The countersteering can of worms

Eric and Geoffrey are asking some tough questions regarding Countersteering a cross bike (or any bike)?

They want to know whether a gyroscopic force exists in countersteering, how bikes differ from motos, and how they can use all this mumbo jumbo to go faster.

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Eric Says November 18, 2010 @ 9:58 am

A fine point that I’ve been wondering about related to countersteering. To turn a bike we’re told to push the inside grip into the turn. The result is that the bike leans and we start turning. But is this action a result of gyroscopic forces (like in the above diagram) or is it simply that the bike is light and we can directly lean it by moving the inside grip towards the ground? And are both of these actions “countersteering”?

I can very easily feel this “push left to go left” effect on a motorcycle. Push the left grip forward and the bike leans left. Push it more and the bike leans further. On a bicycle, it feels noticeably different even at high speed, no doubt because of the difference in mass/inertia between the two machines. In which case, at what point do the dynamics of the situation transition from “bicycle” to “motorcycle”?

And, more importantly, how can I use all of this to go faster?

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Geoffrey Says November 18, 2010 @ 2:24 pm

Actually, it isn’t gyroscopic effects. If you hold a bicycle still, and turn the handlebars, the bike will lean. It’s simply a mechanical thing, based on the rake of the fork.

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Eric Says November 18, 2010 @ 2:31 pm

Agreed. I was trying to be consistent with the terminology of the original post, but you’re right, you can hold the bike stationary and observe this mechanical response, so it’s not a gyroscopic thing. I do still wonder if there are two fundamentally different techniques on a bicycle. Turn the handlebars, bike leans. Or, lean the bike and the handlebars turn to match the lean angle.

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What I think

Can of worms!

Like I said in Countersteering a cross bike (or any bike)?, I rarely address countersteer because it balls people up.

Countersteering leans your bike in two ways:

1) Say you want to turn right. If you steer left, your body keeps going straight, and the wheels go to the left. This creates a lean to the right.

2) When you bump the bars to the left, gyroscopic forces do indeed lay the bike over to the right. (Consider a dirt jumper laying his bike into a flat table.) This gyroscopic effect is most evident at high speeds with heavy wheels. It’s an essential part of cornering on a street moto that weighs a lot more than its rider. You can feel it on a mountain bike too. Get some speed and give the bars a little bump. You’ll feel the bike lean over immediately and powerfully — much more violently than the pure mechanical response. Try it.

Bike vs. moto

The faster you’re riding a bicycle, and the heavier its wheels, the more it handles like a moto. But keep in mind:

My Honda VFR weighed 500 pounds. My Enduro weighs 30.

The only way to flick that Honda (or the huge BMW tourer I rode around Italy) was with gyroscopic countersteer. With a much lighter bicycle, you can physically lean it below you.

How to go faster

On the bike, focus on pushing the inside grip down into the turn. That sets the bike’s lean angle quickly and precisely. The steering column corrects and — bam — you’re railing.

But consider this: If your shoulders are behind your handlebars, when you push the inside grip down you also push it forward. So you’re physically leaning the bike below you AND you’re getting some countersteer.

In the real world, I think these forces get all tangled up. Concentrate on setting angles deliberately and precisely. You will corner better — and go faster.

CAN OF WORMS!

— Lee

Know more. Have more fun!

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13 replies
1. josh130 says:

This is some complicated physics, but there is definitely a “gyroscopic” effect. If you hold a spinning wheel and try to twist it, like you are steering, it will not only turn but also try to lean. I am not sure how useful this is when riding a bicycle because of the low weight and speed. For example, even motorcycles only need to be conciously countersteered above about 15 mph.

How do you go faster? Stop thinking about gyroscopes and ride!

2. Geoffrey says:

Back again. :). Anyway, I have experienced the gyroscopic effect, doing the experiment of sitting on a stool holding a spinning wheel. Tilt the wheel, and the stool spins.

Lee, thanks for the high speed cornering tip. I’ll look to rail on my ride to work.

When I get a moment (Ha! Moment! Inertia pun!) I’ll run some math and look at forces. I’m now immensely curious.

