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Please help me understand how stem length affects steering

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Please help me understand how stem length affects steering

Old 06-24-21, 06:19 PM
  #51  
livedarklions
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Originally Posted by terrymorse View Post
Have you negotiated a twisting road without using your hands to steer? I know people who can do it, but they are rare. Maybe livedarklions is one of them.

Based solely on my observation of a few thousand riders over 20 years or so, most people steer with their hands, most of the time.
And I'd say you really can't observe whether their hands are merely adjusting the bars to maintain balance while leaning or initiating the turn with their hands. Your assertion is that countersteering is the predominant method of turning, that isn't synonomous with the hands play some role in turning. Humans are not conscious of most of the thousands of microadjustments they make per minute whenever they're locomoting or even just standing. You're just assuming the hand microadjustments are countersteers.

FWIW, I was once quite adept at riding miles no hands, but alas, that is one skill that did not age well.
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Old 06-24-21, 09:26 PM
  #52  
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Originally Posted by terrymorse View Post
Countersteering with the handlebars isn't merely possible on a bicycle. It is the predominant method for steering and balancing a bicycle.

Steering by shifting body weight is certainly possible on a bike, but seldom do people actually perform it (unless their hands are not on the bars), and most of those who say they steer with their bodies are actually handlebar steering but don't realize they are.

Except at slow speeds, handlebar steering inputs are tiny. That is why people don't notice they are doing them.
Right. Moving the bars by hand can overpower any body weight shifting, while the reverse is not true. You'd think someone who can't ride for miles without hands on bars would get this.
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Old 06-24-21, 09:38 PM
  #53  
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Originally Posted by DaveSSS View Post
Bicycles steer in the same manner as a motorcycle, but the force required to turn a bicycle is small compared to a motorcycle. Those who have never taken a motorcycle training course should try it. After completing the motorcycle training, you can apply it to your bicycle. One of the first things you'll discover is that the countersteering force does not just initiate a turn. If you ever let up on the pushing force required to turn, the bike or motorcycle will quit turning. A if that were not true, how would you change the turn radius? The answer is that you push harder to turn sharper or push with less force widen the turn. Speed changes also affect the turn radius. Slower speed tightens the turn. Faster widens the turn. Most single vehicle motorcycle wrecks occur when the rider fails to understand or apply these basic principles. Anyone who says that countersteering only initiates a turn is clueless.
You're confusing counter steering (briefly turning the bars opposite the direction you want to turn) with applying pressure to prevent the bars from returning to straight ahead position once in a turn. When you're doing the latter as you explained, that is not counter steering. The bars are still pointing the same direction you are turning (not counter) even though you need to use force to keep them there.
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Old 06-24-21, 10:33 PM
  #54  
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Originally Posted by DaveSSS View Post
Anyone who says that countersteering only initiates a turn is clueless.
Originally Posted by AlmostTrick View Post
You're confusing counter steering (briefly turning the bars opposite the direction you want to turn) with applying pressure to prevent the bars from returning to straight ahead position once in a turn. When you're doing the latter as you explained, that is not counter steering. The bars are still pointing the same direction you are turning (not counter) even though you need to use force to keep them there.
Maybe DaveSSS meant that the countersteering is also used to exit the turn? This is true. This article explains it though, no need to take a motorcycle class: https://www.adventurecycling.org/def...ring_Heine.pdf
Also the video here: https://www.renehersecycles.com/myth...untersteering/

Another note: countersteering is initiated by a wheel turn, which in its turn is initiated by turning the bars or leaning -- does not matter.
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Old 06-25-21, 05:25 AM
  #55  
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Originally Posted by csport View Post
Maybe DaveSSS meant that the countersteering is also used to exit the turn? This is true. This article explains it though, no need to take a motorcycle class: https://www.adventurecycling.org/def...ring_Heine.pdf
Also the video here: https://www.renehersecycles.com/myth...untersteering/

Another note: countersteering is initiated by a wheel turn, which in its turn is initiated by turning the bars or leaning -- does not matter.

That article can't be correct, if it were, no one could turn no-handed or steer a unicycle. It states a bunch of stuff that makes that possible is impossible. All due respect to the author, but that's reason enough for me to reject everything that follows from those assertions.


