Sprinting and going fast

[Citius]

Can you even imagine how much force he is applying to his pedals for the first half dozen pedal strokes?

Let's stop 'imagining'. How much force does he apply to the pedals? I assume from your somewhat arrogant stance that you must know, so tell me the number.

Do you think he squats 227kg (or at least used to) just to push 90kg of force down through the pedals?

Let's get this into perspective. Hoy's squat of 227kg is quite a bit less than the women's world record, which is somewhere closer 400kg. He's not pushing massive weights, and certainly not pushing anything like those a male weightlifter would lift for his class.

As you have been repeatedly told, the only time you will get anywhere close to applying a maximal force on a pedal is at the start of something like a kilo sprint, but as soon as you begin to move, the forces drop right off and the aerobic pathwways take over - for reasons which are well understood in physics (by everyone but you, it seems).

I really don't get why you are trying to make such an irrelevant point, citing examples of how someone trains for a unique and specific track discipline that 99% of people on here will probably never compete in (ie a kilo sprint), when the thread is about riding on the road. Do you understand that this thread is not about track sprinting, or starting a kilo sprint? You are way off topic with this stuff. You are also embarrassing yourself, but I'll humour you for now

 

[PhilDawson8270]

@marzjennings If cyclists exert more force than their bodyweight.

Can you please explain why professional cyclists in the tour de france do NOT exceed their bodyweight? As I have proven this to be the case previously

 

[PhilDawson8270]

@marzjennings to save you looking, I'll even repost it here for you.

From here
In fact, I'll give it a quick go as an example.

Using information from Stage 18 of the 2013 tdf available here http://velonews.competitor.com/2013...sis-stages-18-19-at-the-tour-de-france_296653 with over 4km of climbing on the stage.

Using Normalised power as the power

Power = 314W
Cadence = 82rpm
Crank Length = 172.5mm (No crank length data so we will just use this)

So Power = work/time

314W = work/time

To find the time we know the crank has radius 172.5 so has diameter 345mm Which has circumference pi*d which comes out to 1083.84mm, since this crank length is already an assumption, I'm quite happy to call this 1.1m for simplicity of calculation.

With a cadence of 82rpm it takes 0.73seconds per revolution

Rearrange power = work/time to work = Power*time

work = 314*0.73
= 229.22 Nm of torque

Which is 23.4 kg m Since 1m is quite close to our full revolution, half of that is what is put through 1 pedal.

So the best cyclists in the world, on a stage that involved much climbing were only putting 11.7 Kg through each pedal stroke.

The amount is tiny, in fact, the weight they put on the pedal is less than some bicycles weigh.

As you can clearly see, strength won't be a limiting factor, and squatting really won't help to get up those hills


From here
http://www.pezcyclingnews.com/toolbox/power-output-and-cadence-learning-from-the-pros/#.VazZn9xViko

That source suggests during large climbs, cadence drops to 71rpm and power stays at 311. So I'd expect the "strength" on this to be higher due to same power and lower cadence.

71rpm is 0.84s per revolution

work = 311*0.84 = 261.24 Nm or 13.31 Kg per leg

So it the pros are only using a little extra power to get up the hills, the difference isn't a massive amount.


Find the power and cadence from a track sprinter, and I'll quite happily do the math.

 

[marzjennings]

@marzjennings If cyclists exert more force than their bodyweight.

Can you please explain why professional cyclists in the tour de france do NOT exceed their bodyweight? As I have proven this to be the case previously

This is getting ridiculous and the inaccurate statement I'm addressing is this one...

The amount of force you can put through bicycle pedals is limited to your weight.
Once you put more force on the pedals than your mass, then all you do is stand up. With nothing to push against, you can only push up to your mass.
Weight and strength is important to sprinting on foot, as more strength means you can propel the body harder, or longer, or faster. On a bicycle, you are limited by your mass.

Not how much force is applied on average through a tour or for the duration of a sprint or kilo. Just the simple fact that any rider can at some point can exert a force greater than their mass through a single pedal stroke. And that a rider's mass is not the limiting factor on how much force they can apply to the pedals for either an instantaneous or very short period of time.

I'm starting to worry that you and @Citius aren't able to carry a couple of heavy shopping bags up a flight of stairs and that you think you can out accelerate a pro tracker rider who's lighter than you.

 

[Citius]

Not how much force is applied on average through a tour or for the duration of a sprint or kilo. Just the simple fact that any rider can at some point can exert a force greater than their mass through a single pedal stroke. And that a rider's mass is not the limiting factor on how much force they can apply to the pedals for either an instantaneous or very short period of time.

I'm starting to worry that you and @Citius aren't able to carry a couple of heavy shopping bags up a flight of stairs and that you think you can out accelerate a pro tracker rider who's lighter than you.

Any chance you could answer my question earlier - you know, the one about how much force Hoy is pushing at the start of a kilo? Don't hold back on us now...

I think it's generally accepted that pedal force is not a limiting factor for either sprinting or endurance - but thanks for pointing that out.

 

[marzjennings]

I think it's generally accepted that pedal force is not a limiting factor for either sprinting or endurance - but thanks for pointing that out.

