Are footpegs superior if you don't pedal?

[donn]

The way I see it, a bicycle in motion is always falling. Stability is the ability to recover from the fall, which we do by steering towards the fall to get the wheels under the center of gravity; maneuverability is the ability to increase the fall, by steering away from it, so that we can take a path where the forces of gravity and centripetal acceleration combine at an angle. These actions can in principle be taken effectively with a center of gravity at any height, but as that gets lower we run into human limitations in perception, response time and reaction precision.

That's how I understand bicycling to work at most speeds - but I will say that as I ride down a long hill on one of my wonderful recumbent bicycles, I don't really perceive that process, and rather it seems like there are gyroscopic and whatever other forces in play that might make center of gravity height less significant, or even possibly change the ideal height.

 

[ebike4healthandfitness]

Real frame builders (not ones that are 100% confirmed not to understand the relationship of fork offset, wheel diameter and trail) know that a low bb height increases stability:

https://calfeedesign.com/geometry-of-bike-handling/

Excuse me, up to now weren't you saying low center of gravity increases stability? Now it's bottom bracket?

Lowering the bottom bracket height does lower the center of gravity. In fact, it is the only way to lower center of gravity without changing other variables that affect handling.

Been saying that since page 3 of this thread as shown below:

Excellent low center of mass handling qualities:

[youtube]5UBWTshFEIg[/youtube]

lol.

As far as high vs low center of gravity. Imagine you have a stick with a weight on one end. Imagine balancing that upright on one finger, like most kids do.

Is it going to be easier to balance when the stick is 3 inches tall or 3 feet tall?

A low racer recumbent is a poor example to use because it is not just a lowering of center of gravity but it is a changing of a whole bunch of other variables at the same time as well.

A much better example of lower center of gravity would be to simply lower bottom bracket height but keep all other aspects of geometry and seating position roughly the same.

 

[ebike4healthandfitness]

The way I see it, a bicycle in motion is always falling. Stability is the ability to recover from the fall, which we do by steering towards the fall to get the wheels under the center of gravity;

That is not what stability is. What you are describing is called balance.(See portion I bolded in the quote below from the link. Also notice what the underlined portion in the quote below says. It's only the rest of the world that believes what I am saying is true.)

https://www.pinkbike.com/news/zeps-how-to-body-position-descending-cornering-braking-2016.html


"STABILITY: The ability to resist forces

- The more stable the rider, the 'stronger' they are - they are harder to 'push over.'
- More stability means more resistance to forces from the trail - more like a picnic table, less like a lamp.
- The lower and more centered an object's centre of mass, the more stable it will be.



BALANCE: The movements you make to manage instability

- If a rider were 100% stable they would be balanced - but this never really happens on a bike.
- The less stable the rider the more balancing is required to stay in control.
- Balancing helps riders manage instability, or recover and regain their stability.
- Balancing is easier if a rider has a better range of movement."

 

[donn]

Lowering the bottom bracket height does lower the center of gravity. In fact, it is the only way to lower center of gravity without changing other variables that affect handling.

Rather, you've been discounting any effects of lowering center of gravity, with the limited exception being where that would be achieved by lowering only the bottom bracket.

Let's bring that quote forward to this page, in case you have something to say about it. They're probably confusing stability with balance?

Now balance the hammer in a dynamic situation by placing it on the end of your finger. You will notice that it is easier to balance with the head above the handle. This is not because it is more stable in a static sense, but the dynamic system of you controlling the movement of the point support of the hammer produces what could be perceived as a more stable result. This is because the greater distance between your finger and the centre of mass means that larger movements are required from your hand to regain static stability when the hammer starts to fall. This in turn means that the system is inherently less sensitive to small movements, which makes it easier for us to coordinate iteration towards a stable solution.

 

[ebike4healthandfitness]

Lowering the bottom bracket height does lower the center of gravity. In fact, it is the only way to lower center of gravity without changing other variables that affect handling.

Rather, you've been discounting any effects of lowering center of gravity, with the limited exception being where that would be achieved by lowering only the bottom bracket.

Lowering the bottom bracket is the only way to control variables.

Chalo's idea of replacing the 26" wheels of a beach cruiser with smaller wheels for the purposes of lowering center of gravity was flawed because it not only lowered center of gravity but reduced trail at the same time. By reducing trail he reduced stability at the same time he was increasing stability. This flawed process (i.e. lack of controlling variables) lead him to the flawed conclusion that lowering center of gravity reduces stability.

So yes, a person needs to control variables or else a false conclusion can be reached.

 

[ebike4healthandfitness]

Let's bring that quote forward to this page, in case you have something to say about it. They're probably confusing stability with balance?

Now balance the hammer in a dynamic situation by placing it on the end of your finger. You will notice that it is easier to balance with the head above the handle. This is not because it is more stable in a static sense, but the dynamic system of you controlling the movement of the point support of the hammer produces what could be perceived as a more stable result. This is because the greater distance between your finger and the centre of mass means that larger movements are required from your hand to regain static stability when the hammer starts to fall. This in turn means that the system is inherently less sensitive to small movements, which makes it easier for us to coordinate iteration towards a stable solution.