Sometimes the easiest way to understand the importance of something is to "break" it. I recently rode with an unbalanced load on my rear rack. You become very aware of how much lean initiates a turn when you have to do it differently than normal.


No one's arguing hands play no role, I just find all this "this is how everyone steers" stuff simplistic, and based on assertions that are obviously over-broad. If I'm initiating my turns with a countersteer, I have yet been unable to detect it. I'm not finding these "you must be" assertions to be based on anything other than the axiomatic assertions of people who have been trained in a particular technique. I'm also aware that I perform different kinds of turns in drastically different ways.

People are sitting differently on the bike, using completely different styles of handlebars and frames, riding at all sorts of different speeds, on all kinds of different surfaces, with drastically different tire widths, and with different attitudes towards maintaining speed through the turn. Any assumption that they are all employing the same turn technique for every turn is just implausible.

Getting back to the topic of the OP, obviously stem length and handlebar width affect the effort needed to turn the wheel, but the effects on posture also affect distribution of your body weight.

Last edited by livedarklions; 06-25-21 at 06:56 AM.
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Old 06-25-21, 06:18 AM
  #56  
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Originally Posted by AlmostTrick View Post
You're confusing counter steering (briefly turning the bars opposite the direction you want to turn) with applying pressure to prevent the bars from returning to straight ahead position once in a turn. When you're doing the latter as you explained, that is not counter steering. The bars are still pointing the same direction you are turning (not counter) even though you need to use force to keep them there.
That could be true, but the pressure against the bars in the opposite direction that you're turning must be maintained or the bike will straighten up. The direction that the wheel is turned is irrelevant. I was taught to look ahead at where I want the bike to go, not look at the front tire. As far as I'm concerned, pushing continuously on the right side to turn right is still is counter steering.
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Old 06-25-21, 06:46 AM
  #57  
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Originally Posted by DaveSSS View Post
That could be true, but the pressure against the bars in the opposite direction that you're turning must be maintained or the bike will straighten up. The direction that the wheel is turned is irrelevant. I was taught to look ahead at where I want the bike to go, not look at the front tire. As far as I'm concerned, pushing continuously on the right side to turn right is still is counter steering.

Yeah, no. As far as I can tell, the wheel turns in the direction of the turn and lean to maintain the turn. To the extent I'm using counter-pressure on the handlebars, I'm doing it to prevent the wheel turn from being too extreme and/or forcing it out of the turn. This is not countersteering, it's course correction. I'm either regulating the extent of the lean, or I am actually actively ending it, not doing anything to extend it.
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Old 06-25-21, 06:58 AM
  #58  
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Originally Posted by livedarklions View Post
Yeah, no. As far as I can tell, the wheel turns in the direction of the turn and lean to maintain the turn. To the extent I'm using counter-pressure on the handlebars, I'm doing it to prevent the wheel turn from being too extreme and/or forcing it out of the turn. This is not countersteering, it's course correction. I'm either regulating the extent of the lean, or I am actually actively ending it, not doing anything to extend it.
The effect of countersteering is easy to see in Keith Code's videos with the motorcyle fitted with a fixed bar. it is impossible to turn the motorcycle more than a few degrees off center by the rider leaning. This would be easy enough to verify on your bicycle. Weld or otherwise lock your headset to not allow turning of the bar/fork. Then you can lean all you like to test out the theory. Please report the results back here.

Riding with no hands, bicycle or motorcycle, is not an issue, including turning to follow the roadway or even do stunts-- but your weight shifts are actually inducing countersteering.
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Old 06-25-21, 07:35 AM
  #59  
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Originally Posted by redcon1 View Post
The effect of countersteering is easy to see in Keith Code's videos with the motorcyle fitted with a fixed bar. it is impossible to turn the motorcycle more than a few degrees off center by the rider leaning. This would be easy enough to verify on your bicycle. Weld or otherwise lock your headset to not allow turning of the bar/fork. Then you can lean all you like to test out the theory. Please report the results back here.

Riding with no hands, bicycle or motorcycle, is not an issue, including turning to follow the roadway or even do stunts-- but your weight shifts are actually inducing countersteering.

So, the need for a movable steerer=countersteering is the method in which it is employed? That's a complete non sequitur.


