First attempt with SPD's today in 30 mins

Aidy

antfly wrote:

Let me guess, you can turn the pedals with two hands easier than one?

Nah, don't be silly. The forces work in opposite directions so it's actually harder to turn the cranks with two hands. Because of gravity.

antfly

Oh bugger. Silly me. :?

supersonic

I've had a rethink, and I think, as before, that we are all sort of right. And wrong.

It comes down to cadence. So far I have been looking at a typical high cadence.

At very low cadence and high gear, you may be able to pull up and apply extra force into the system as the descending pedal is dropping very slowly because of that gear - you are pulling hard against the gear. This is very inefficient, and not many people do it. People have indeed pointed this out earlier.

At typical mid high cadence the effect is vastly reduced, and as most studies show there is still negative torque from the upcoming pedal. You simply cannot match the speed of the other descending pedal that you are pushing down against. In effect you are trying to unweight the pedal, which is simply transferring weight to the other side like many have said and is the scenario I was looking at. It may be a case of how we look at it relatively.

Interestingly, the study I showed that even at low cadence, actively trying to pull up in fact reduced overall torque, even if the absolute value of negative torque was less. And was least mechanically efficient.

stuart_c-2

So, we're overpedaled??

supersonic

I think we are over thinking lol.

Oxygen Thief

That's how I see it just can't get it down in words, your leg is enver goign to be able to pull up at the rate in which your other one is pushing down. It'll feel like the normal feeling using flatss when your in too slack a gear.

Oxygen Thief

If you try stickign teh bike in the hardest gear, clip in then push and pull it will help you.

Try this again in easiest gear, there'll be no difference.

Anonymous

Aidy wrote:

Try this experiment.

Put the bike in a workstand, using one hand spin the pedals.
Get a friend to apply the rear brake to the precise point where you can no longer rotate the pedals.

Now use both hands, one on each pedal.

But in that example, you are braced firmly against the floor. If you were doing handstands with one hand on each pedal, and nothing else supporting your weight, then no, you would not be able to put any more power using two hands than one.

Oxygen Thief

yeehaamcgee wrote:

Aidy wrote:

Try this experiment.

Put the bike in a workstand, using one hand spin the pedals.
Get a friend to apply the rear brake to the precise point where you can no longer rotate the pedals.

Now use both hands, one on each pedal.

But in that example, you are braced firmly against the floor. If you were doing handstands with one hand on each pedal, and nothing else supporting your weight, then no, you would not be able to put any more power using two hands than one.

You've got ot rememebr too though that when unseated your weight travel up and down so there's extra force going down than bodyweight. Just like when your running or if you juimp and hit the floor, the downward force is more than the bodyweight.

Aidy

yeehaamcgee wrote:

Aidy wrote:

Try this experiment.

Put the bike in a workstand, using one hand spin the pedals.
Get a friend to apply the rear brake to the precise point where you can no longer rotate the pedals.

Now use both hands, one on each pedal.

But in that example, you are braced firmly against the floor. If you were doing handstands with one hand on each pedal, and nothing else supporting your weight, then no, you would not be able to put any more power using two hands than one.

The limiting point at where you apply brakes whilst pushing with one hand is directly equivalent to your weight. If you pushed any harder you'd leave the floor.

By pulling the opposing pedal up, you can overcome this limit.

Anonymous

Aidy wrote:

yeehaamcgee wrote:

Aidy wrote:

Try this experiment.

Put the bike in a workstand, using one hand spin the pedals.
Get a friend to apply the rear brake to the precise point where you can no longer rotate the pedals.

Now use both hands, one on each pedal.

But in that example, you are braced firmly against the floor. If you were doing handstands with one hand on each pedal, and nothing else supporting your weight, then no, you would not be able to put any more power using two hands than one.

The limiting point at where you apply brakes whilst pushing with one hand is directly equivalent to your weight. If you pushed any harder you'd leave the floor.

By pulling the opposing pedal up, you can overcome this limit.