Geoffrey

3. leelikesbikes says:

I think it’s cool to know this stuff, know how to control it, then … stop thinking about it and ride!

4. Scott says:

I don’t believe there’s enough gyroscopic force to do much in a bicycle. A good experiment to try (I don’t have the skills) is to hold a low manual at speed, then turn the bars. Does your bike suddenly lean hard?

My opinion is that countersteering mainly involves moving the wheels out from under the center of gravity. Someday, I hope that someone writes the definitive analysis of countersteering. Partly because I think all the talk of gyroscopic forces and other esoteric causes is what gets people balled-up. If countersteering is simply seen as “in order to lean left, I have to move the wheels to the right of my body”, then it’s not so confusing or counterintuitive.

I guess the other thing that confuses riders is that countersteering isn’t a method for turning; rather it’s a method for initiating a turn. Or even more precisely, for initiating/modifying a lean. The term “countersteering” sounds too much like what one would do in the steady-state middle of a turn.

That said, when riding I also use the simple mnemonic of “pushing down” on the inside grip to initiate a turn. It feels direct and efficient.

Keep up the good work, Lee.

-Scott-

5. josh130 says:

The problem with the manual theory is that the wheel I being rotated in a different plane and so the bike doesn’t want to lean it wants to twist… like a bmxer doing a tabletop. Also anyone skilled enough to try it would be to skilled at balancing to notice the change before they corrected for it.

Scott is right though, countersteering controls lean, it doesn’t make you turn. That means you do it at the beginning of the turn and then let the bars correct themselves. On a MOTO you can set the lean and then take your hands off the bsrs. The bike will keep turning!

6. leelikesbikes says:

Also regarding the manual experiment: When you manual, you drive significant weight into your feet. Your legs will be somewhat braced, and I think that would keep the bike on line.

You guys are totally right on this notion:

– Set the lean angle using whichever means you choose.

– Let the steering column correct.

– Rail it!

7. WAKi says:

I have a question about railing here: two parts have been covered here, and I think I got the fundamentals, the turn entry, and doing the turn itself – the exit is my pain… especialy in burms. I totaly get it with counter steering that fast push on the inside of the bar makes the bike roll on the burm top. I can get into the burm very fast, direct the force out by pushing on the bars, feel the force pushing me into the burm giving endless grip, but as soon as the burm ends… blurp! I fall to the inside, I can’t do this PRO thing when they have this front wheel turned brutaly to the inside which i guess makes them com back to straight after leaned corner/burm. My body must in some wrong place over the bike as I can’t find the movement with my bars to pull them to the inside. I can do that slowly i.e on pump track but not when on dh track. Any tip here on the exit? THanks!

THX!

8. leelikesbikes says:

>> I can’t do this PRO thing when they have this front wheel turned brutaly to the inside

To me that shows the front wheel is steering and sliding. It looks cool, but I don’t know how useful it is for most corners.

It sounds like you’re not disengaging from the berm. You need to lean as you enter and straighten as you exit.

9. Feldy says:

Geoffrey’s has got it mostly right. Counter steering works because when you turn the bars to the right, the bike leans to the left. A bike that’s leaning to the left will turn to the left unless you force it not to by leaning the other way with your body. The maths isn’t really all that complicated and it’s pretty clear that the torque arising from leaning over and gravity beats that of the spinning wheel. Incidentally, Lennard Zinn knows a lot about this stuff, and has a pretty coherent explanation, but I’m not sure he’s ever published it.

Lee, frankly I’m shocked that you shy away from this topic whist geeking out on so many others. ;-D

As winter’s coming in, perhaps we should discuss at the Golden Bike Park sometime — after my wrist heals from backcountry skiing shenanigans, that is.

10. leelikesbikes says:

Feldy is a physicist, so there.

Yeah man, let’s geek out at GBP.

11. WAKi says:

aaaa maaaaaan! For me that was more “pinkbike sick” than Zinks 360 on Rampage. Thanks for sharing, I can’t even express how awesome that is! Now I know a bit more about what you meant in the interview with James Wilson with Pumping as the way of life. DEMN! That’s it! I am buying the second edition of UR book…