When I lean into a turn, my wheel turns into the direction of the lean, not against it. That's not evidence of countersteering, just steering into a turn.

Weight shifts initiate countersteering is a contradiction in terms, btw, so your last statement is total nonsense.

Yes, handlebars play a role in steering, nobody is stupid enough to assert otherwise. The question is whether countersteering is what they're used for.. And if it is, what exactly does that mean for stem length, which is the topic of the thread.

Motorcycles have absolutely no relevance here, btw. Weight, speed, position and motion of the riders are completely different from bicycles. I'm not watching any video on how to turn a motorcycle because I have no reason to care.

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Old 06-25-21, 07:52 AM
  #60  
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The non movable steerer shows that bar position is the main tool for turning, or even just maintaining balancing. That's why you can lean all you want on the bike, or have an unbalanced load, and still go where you want to go by moving the bars. Lock the bars and all the leaning in the world won't get you far. Bar position is a must. Leaning is not.
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Old 06-25-21, 08:12 AM
  #61  
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Originally Posted by livedarklions View Post
So, the need for a movable steerer=countersteering is the method in which it is employed? That's a complete non sequitur.


When I lean into a turn, my wheel turns into the direction of the lean, not against it. That's not evidence of countersteering, just steering into a turn.

Weight shifts initiate countersteering is a contradiction in terms, btw, so your last statement is total nonsense.

Yes, handlebars play a role in steering, nobody is stupid enough to assert otherwise. The question is whether countersteering is what they're used for.. And if it is, what exactly does that mean for stem length, which is the topic of the thread.

Motorcycles have absolutely no relevance here, btw. Weight, speed, position and motion of the riders are completely different from bicycles. I'm not watching any video on how to turn a motorcycle because I have no reason to care.
Patiently waiting for you to complete the experiment I described and report back results. Until then, I suggest you study the others who have actually researched the topic-- and please report back here. The motorcycle studies by Code or others are relevant only that they have similar physical properties to a bicycle-- i.e. 2 wheels and a moveable steering mechanism. Your opinion and experience have little relevance to the actual physics/dynamics of bicycle steering and handling.... and are total nonsense.
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Old 06-25-21, 08:41 AM
  #62  
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Originally Posted by AlmostTrick View Post
The non movable steerer shows that bar position is the main tool for turning, or even just maintaining balancing. That's why you can lean all you want on the bike, or have an unbalanced load, and still go where you want to go by moving the bars. Lock the bars and all the leaning in the world won't get you far. Bar position is a must. Leaning is not.
Originally Posted by redcon1 View Post
Patiently waiting for you to complete the experiment I described and report back results. Until then, I suggest you study the others who have actually researched the topic-- and please report back here. The motorcycle studies by Code or others are relevant only that they have similar physical properties to a bicycle-- i.e. 2 wheels and a moveable steering mechanism. Your opinion and experience have little relevance to the actual physics/dynamics of bicycle steering and handling.... and are total nonsense.
You're both committing the same logical fallacy. You're drawing too much of a conclusion from a very limited experiment.

It actually doesn't demonstrate that leaning is less important than the moveable wheel. All it demonstrates is that there is an interaction between the two variables (weight shifting and a movable wheel) necessary to complete and control turns, and that one variable is easy to eliminate experimentally by locking the wheel. .If you can design an experiment where you can "lock" the rider of a two-wheeled vehicle into an upright position and successfully negotiate turns while in motion, then you could support your statements here.

Riding with an unbalanced load definitely required me to adjust my body position while riding and turning. In that case, I also had to exercise counterforce on the handlebars to limit the lean when I turned towards the heavy side of the bike. That's the opposite of countersteering, where supposedly the counterforce is needed to increase the lean.
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Old 06-25-21, 08:46 AM
  #63  
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Ok, time to freshen this up a bit. Please add countersteering vs stem length into the mix, with bar end shifters and, no bell, no mirrors, but a Garmin computer on an “out front” mount. Socks are rider’s choice. Go!