Incorrect. By having your feet planted on the floor and turning with your hands, you not only have your weight turning the cranks, you also have the strength in your legs, core, arms and so on, pushing against the floor to assist in turning.
This does not factor when you're supporting your weight on the cranks.

Aidy

yeehaamcgee wrote:

Aidy wrote:

The limiting point at where you apply brakes whilst pushing with one hand is directly equivalent to your weight. If you pushed any harder you'd leave the floor.

By pulling the opposing pedal up, you can overcome this limit.

Incorrect. By having your feet planted on the floor and turning with your hands, you not only have your weight turning the cranks, you also have the strength in your legs, core, arms and so on, pushing against the floor to assist in turning.
This does not factor when you're supporting your weight on the cranks.

Um. Try again.
If you're pushing against the floor to apply force, then you're pushing the pedals up.

In my scenario, you push the leading pedal down with one hand. You can't push harder than your body weight, or you leave the ground.

If you pull up as well, you can overcome this limit.

RealMan

supersonic wrote:

I've had a rethink, and I think, as before, that we are all sort of right. And wrong.

It comes down to cadence. So far I have been looking at a typical high cadence.

At very low cadence and high gear, you may be able to pull up and apply extra force into the system as the descending pedal is dropping very slowly because of that gear - you are pulling hard against the gear. This is very inefficient, and not many people do it. People have indeed pointed this out earlier.

At typical mid high cadence the effect is vastly reduced, and as most studies show there is still negative torque from the upcoming pedal. You simply cannot match the speed of the other descending pedal that you are pushing down against. In effect you are trying to unweight the pedal, which is simply transferring weight to the other side like many have said and is the scenario I was looking at. It may be a case of how we look at it relatively.

Interestingly, the study I showed that even at low cadence, actively trying to pull up in fact reduced overall torque, even if the absolute value of negative torque was less. And was least mechanically efficient.

I think you're close here. Pulling up at a low cadence does give you more power and thus bigger acceleration, but obviously requires more effort so maybe its less efficient.

Generally when you get up to a higher cadence you would be sitting back down, and thus pulling up, you pull against the saddle, and makes your riding more efficient as you are using more muscles.

Oxygen Thief

You can't push down more than your bodyweight no matter what, so even if you pull up with the other foot the leading one still can't push any harder. It'll just get left behind sort of by the leading pedal so the force it's exerting is not as ahrd because teh force pulling up makes up for it and overall force applied will be the same.

Aidy

supersonic wrote:

I've had a rethink, and I think, as before, that we are all sort of right. And wrong.

It comes down to cadence. So far I have been looking at a typical high cadence.

At very low cadence and high gear, you may be able to pull up and apply extra force into the system as the descending pedal is dropping very slowly because of that gear - you are pulling hard against the gear. This is very inefficient, and not many people do it. People have indeed pointed this out earlier.

At typical mid high cadence the effect is vastly reduced, and as most studies show there is still negative torque from the upcoming pedal. You simply cannot match the speed of the other descending pedal that you are pushing down against. In effect you are trying to unweight the pedal, which is simply transferring weight to the other side like many have said and is the scenario I was looking at. It may be a case of how we look at it relatively.

Interestingly, the study I showed that even at low cadence, actively trying to pull up in fact reduced overall torque, even if the absolute value of negative torque was less. And was least mechanically efficient.

Whether it's an efficient use of energy to pull up is a different question entirely.
However, it's entirely possible to apply more power by pulling up with the trailing foot. I really don't understand why people can't see this.

supersonic

Hmm, most studies seem to show that pulling up to be less efficient overall. But also shows that your preferred method is usually the best for an individual out of all methods employed. I guess that is due to the fact that active 'pullers' may have stronger and better developed muscles in that department. This may also explain whey lower torque is generated.

Aidy

jonbonjovial wrote:

You can't push down more than your bodyweight no matter what, so even if you pull up with the other foot the leading one still can't push any harder. It'll just get left behind sort of by the leading pedal so the force it's exerting is not as ahrd because teh force pulling up makes up for it and overall force applied will be the same.

You can push down with more than your body weight if you're braced against something.

Like say, the trailing pedal.

