Do you need to turn the wheel for the bike to turn?

[SyuRi]

Simple question.

I’ve been having this discussion on another forum. They pointed me out to these links
Article One - http://thekneeslider.com/archives/20…he-no-bs-bike/
Aricle Two - http://www.soundrider.com/archive/sa…s/nobsbike.htm

Since i cant use the search button (for now :P) i don’t know if this is a repost or not. Sorry if it is.

Anyways, look forward to your answers.

[Mangetout]

Neither of those links work for me - I think it’s because you’ve copied and pasted their abbreviated text representations, rather than the full URLs

[Busy_Scissors]

Hi SyuRi, your links don’t work, not sure what the problem is with them. Anyhow, you’re talking about motorbikes right? I’m more of a bicycling man, but I think the answer depends on large part on the camber of the road surface. Certainly, to rail a corner on a bicycle on a normal road requires minimal steering lock - bit of countersteer then just lean the bike over. I don’t know about not turning the wheel at all - it probably needs some small degree of turn.

On a flat surface more turn is required, or it certainly feels like it. Someone will be along to give a more precise mechanical definition of what taking a corner on 2 wheels is all about - but to me it feels like you have to turn the wheel to get the bike into the corner, once its in no more turning is necessary.

[SyuRi]

Hey sorry, i did copy them abreviated

Just to clarify the question, i meant is it possible just to turn a bike by leaning to one side? Or is it necessary to turn the wheel?

Here they are:

http://thekneeslider.com/archives/2007/10/09/motorcycle-countersteering-and-the-no-bs-bike/

http://www.soundrider.com/archive/safety-skills/nobsbike.htm

[CookingWithGas]

@SyuRi

…is it possible just to turn a bike by leaning to one side? Or is it necessary to turn the wheel?

On a flat surface you can initiate a turn by leaning but the wheel will follow the track of the turn even if you are not consciously turning it. I suppose if the speed and banking is set up in a certain way you can follow a banked turn without turning the wheel, not sure.

[Flander]

The Wiki article on Countersteer has your answer.

@Wikipedia

Countersteering is the name given to the counter-intuitive technique used by cyclists and motorcyclists to turn corners. It is the only way a rider can cause a single-track vehicle to turn

@SyuRi

i meant is it possible just to turn a bike by leaning to one side? Or is it necessary to turn the wheel?

This is also address in the article. Again, from Wiki:

@Wikipedia

The rider can shift his weight of course, but any force used to move one way laterally pushes the bike laterally the opposite direction with equal force. That makes the bike lean (and can affect the steering), but it doesn’t lean the combined center of mass of bike and rider.

Basically, if you just lean without steering, you push the bike off the other way and the net result is no turn.

[Q.E.D]

If you’re asking if you can steer a bike with the handlebars locked in place, the answer is no, you can’t. You can steer a bike by leaning alone–you can do it with no hands on the grips, in fact. But, if the front wheel is locked in place so it can’t turn, only spin, the bike becomes totally unrideable; it needs to be free to move in order to provide stability.

[Rick]

@Flander

Basically, if you just lean without steering, you push the bike off the other way and the net result is no turn.

While I agree with the idea of countersteering, I disagree with this statement.
On my road bicycle If I am riding with hands off the bars (pedaling or coasting, it makes no difference) I can turn some gentle corners via leaning alone. I cannot turn very tightly, but I can turn.

[SyuRi]

Hmm. In the midst of my research i found this article

http://www.straightdope.com/mailbag/mangularmo.html

and this part specifically says you can turn by just leaning (unless im misreading something, which would be probable since i dont speak english perfectly)

So let’s look at that bike. Using your right hand, curl your fingers in the direction the bike wheels are spinning–forward and around. You should find your thumb pointing to the left. OK, now extend your left arm straight out to the left and point your left index finger. This represents the angular momentum vector of your bike wheels. Unfortunately, sticking your arm out like that also throws off your balance. Oh no, you start to tip over to the left! (Go ahead, tilt to the left–you didn’t think you could do physics without waving your arms around, did you?) Notice that your wheels’ angular momentum vector (i.e., your left arm) is no longer pointing directly left, but rather at some angle towards the ground. The angular momentum vector of your wheels has changed, but that’s a problem because angular momentum is conserved. You need to acquire some other component of angular momentum to ensure conservation. To restore the original angular momentum of your untilted bike, you need to add a vector quantity in the “up” direction to your tilted left arm. What does that mean in terms of motion? The Right Hand Rule tells us. Using your right hand, stick your thumb in the upward direction to represent the additional angular momentum you need. Your fingers are curling around to the left. Thus, your bike will turn to the left to conserve angular momentum.

[Santo_Rugger]

@Rick

While I agree with the idea of countersteering, I disagree with this statement.
On my road bicycle If I am riding with hands off the bars (pedaling or coasting, it makes no difference) I can turn some gentle corners via leaning alone. I cannot turn very tightly, but I can turn.

Sorry Rick, you’re usually spot on, but this is incorrect. When you take your hands off the bars and initiate a turn via leaning, the handlebars turn without your input, and the front wheel turns. Do a couple of weaves and watch the handlebars, you’ll see it turning.

The SuperBike School, a performance motorcycle training company, has what they call a “NO BS” bike, where the handlebars are locked into place. There’s a pretty neat video and description here:

http://www.superbikeschool.com/machinery/no-bs-machine.php

@Q.E.D.