Never mind. I just noticed that I was too late- that particular idiocy is already being addressed. Well done, Bike Forums, well done! I’m going for a ride…

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Old 06-25-21, 10:33 AM
  #64  
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Originally Posted by AlmostTrick View Post
The non movable steerer shows that bar position is the main tool for turning, or even just maintaining balancing. That's why you can lean all you want on the bike, or have an unbalanced load, and still go where you want to go by moving the bars. Lock the bars and all the leaning in the world won't get you far. Bar position is a must. Leaning is not.
On a motorcycle, yes.
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Old 06-25-21, 10:44 AM
  #65  
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Originally Posted by AlmostTrick View Post
The non movable steerer shows that bar position is the main tool for turning, or even just maintaining balancing. That's why you can lean all you want on the bike, or have an unbalanced load, and still go where you want to go by moving the bars. Lock the bars and all the leaning in the world won't get you far. Bar position is a must. Leaning is not.


It actually doesn't demonstrate that. All it demonstrates is that there is an interaction between the two variables (weight shifting and a movable wheel) necessary to complete and control turns, and that one variable is easy to eliminate experimentally by locking the wheel. .If you can design an experiment where you can "lock" the rider of a two-wheeled vehicle into an upright position and successfully negotiate turns while in motion, then you could support your statements here.

Riding with an unbalanced load definitely required me to adjust my body position while riding and turning. In that case, I also had to exercise counterforce on the handlebars to limit the lean when I turned towards the heavy side of the bike.
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Old 06-25-21, 10:47 AM
  #66  
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Those of you who are skillful enough to be able to walk next to your bike and steer it by holding the saddle can easily demonstrate that countersteering is unnecessary. Lean the bike to the left, and the bike turns to the left. Lean it to the right, and it turns right.

You can, of course, countersteer from the saddle (leaning the bike to the right, say, to begin a left turn), but then you'd be required to jerk the saddle over to heave the bars back in the direction in which they should have been pointed in the first place.

I imagine that there will be no more posts on the subject.
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Old 06-25-21, 10:57 AM
  #67  
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Originally Posted by livedarklions View Post
Yeah, no. As far as I can tell, the wheel turns in the direction of the turn and lean to maintain the turn. To the extent I'm using counter-pressure on the handlebars, I'm doing it to prevent the wheel turn from being too extreme and/or forcing it out of the turn. This is not countersteering, it's course correction. I'm either regulating the extent of the lean, or I am actually actively ending it, not doing anything to extend it.
That may be the way it feels to you on a bicycle, but get on a motorcycle and you'll quickly figure out that constant steering input is needed to keep turning. The only thing that varies is the amount of pressure applied. To quit turning, just quit pushing.
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Old 06-25-21, 11:02 AM
  #68  
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How many of you professing your knowledge of steering have logged thousands of miles on twisting mountain roads on both bicycle and motorcycle? I logged over 10,000 and never missed a turn yet. I think I have it figured out.


I've never used any body English to steer either one. When people start mentioning something other than leaning along with the bike and mention the saddle being involved, I know you're clueless.

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Old 06-25-21, 11:06 AM
  #69  
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Originally Posted by DaveSSS View Post
How many of you professing your knowledge of steering have logged thousands of miles on twisting mountain roads on both bicycle and motorcycle? I logged over 10,000 and never missed a turn yet. I think I have it figured out.
0 miles on motorcycles, 10s of thousands of hilly curvy on bicycle. Not exactly flopping around, either. I think you've figured out whhat works for you and have just assumed it's true for everyone else.
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Old 06-25-21, 11:11 AM
  #70  
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Originally Posted by DaveSSS View Post
That may be the way it feels to you on a bicycle, but get on a motorcycle and you'll quickly figure out that constant steering input is needed to keep turning. The only thing that varies is the amount of pressure applied. To quit turning, just quit pushing.
SO you admit that the motorcycle feels different from the bicycle? Maybe that's because they ARE different.

Let's see, tire width, weight, speed, driver--largely static vs. rider constantly pedaling, position on the vehicle, none of those differences are relevant to you?

This is completely off the OP's topic. I'm out at this point.
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Old 06-25-21, 11:35 AM
  #71  
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The principles that affect bicycle and motorcycle steering are the same, but obviously even a small motorcycle is very heavy and the steering input required is much larger. I've practiced negotiating tight turns on a descent with my bicycle, using exactly the same technique I was taught in my motorcycle training course. A tight turn can be negotiated with only one hand in an open position allowing only a push on the proper side. Push more to tighten the turn or let off a little to widen it. Same thing with a motorcycle. It's very simple.
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Old 06-25-21, 11:51 AM
  #72  
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Originally Posted by Trakhak View Post
You can, of course, countersteer from the saddle (leaning the bike to the right, say, to begin a left turn), but then you'd be required to jerk the saddle over to heave the bars back in the direction in which they should have been pointed in the first place.
But while not obvious, that is the way leaning works to steer a bike.