Oxygen Thief

c

supersonic

Aidy wrote:

supersonic wrote:

I've had a rethink, and I think, as before, that we are all sort of right. And wrong.

It comes down to cadence. So far I have been looking at a typical high cadence.

At very low cadence and high gear, you may be able to pull up and apply extra force into the system as the descending pedal is dropping very slowly because of that gear - you are pulling hard against the gear. This is very inefficient, and not many people do it. People have indeed pointed this out earlier.

At typical mid high cadence the effect is vastly reduced, and as most studies show there is still negative torque from the upcoming pedal. You simply cannot match the speed of the other descending pedal that you are pushing down against. In effect you are trying to unweight the pedal, which is simply transferring weight to the other side like many have said and is the scenario I was looking at. It may be a case of how we look at it relatively.

Interestingly, the study I showed that even at low cadence, actively trying to pull up in fact reduced overall torque, even if the absolute value of negative torque was less. And was least mechanically efficient.

Whether it's an efficient use of energy to pull up is a different question entirely.
However, it's entirely possible to apply more power by pulling up with the trailing foot. I really don't understand why people can't see this.

I can see it at high chain tension. But the studies still show a reduction in torque when trying to pull up, or spin circles. Maximum produced torque seems to be always at the power down stroke for the vast majority of people and cadences.

RealMan

Aidy wrote:

jonbonjovial wrote:

You can't push down more than your bodyweight no matter what, so even if you pull up with the other foot the leading one still can't push any harder. It'll just get left behind sort of by the leading pedal so the force it's exerting is not as ahrd because teh force pulling up makes up for it and overall force applied will be the same.

You can push down with more than your body weight if you're braced against something.

Like say, the trailing pedal.

+1, can't believe after 18 pages people still think that.

Oxygen Thief

Aidy wrote:

jonbonjovial wrote:

You can't push down more than your bodyweight no matter what, so even if you pull up with the other foot the leading one still can't push any harder. It'll just get left behind sort of by the leading pedal so the force it's exerting is not as ahrd because teh force pulling up makes up for it and overall force applied will be the same.

You can push down with more than your body weight if you're braced against something.

Like say, the trailing pedal.

But are you braced against it? Any force applied to the trailing pedal in an upwards direction has an equal force in the downwards direction, this force will act out on teh leading pedal pulling it towards the ground. But there'd be no extera power transferred form the leg.

Aidy

jonbonjovial wrote:

But your not braced against it. To be braced against it you'd have to be pushing that trailign pedal down too. if your pulling it up then your not braced against it.

Um, really now?

supersonic

I agree at lower cadences and higher gears you can generate more overall torque than simply your body weight on the pedal. I disagree you can do it at higher cadences. Where it crosses over I do not know.

RealMan

I'm not saying you can generate higher torque. I'm saying because you're using more muscles its more efficient when you're sitting down. Imagine the difference between cycling one legged and two legged. Two legged is obviously less tiring. Because it uses more muscles.

supersonic

But the studies do not show that. They show overall a reduction in efficiency.

Aidy

supersonic wrote:

I agree at lower cadences and higher gears you can generate more overall torque than simply your body weight on the pedal. I disagree you can do it at higher cadences. Where it crosses over I do not know.

That's a limit of the amount of power a person can put out, rather than any kind of mechanical limit.

Oxygen Thief

Why don't they do some tests using a big fuck off metal robot rather than humans. Shouldn't be too hard to do. But don't let Shimano do it ffs.

supersonic

Because humans are fallible - that is worth testing. And maybe the cause of a lot of the reported findings.

RealMan

supersonic wrote:

But the studies do not show that. They show overall a reduction in efficiency.

I dunno I've been doing a study that's gone over a couple of years. I've been the only participant, but I've found it makes it more efficient. So have all the other decent road cyclists I've met.

Aidy

jonbonjovial wrote:

Why don't they do some tests using a big fark off metal robot rather than humans. Shouldn't be too hard to do. But don't let Shimano do it ffs.

'cos it's not hard to deduce given a basic grasp of physics.

(You need to do tests with people still, because people aren't perfect systems ).