Again, deliberately avoiding the point, but for some it seems the mass of the cyclist is a limiting factor to the amount of force that can be applied at the pedal.

Do you or @PhilDawson8270 still think a cyclist can not apply a force greater than their mass to the pedals?

 

[Citius]

Again, deliberately avoiding the point, but for some it seems the mass of the cyclist is a limiting factor to the amount of force that can be applied at the pedal.

You don't know, do you. Such a shame, because you seemed very certain earlier.

Do you or @PhilDawson8270 still think a cyclist can not apply a force greater than their mass to the pedals?

Well, I expect Phil can answer for himself. But I personally don't, for all the reasons that have been stated. Can you point me to some evidence that shows it is possible. Maybe use Chris Hoy as an example...

You're obviously entitled to your opinions, but I am entitled to ridicule them if you can't support them.

 

[PhilDawson8270]

Please provide, cadence, crank size and power for any rider if your choice.

I supported my argument with data and maths. If you provide me some data from a tech cyclist. I will happily do the math, which will say for certain.

On a leg press machine your back is supported and body movement restricted. Therefore you loft the weight. I can leg press over 250kg and I weigh 85kg.

What do you think would happen if I tried to do that without having your upwards motion restricted? All that would happen is your would stand up.

Please provide any data you can find

 

[Joshua Plumtree]

Isn't every getting a little bogged down in arguments over leg presses and squats and whether you can transfer most of that power through the pedal stroke. Obviously you can't!

But - if I can squat 300kgs compared to the bloke next to me only being able to squat 200, then, If everything else is equal, I'm gonna be producing more power through the pedal stroke for the same level of effort as the guy who can't squat as much. Surely that's the reason track sprinters use weights in the gym, not to be able to replicate their power output per squat, but to produce a higher power output than they would otherwise achieve at a given intensity level.

How any of this is applicable to use road cyclists is a mute point!

 

[marzjennings]

Please provide, cadence, crank size and power for any rider if your choice.

I supported my argument with data and maths. If you provide me some data from a tech cyclist. I will happily do the math, which will say for certain.

On a leg press machine your back is supported and body movement restricted. Therefore you loft the weight. I can leg press over 250kg and I weigh 85kg.

What do you think would happen if I tried to do that without having your upwards motion restricted? All that would happen is your would stand up.

Please provide any data you can find

You really have no idea what your arms are for do you?

OK some numbers, for the average track start lets say 1500 watts for about 4-12 pedals strokes (Hoy had a max around 2400w for the start). Riders cadence is going from 0 to 60 in about 15 strokes, so average about 30rpm. So taking your basic calculation from earlier on we have more than half the cadence and 5 times the power which would equal well over 100kg per leg. But how is that possible?!?!

Again watch and learn...

At start, full weight on the pedals, legs extending and pushing down through the pedal, backside actually dropping and not lifting as the rider pedals. Arms and core acting together to restrict upper body movement.

 

[Citius]

But - if I can squat 300kgs compared to the bloke next to me only being able to squat 200, then, If everything else is equal, I'm gonna be producing more power through the pedal stroke for the same level of effort as the guy who can't squat as much.

No you aren't. This has been discussed many times.

I still don't understand why we are talking about track starts in a thread about going faster on the road.

 

[marzjennings]

No you aren't. This has been discussed many times.

I still don't understand why we are talking about track starts in a thread about going faster on the road.

Because a incorrect comment was made how one's mass limits the amount of force applied to the pedals. The amount of force you can put through bicycle pedals is limited to your weight.

Also, sprinting is sprinting, track or road and both benefit from additional leg strength.

 

[Citius]

Also, sprinting is sprinting, track or road and both benefit from additional leg strength.

No. This is why it is pointless engaging with you, because you just will not understand. Stop dwelling on minute detail and start looking at the bigger picture, because only the bigger picture is actually relevant. Strength (stronger legs) may give you a higher peak power, but average power is what wins races, not peak power. The Australian track team found that out in Beijing 08, because they spent all their time training for peak and came home with nothing. Cavendish is an excellent example of a (road) sprinter with 'rubbish' peak power (his words). At the top of his game, his average was still far higher than those with supposedly 'stronger' legs.

 

[poynedexter]

a fella was out with me today cycling in a small group. we sprinted to some 30mph signs and i smoked him easily. he's much stronger than me and has big legs. he squats and i havent in about a year.

i dont understand why. we'd both done about 70 miles and he had carbon wheels. i had mudguards on and had done a ramp test on friday and a steady 50 miles on saturday. he still has stronger legs though but his bike went slower.

Mmmmm?

 

[T.M.H.N.E.T]

a fella was out with me today cycling in a small group. we sprinted to some 30mph signs and i smoked him easily. he's much stronger than me and has big legs. he squats and i havent in about a year.

i dont understand why. we'd both done about 70 miles and he had carbon wheels. i had mudguards on and had done a ramp test on friday and a steady 50 miles on saturday. he still has stronger legs though but his bike went slower.

Mmmmm?

Because, magic