<snip>But, if the front wheel is locked in place so it can’t turn, only spin, the bike becomes totally unrideable; it needs to be free to move in order to provide stability.

Unturnable, yes. Unrideable, no. See video in link above.

[Santo_Rugger]

@SyuRi

Hmm. In the midst of my research i found this article

http://www.straightdope.com/mailbag/mangularmo.html

and this part specifically says you can turn by just leaning (unless im misreading something, which would be probable since i dont speak english perfectly)

That’s poorly written. In reality, with no rider input, a bike will try to maintain as upright position as possble, as long as it has positive rake. Rake is defined as the angle the pivot of the forks to where the wheel makes contact, compared to the vertical. While the writer is correct about angular momentum being conserved, the right hand rule is just a nomenclature convention, and the vector she talks about must be conserved. It does not, however, mean that there’s a real force pushing in that direction. In fact, one can do everything with a left hand rule, as long as they’re consistent.

The video on the site above seems not to be working. Try this:

- YouTube

[ZenBeam]

Hmm. In the midst of my research i found this article

http://www.straightdope.com/mailbag/mangularmo.html

and this part specifically says you can turn by just leaning

Karen Lingel is wrong, and said so in a post, or possibly another article, on this board. I’ll see if I can find it.

Sorry Rick, you’re usually spot on, but this is incorrect.

I read Rick’s statement to mean he can turn by leaning without explicitly steering (i.e. riding “no hands”), which is true, not that he can turn with the front wheel held in a fixed, straight direction, which is something different.

[Santo_Rugger]

@ZenBeam

I read Rick’s statement to mean he can turn by leaning without explicitly steering (i.e. riding “no hands”), which is true, not that he can turn with the front wheel held in a fixed, straight direction, which is something different.

This is true, and it’s really an exercise of semantics. The OP’s question was “Do you need to turn the wheel for the bike to turn?”, while I assume the question meant to be asked was “Does the front wheel need to turn for the bike to turn?”

Rick answered the first one, and I was trying to clarify that that answer was misleading.

[Flander]

@Rick

While I agree with the idea of countersteering, I disagree with this statement.
On my road bicycle If I am riding with hands off the bars (pedaling or coasting, it makes no difference) I can turn some gentle corners via leaning alone. I cannot turn very tightly, but I can turn.

Santo Rugger cover it. Your bike still counter-steers in that circumstance because your handle bars aren’t locked.

[ZenBeam]

Here’s Karen’s second take on steering a bicycle: Why is it easier to balance on a moving bike than a non-moving one (revisited)?

Here’s a couple of lucky bonus threads: Why is it easier to balance on a moving bike than a non-moving one? and Steering motorcycles (countersteering)

[Quercus]

To sum up:

1. It is possible to steer a normal bicycle with your hands off the handlebars. Lots of people are good at it.
2. If the handlebars are locked and cannot turn, on a flat surface it is impossible to turn the bicycle. [Or, if the handlebars are locked in a turned position, the bicycle will always turn at the same angle]. Leaning to one side will just make you fall over.

[Bonus, non-OP #3: Karen got it right the second time.]

[AskNott]

I can’t physically test this on today’s wet streets, or with my funny-looking 8-foot long bicycle. I’ll remind you, though, that a leaning bike tire no longer has a symmetrical footprint. I believe it will “nibble” to the side of the lean.

My other point is that show-off riders of bicycles and motorcycles can ride an impressive distance with the front wheel in the air. They keep from falling over sideways by leaning slightly.

[Santo_Rugger]

@AskNott

I can’t physically test this on today’s wet streets, or with my funny-looking 8-foot long bicycle. I’ll remind you, though, that a leaning bike tire no longer has a symmetrical footprint. I believe it will “nibble” to the side of the lean.

My other point is that show-off riders of bicycles and motorcycles can ride an impressive distance with the front wheel in the air. They keep from falling over sideways by leaning slightly.

Please see video link, above.

Also, note when there’s only one tire on the ground, the dynamics are completely different than when two connected articularable wheels are on the ground.

[scr4]

@Santo Rugger

…a bike will try to maintain as upright position as possble, as long as it has positive rake. Rake is defined as the angle the pivot of the forks to where the wheel makes contact, compared to the vertical.

Don’t you mean trail? Rake is defined as the distance between the steering axis and the wheel axle. Trail is the distance between the tire’s contact patch and the steering axis. (See this diagram). Trail depends on rake, head angle and wheel size. In references I’ve read, it’s the trail that has the biggest effect on handling. That is, if two bikes have very different head angles, but the rake is adjusted so that the trail is similar, then handling will be similar.

[Santo_Rugger]

@scr4

Don’t you mean trail? Rake is defined as the distance between the steering axis and the wheel axle. Trail is the distance between the tire’s contact patch and the steering axis. (See this diagram). Trail depends on rake, head angle and wheel size. In references I’ve read, it’s the trail that has the biggest effect on handling. That is, if two bikes have very different head angles, but the rake is adjusted so that the trail is similar, then handling will be similar.

Yes, trail is a more accurate description, but, all other things being equal, a bigger rake angle (fork offset) will give a bigger trail distance. Thanks for reminding me of the difference, though.