Yes, that is a description of balance.

A test of stability would be something like stand a hammer handle down and head up on a flat surface vs. stand the same hammer head down and handle up. Then push on the highest part and measure how much force to make it fall to the ground. The configuration that takes the most force to make fall is the most stable.

Of course, there are some variables pertaining to the handle vs. head surface on the table but you get the idea. If those were controlled the result would still be the top heavy one is the easiest to push over.

 

[speedmd]

configuration that takes the most force to make fall is the most stable

A bikes stability while in motion has little to nothing to do with relatively static balancing IMO. The static hammer example here applied to a bike- riders stability to traverse terrain is a bad one and the conclusions drawn are over simplistic and incorrect also when conclusions are drawn to explain what happens when things start moving IMO. Better used possibly if you were trying to explain a unicycle.

Here, we are moving along. Try now to balance that hammer while rolling along at 15 -20 mph and you accelerate -decelerate or change direction. You quickly realize that you run out of range of motion in your limb to move the base of the hammer handle sufficiently enough to compensate for the kinetic energy in the heavy head of the hammer that is way above the resolving point of influence. Suggesting or implying as in the BA statement that the hammer in this situation is more stable is the opposite of what a rider wants here. It will certainly want to continue to go the direction it's going even while you may want to turn or stop. Stability defined in bike riding is much more. It is more of how precisely and accurately it does what its instructed to do with the minimum work from the rider.

 

[ebike4healthandfitness]

configuration that takes the most force to make fall is the most stable

Stability defined in bike riding is much more. It is more of how precisely and accurately it does what its instructed to do with the minimum work from the rider.

A stable bike can take more work from the rider to get it to do something precisely and accurately. For example, a stable bike can be harder to turn than one that is less stable.

So your definition of stability in riding is not right.

The proper definition of stability is the ability to resist forces.

 

[Chalo]

A test of stability would be something like stand a hammer handle down and head up on a flat surface vs. stand the same hammer head down and handle up. Then push on the highest part and measure how much force to make it fall to the ground. The configuration that takes the most force to make fall is the most stable. .

Wow, you deeply misunderstand single track vehicle physics.

Where do you think the push comes from in a single track vehicle, to make it turn, fall, or stay up? It's the surface. This is related to why you've got your concept so turned around.

And yes, hammer head up is much easier to keep balanced when your input comes from the surface, because there's so much less inertia in the part that must swing around to maintain balance.

 

[ebike4healthandfitness]

A test of stability would be something like stand a hammer handle down and head up on a flat surface vs. stand the same hammer head down and handle up. Then push on the highest part and measure how much force to make it fall to the ground. The configuration that takes the most force to make fall is the most stable. .

Wow, you deeply misunderstand single track vehicle physics.

Where do you think the push comes from in a single track vehicle, to make it turn, fall, or stay up? It's the surface.

It can be the wind too.....or another rider hitting you.

LoL, Chalo I must say your writing always gives me a good laugh.

 

[Chalo]

Wow, you deeply misunderstand single track vehicle physics.

Where do you think the push comes from in a single track vehicle, to make it turn, fall, or stay up? It's the surface.

Not always. It can be the wind too.....or another rider hitting you.

And yet the only input you can use to maintain balance comes from the surface. Why would you increase inertia there? Do you think wind will have somehow less effect a the bike that's light at the top and heavy at the bottom?

Go ahead and laugh, but it's the laugh of a fool. Best persist in your folly, because it seems that's all you've got. Try actually building some things.

 

[ebike4healthandfitness]

Wow, you deeply misunderstand single track vehicle physics.

Where do you think the push comes from in a single track vehicle, to make it turn, fall, or stay up? It's the surface.

Not always. It can be the wind too.....or another rider hitting you.

Do you think wind will have somehow less effect a the bike that's light at the top and heavy at the bottom?

Yes, of course!

It's common knowledge that lower center of gravity improves stability in single track vehicles and that is why all the links I have provided say this also.

 

[Chalo]

Stop reading, because your understanding is broken and reading isn't fixing it. Start actually testing things. Maybe that will help you.

 

[ebike4healthandfitness]

Stop reading, because your understanding is broken and reading isn't fixing it. Start actually testing things. Maybe that will help you.

:lol:

 

[Chalo]

It's not the reading material that's wrong. It's you.

 

[ebike4healthandfitness]

It's not the reading material that's wrong. It's you.

You are putting me to sleep again.

I'm tired of your BS.

 

[99t4]

Question "Are footpegs superior if you don't pedal?" has been answered by the OP, two years after he asked it, back on page one, about half way down. Answered, at least to the satisfaction of the OP.

Anything worthwhile in the subsequent 4 pages?

 

[ebike4healthandfitness]

Question "Are footpegs superior if you don't pedal?" has been answered by the OP, two years after he asked it, back on page one, about half way down. Answered, at least to the satisfaction of the OP.

Anything worthwhile in the subsequent 4 pages?

