding was on 8th and 9th Avenues, which have nice segregated bike lanes.  I observed the following:

– sidewalks in NY are too small.  Pedestrians regularly spilled over onto the bike lanes, and it’s because the sidewalks are crowded.  Obviously the sidewalks need to be larger, because we cannot make pedestrians smaller, and they are the overwhelming majority here.

– no matter what anyone says, bicycles are not terrifying relative to cars.  I didn’t see any pedestrians walking in the flow of traffic because the sidewalks were too small.

– salmoning is about 100x more common here than in Cambridge (MA).  I see it there in-my-face about once a month, here, I’d say at least a dozen times in less than an hour of riding.

– in the places where the bike lanes were not segregated (by a line of parked cars) everything dissolved into nonsense.  Cabs drove in the bike lane, bikes rode in the cab lane.  The should rip it out and do it again.

– but where the lanes were segregated, it worked really well.  It was quite comfortable, I did have to take care to not hit people on foot, but that’s not hard (I’m on a Citibike, not exactly racing along).

– cars driven in NY should have their horns removed.  I know the horn law in this state, horns are only for safety, “the light is green but you’re not moving” is not a safety issue. Period. (Go ahead, try to argue the case that it is, make a fool of yourself.  Stopped cars are the safest cars.)

I saw the arguing aftermath of a pedicab-bike collision — didn’t understand why on earth the guy on the bike was pressing the point because I saw nothing hurt and nothing broken, but he was.  I blocked more than one NY taxi from making a right turn when it came into conflict with the bike lane.  I saw one person on a bike who was trying to make a big deal about clearing pedestrians from the bike lane (“ha ha, she has got to be kidding…”).

1000 miles to the new job.

October 1, 2015

(written in July, now it’s October) I got a new job 4 months ago, now in Kendall Square all the time.  I only bike to work, unless I work from home (done that 2 or 3 times so far) and I even commute by bike when I visit the mother ship in Mountain View.  In 4 months I accumulated just about 1000 miles to work, a combo of neighborhood streets, bike lanes, cycle track, sharrows, and fitting in wherever it is appropriate.  October update — 1750 miles now, about 250/month, and writing this from NYC where I rode Citibikes to/from the NY office today.

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I’ve noticed that car drivers on the internet often think they are qualified to lecture “cyclists” on how to be safe. This is ludicrous, given that the average driver is 10 to 20 times as likely to kill a pedestrian as the average cyclist, with a similar ratio for serious injury, and the cyclists are mostly car-owning licensed drivers anyway. “But cyclists break traffic laws”. Number one, they only do so about as often as drivers – people are people, we all make mistakes and take shortcuts, and we all also overlook the faults of our own tribe and are hypersensitive to those of “the other” – and number two, if you really think that cyclists DO break laws at some unusually high rate, then that means that laws have not much at all to do with true road safety. Recall that bikes are 10 to 20 times less likely to kill or seriously injure pedestrians than cars – that’s safety.

So, if cyclists don’t obey laws, what do they do that makes them so much safer? And wouldn’t it be great if drivers knew about this, so they could do these things too, and be much more socially responsible? I’m sure they’d really like to know, so I will BikeSplain safety for them:

  • around bikes and peds, 20mph is plenty. Not 21. 20. And in general, never build up speed you don’t need; if the light is red, why not coast as soon as you see the red, instead of going fast and then braking at the last moment. Speeding-then-braking is a waste of energy and poses unnecessary risk to others.
  • do not use a larger vehicle than necessary for the errand. 100lbs (a large cargo bike) is adequate for 3 kids, groceries, etc, if you’re only traveling a few miles. This holds true even when choosing one car over another, if you have a long or hilly errand, or if you are handicapped in some way; an SUV is over 3 times more likely to kill someone else than a regular-sized car.
  • windows down, stereo off. You need to be able to hear what’s going on around you. With the window up and stereo on you’re effectively deaf, and you’re certainly less able to hear than a cyclist using earbuds (yes, someone has tested this).
  • if you’ve been drinking, it’s good to always pass a small challenge of coordination before embarking on a journey to be sure that you’re sober enough to drive a car. For example, if you cannot keep a bicycle upright for more than a block or two, you are surely too drunk to drive. So if you’ve been drinking, even a little, be sure to ride a bike first as a test to see if you’re sober enough to drive.

Almost every cyclist on the road obeys the rules above, and that’s the main reason why they’re so much safer than drivers. The one exception is people who are training to race – they often travel faster than 20mph and are less safe for pedestrians, but fortunately they are a small minority of urban cyclists.

Many cyclists follow additional safety rules to otbain even more safety. I use these rules myself, and I’ve seen other people do the same:

  • never use your horn or bell. Use your brakes instead. Think about all the stuff that has to go right for your horn to make things safer, versus the certainty that you see something going wrong and could start slowing down right away to either prevent it or mitigate it. With the windows down and stereo off, you might be able to even talk to the people around you.
  • if you can imagine a potential crash, act to reduce its risk and/or mitigate it if it occurs. No free pass just because you think the other guy is breaking a law. How sure are you about traffic laws? And so what if they are breaking the law, is dead an appropriate outcome? Is that guy with the leaf blower going to stumble backwards into the road? If you see a teenaged boy on a bicycle or driving a car, what are they odds he might do something irresponsible? Drive as if that might happen, and be prepared to keep it from causing a crash.
  • reduce speed limit by 5mph for each child/dog (up to 3) near your path, i.e., 15, 10, 5. It’s unlikely that you can keep track of 3 unpredictable moving objects at once, and even trying will distract you from everything else you should be watching. So slow down, to give yourself more time and to mitigate the harm of any crash that might occur.

In the spirit of “Same Roads, Same Rules”, I think these are good rules for everyone to follow, both in cars and on bikes.


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