Bicycle science

@NiclasMattsson said:

Apologies in advance for going completely off-topic, but you stumbled into my favorite trivia subject: the science of bicycle riding. I’m obsessively compelled to share two potentially mind-blowing factoids. (If someone is tempted to reply, please open a new thread in the off-topic subforum and @call_me so this thread doesn’t get derailed.)

ThreeFour bike topics that seem to get folks all riled up are:

  • You always use countersteering when turning,
  • Loading weight on the bike will decrease tension in the lower spokes,
  • Using the front brake only stops you the fastest! (assuming safety bicycle, good traction), and
  • Cars can stop about twice as fast as you can. (again, some assumptions …).
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Just to throw a wrench into this thread really early on:

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Very cool! I’d seen the bike (or a similar one) described before but not this video.

I bought a fixed-gear bike a few years ago and it took about three rides to get rid of the habit of ceasing to pedal at various points in time. Then I rode it exclusively for a couple of months. The next time I rode a normal bike, as I approached a stop sign my chain broke. Actually no, it didn’t break, but that’s the first thing that came to mind when my feet stopped turning over. I’d developed a habit of smoothly transitioning from pedaling positively (making positive torque like normal) to pedaling negatively, and when I did that on the regular bike and my feet stopped it felt absolutely wrong. However, after going back and forth between bikes a few times, I can’t generate that feeling of wrongness anymore.

Brains are amazing.

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Thanks for the amazing video. Some brave rider may try to write the equations of motion for this “backwards” bicycle…

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This reminds me that I should not postpone putting on my winter tires much longer. The problem is that both those and the summer ones are Schwalbe Marathons, and they are tough and unforgiving, so it is a ~30min exercise and I always procastinate and hope that winter will not happen for some reason.

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I have to admit I’m a fair weather rider! Lots of hills here and 10 kph climbs and 50 kph descents require rather different clothing!

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Do you have a good experience with your marathon winter tyres? I understand you install them at the beginning of winter, and keep them until spring… are they ok to ride even when there is no snow nor ice? Also, are you cycling on asphalt roads or on dirt tracks?

I’ve been thinking about buying a pair of those, but given that there usually aren’t more than a few days/weeks of snow where I live, I haven’t bothered yet.

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I have the same tires. They don’t give a ton of extra traction in snow, but the true danger is an unexpected icy patch, and they work like a charm on ice. I procrastinated putting them on a few years ago and quickly regretted it when I ran over a patch of hard-to-see ice and took a dive. Highly recommended for winter biking (more for ice than for snow), even though they add a bit of rolling resistance and prevent aggressive turns on asphalt thanks to the studs.

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Yes, I have the same experience as @stillyslalom. I put the spiked tires on around end of November and replace them in the spring. In Vienna, they are needed for around 30–50 days at most every season, but they are OK to ride on bare asphalt too (not super fast, but winter biking generally isn’t about that). They are meant to cope with the the ice patch, which is the most dangerous.

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I bike through the winter in Edmonton and it lasts a bit longer than ideal. I should really look into studded tires, mine do not perform well on ice at all.

I usually end up on my butt at least twice per winter.

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You don’t need a special bike for this experience… just bike with crossed arms, left hand on the right handle etc. It’s doable with a bit of brain twisting.

No, not according to the video: https://www.youtube.com/watch?v=MFzDaBzBlL0&feature=youtu.be&t=122

Try to ride your normal bike with crossed arms and report back… (don’t hurt yourself)

There is this very nice book by Max Glaskin:

Glaskin, Max. Cycling science: how rider and machine work together . University of Chicago Press, 2013.

It covers various subjects from aerodynamics to bicycle stability and more, it’s sometimes a little light on the details but very pleasant to read. I think the authors also has a blog and more recent material.

Also, there is this bicycle dynamics research lab at the Technical University of Delft, in the Netherlands: http://bicycle.tudelft.nl/schwab/Bicycle/
I think some of their initial research was on why bikes are stable (spoiler: it’s not the gyroscopic effect), along the lines of this story: https://www.nature.com/news/the-bicycle-problem-that-nearly-broke-mathematics-1.20281

They have very entertaining videos of their experiments on stability but I have not followed their more recent projects.

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