Hmmmmm? photo: @fat cyclist
This is perhaps painfully obvious to everyone but me and if so, sorry I’ve yet again wasted your time. The other day, after falling off another floating board in the ocean I had to admit my balance might suck. And my coordination too or I might have been good enough at baseball to actually like it and play it. Nope, ball sports are right out. What I want to celebrate is the fact that our bikes have two magic gyroscopes spinning underneath us. You want to sit up at 40 kph, casually reach behind and tuck your gilet under your jersey? Be my guest but you can only do that because of the gyroscopes, not your awesome balance. If good balance was required to ride bicycles every prat and his brother wouldn’t be chatting on their iphone while zipping down the lane.
Descending at great speed is so damn much fun because the bike is rock solid when hauling such mighty ass, until it isn’t and that is is pilot error, not the fault of your dualing gyroscopes. To quote one of Maine’s greatest exports, Yvon Chouinard, “speed is safety”. He was talking about mountaineering and the need quickly get across exposed couloirs to avoid potential rockfall or avalanche but it’s also true for cycling, to a point. OK, he could have said speed is stability if he was more of a cyclist.
Does this mean we shouldn’t own deep section carbone wheels, with their lighter rotating mass providing less momentum? No, folly my friends, the deep section wheels are spinning faster because you are going faster due to the aero-awesomeness of those wheels. A year into my tubular tire/50 mm Cancellara carbone wheels and I’m more chuffed than ever about them. Unless it’s raining heavily and I’m descending then, not as chuffed. But I digress, that is another lecture.
So far so good. What the hell is absent minded professor talking about? All this spin angle momentum and torque should have us riding in circles not going in straight lines. That is your weekend homework. Test on Monday. Buon weekend.
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Is that a serious question?
Okay, since I'm a high school physics teacher for my day job, I'll take a stab at this.
Classical mechanics can be divided into three broad families: motion in a straight line, motion along a curve (which is really just motion in a straight line plus directed acceleration), and rotation. Most people who study physics spend way more time on motion in a straight line; it's easier to see and visualize. One of the sub-categories of straight line motion is momentum. It's the idea that something moving in a straight line has a strong tendency to keep moving at the same speed, and in the same direction, unless something else comes in and messes with it.
Thankfully, all of the ideas in straight-line motion have their analogues in rotational motion. The analogue to momentum is angular momentum. A thing that is rotating has a strong tendency to keep rotating at the same rate of spin, and in the same direction, unless something else messes with it. The trick here is that the direction of rotation is not just the top of the wheel going "forwards" -- think about the direction that the axle is pointing. That's what we think about when physicists talk about the direction of rotation. And that direction has a strong tendency to keep pointing in the same direction, in three dimensions, creating the "gryoscopic effect"...
...and letting all of us think that we're more graceful than we really are.
Unrelated: if we were to expand the hierarchy to hardmen in general, Yvon Chouinard deserves a place in the "Awesome American Guys" canon.
On the insignificance of the gyroscopic effect when riding a bicycle.
I read the article, and the first few comments, aaaannnnndddddd I still have no idea what you're on about !
Ohh is that the time,
I'm still too scared to go no hands. Unless the brake cables come out on top of the hoods and the gear levers are on the downtube.
I'm going to hang out with Julius over the weekend!
Why is it so?!
@sthilzy
Damn that takes me back.
And now I have an unaccountable urge to buy some Cadbury's chocloate.
@cognition
@hudson
It would be a lot better if I could show you stuff in real life, or at least diagrams drawn on a board.
But if you want to check it out, take a front wheel. Hold one side of the quick release, then use your other hand to set the wheel spinning (faster is better, same as in The Rules). After the wheel is spinning, take your second hand and hold on to the other side of the quick release. Now try to change the direction of the axle. You'll feel -- strongly -- the resistance of the wheel to changing direction. That's the gyroscopic effect.
@Cam is correct, too, though, about that study. I didn't want to get into it because I didn't want to geek out fully. But what the heck! The author in the study builds a bike that can basically hold a second front wheel (off of the ground), sets the second wheel spinning the opposite direction, and observes that the bike is still rideable. His postulate is that the trail of the bike is what keeps it stable. I haven't done the experiment, but it looks solid. I'd love to set up some kind of arrangement where I could get two wheels linked together similarly to his pair of front wheels, set them spinning in opposite directions, and see whether they're easier or harder to torque off-direction. My analytical sense is that it should be easy, but my intuition wonders whether it wouldn't be twice as resistant. Something to rig up for next year's class, perhaps...
@cognition
Well, and mind you it come from someone wildly incompetent, since the axle is hard to move in both directions, a second wheel pointing the same direction but in reverse would also be hard to move in the same both directions.
A second wheel off the ground but perpendicular to the one on the ground would be a mess tough.
Am i making sense?
@LeBelge
I think so. Imagine a doubly-long quick release that would let you put two wheels right next to each other. My question -- and I think yours, too -- is whether two wheels spinning in opposite directions would be more stable, or whether the two vectors in opposite directions would cancel each other out.
I genuinely don't know. My analytical intellectual sense says that they would cancel each other out. My intuitive sense thinks that maybe it would be twice as stable.