If you're balanced and going straight on a bike, you can't simply lean your body to the left without having the bike simultaneously lean to the right.

Here's the sequence:

0. bike+rider balanced going straight
1. rider leans torso to left
2. bike leans to right
3. bike steers to right, contact patch moves right
4. bike leans to left
5. bike steers to left
6. bike+rider now balanced in left turn

To those who say "but I can lean one way without having the bike lean the other way". Freshman physics says "no, you can't".

Originally Posted by Trakhak View Post
I imagine that there will be no more posts on the subject.
That's hilarious!
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Old 06-25-21, 12:36 PM
  #73  
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Originally Posted by livedarklions View Post
0 miles on motorcycles, 10s of thousands of hilly curvy on bicycle. Not exactly flopping around, either. I think you've figured out whhat works for you and have just assumed it's true for everyone else.
Just as I suspected. No other 2-wheeled experience except on a bicycle, and cannot draw the parallels because you've never experienced them-- and your mind is closed to the physics.
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Old 06-25-21, 02:57 PM
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Old 06-25-21, 11:23 PM
  #75  
csport
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Originally Posted by livedarklions View Post
That article can't be correct, if it were, no one could turn no-handed or steer a unicycle. It states a bunch of stuff that makes that possible is impossible. All due respect to the author, but that's reason enough for me to reject everything that follows from those assertions.

Sometimes the easiest way to understand the importance of something is to "break" it. I recently rode with an unbalanced load on my rear rack. You become very aware of how much lean initiates a turn when you have to do it differently than normal.

No one's arguing hands play no role, I just find all this "this is how everyone steers" stuff simplistic, and based on assertions that are obviously over-broad. If I'm initiating my turns with a countersteer, I have yet been unable to detect it. I'm not finding these "you must be" assertions to be based on anything other than the axiomatic assertions of people who have been trained in a particular technique. I'm also aware that I perform different kinds of turns in drastically different ways.

People are sitting differently on the bike, using completely different styles of handlebars and frames, riding at all sorts of different speeds, on all kinds of different surfaces, with drastically different tire widths, and with different attitudes towards maintaining speed through the turn. Any assumption that they are all employing the same turn technique for every turn is just implausible.

Getting back to the topic of the OP, obviously stem length and handlebar width affect the effort needed to turn the wheel, but the effects on posture also affect distribution of your body weight.
Yes, frame geometry and the rider posture have their effect on the bike handling. But the base mechanism is the same.

Unicycle is a good question, we will need to do some research to find out.

Originally Posted by Trakhak View Post
Those of you who are skillful enough to be able to walk next to your bike and steer it by holding the saddle can easily demonstrate that countersteering is unnecessary. Lean the bike to the left, and the bike turns to the left. Lean it to the right, and it turns right.
This is a different setup as your feet are touching the ground, and additional (as opposed to wheels only) forces/torques are applied via the feet.

Originally Posted by terrymorse View Post
But while not obvious, that is the way leaning works to steer a bike.
If you're balanced and going straight on a bike, you can't simply lean your body to the left without having the bike simultaneously lean to the right.
Here's the sequence:
0. bike+rider balanced going straight
1. rider leans torso to left
2. bike leans to right
3. bike steers to right, contact patch moves right
4. bike leans to left
5. bike steers to left
6. bike+rider now balanced in left turn
To those who say "but I can lean one way without having the bike lean the other way". Freshman physics says "no, you can't".
Exactly. And if we assume that the wheel in step 3 turns under the weight of the wheel + fork + handlebars, the responsiveness of this turn depends on the front geometry. Does it explain why the rando bikes need front load to handle better?

Coming back to that v^2/r formula, at large speed a small turn of the front wheel has larger effect, and it can easily lead to a fall. There is a video by GCN saying that responsive steering is desirable at a small speed and less responsive steering is desirable at a large speed:
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