Basically the confusion about stability vs. Balance gets cleared up:

The way I see it, a bicycle in motion is always falling. Stability is the ability to recover from the fall, which we do by steering towards the fall to get the wheels under the center of gravity;

That is not what stability is. What you are describing is called balance.(See portion I bolded in the quote below from the link. Also notice what the underlined portion in the quote below says. It's only the rest of the world that believes what I am saying is true.)

https://www.pinkbike.com/news/zeps-how-to-body-position-descending-cornering-braking-2016.html


"STABILITY: The ability to resist forces

- The more stable the rider, the 'stronger' they are - they are harder to 'push over.'
- More stability means more resistance to forces from the trail - more like a picnic table, less like a lamp.
- The lower and more centered an object's centre of mass, the more stable it will be.



BALANCE: The movements you make to manage instability

- If a rider were 100% stable they would be balanced - but this never really happens on a bike.
- The less stable the rider the more balancing is required to stay in control.
- Balancing helps riders manage instability, or recover and regain their stability.
- Balancing is easier if a rider has a better range of movement."

P.S. Also notice that the link above in addition to the other two I provided below also points out that lower center of gravity improves stability in single track vehicles.

https://calfeedesign.com/geometry-of-bike-handling/

"BB drop seems to have settled at 7 cm for most road bikes. It’s low enough to provide a low center of gravity yet it’s high enough to allow pedaling through corners without scraping a pedal. 8 cm is used by some builders and can feel more stabile. But the rider should use low profile pedals and not very long cranks. Pedaling through corners is riskier with a lower BB drop."

https://thebicycleacademy.org/blogs/news/speed-vs-stability-gcn-at-the-bicycle-academy

"In this comparative example the Trek’s BB sits 8mm lower relative to its axles than the canyon representing a 10.3% change from 70 to 78 mm. This will again contribute to the greater stability reported by Simon riding the bike."

But for some reason one person still wants to deny the information about lower center of gravity improving stability of single track vehicles contained in the links. Something that has been considered common knowledge for a long time. This despite the discovery his own methodology for determining the effect of lowered center of gravity on stability was flawed by his own lack of controlling variables.

 

[99t4]

So what you are saying is that all contributors on this thread agree with your conceptual understanding (of stability vs. Balance?), except for only one person?

 

[ebike4healthandfitness]

So what you are saying is that all contributors on this thread agree with your conceptual understanding (of stability vs. Balance?), except for only one person?

Only one person, Chalo, disagrees that lowered center of gravity improves stability in single track vehicles. This despite his own methodology for determining the effect of lowered center gravity on stability was flawed by his lack of control of variables. Furthermore, He denies the statements provided by the links regarding lowered center of gravity improving stability in single track vehicles. Instead he has been talking in circles hoping nobody notices his intentional ignoring of the truth. If people want to believe in his tall bikes that is fine with me, but if you get in an accident and hurt yourself remember I tried to help and provided numerous forms of evidence.

 

[speedmd]

The proper definition of stability is the ability to resist forces.

Again, much too simplistic IMO. If we were to include riders forces, how would you get the bike to do much of anything. I say we ask Pat what makes a stable ride.

https://www.youtube.com/watch?v=b162D2W2a7g

 

[Chalo]

Only one person, Chalo, disagrees that lowered center of gravity improves stability in single track vehicles. This despite his own methodology for determining the effect of lowered center gravity on stability was flawed by his lack of control of variables.

That wasn't my method. That was my suggestion dumbed down to where you might possibly be able to do it yourself. You should still try it.

 

[ebike4healthandfitness]

The proper definition of stability is the ability to resist forces.

Again, much too simplistic IMO. If we were to include riders forces, how would you get the bike to do much of anything.

No, it's a spot on definition.

A stable bike resists the riders force, but other forces as well. This so that when environmental conditions are bad the rider won't have to add in so many correcting movements.

An unstable bike is the opposite. It doesn't resist the rider's force as much but it also doesn't resist environment forces as much either. So when environmental conditions are bad the rider will have to add in a whole bunch of extra correcting movements.

The net effect is that a stable bike will feel more precise in bad environmental conditions (because of the reduced amount of corrective actions needed). Though in good environmental conditions it will feel heavier to use (e.g. takes more work to do a turn, etc.)

 

[speedmd]

If the bike does not accept commands in a predictable-linier and manageable fashion, it would not be stable to ride over extremely varied terrain. What term comes to mind in the over simplified def could be termed Stubborn - heavy feeling or lacking drivability or maneuverability. Horse heads back to the barn on his own, as the old farmer puts it. He sends ones like them to the glue factory.

 

[BalorNG]

If the bike does not accept commands in a predictable-linier and manageable fashion, it would not be stable to ride over extremely varied terrain. What term comes to mind in the over simplified def could be termed Stubborn - heavy feeling or lacking drivability or maneuverability. Horse heads back to the barn on his own, as the old farmer puts it. He sends ones like them to the glue factory.

*Stability* and *manoeuvrability* are negatively correlated.