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 Post subject: Torque, Cranks and FTP
PostPosted: Thu Jan 20, 2011 10:24 pm 
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Right, excuse me if this is slightly backwards thinking, but I was recently involved in a few discussions that revolved around power output, muscle mass FTP et al.

In these discussions, the conclusion seemed to be that larger riders are capable of higher power outputs not due to muscle mass but a variety of other factors.

So, sorry if that was pointless but, if we start with
Power = Torque x Cadence
then
Power can be increased by increasing either cadence, torque or both
now
From personal experience, increasing cadence tends to rely more heavily on the aerobic systems and torque tends to be more muscular. This leads me to believe that those old arguments for spending time lifting weights might have some validity.

So,
Would improving torque be something to train specifically to help increase power output without extra strain on the cardiovascular system?
Would longer cranks have any benefit (presuming one can overcome the tendency for lower cadences with longer cranks)

Obviously the ideal situation would be to improve torque and cadence and have a monstrous FTP but, I suppose we all have to start somewhere.

Any thoughts?

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PostPosted: Thu Jan 20, 2011 10:33 pm 
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The torque is definitively very important thing when training to become a better cyclists. But firstly, you need to determine either you are a "spinner" or "powerhorse". In other words, you need to find the cadence range, that suits you the best. Then you train power with that cadence range.

This is only my opinion on topic.


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Posted: Thu Jan 20, 2011 10:33 pm 


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PostPosted: Thu Jan 20, 2011 10:40 pm 
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Jurcy wrote:
The torque is definitively very important thing when training to become a better cyclists. But firstly, you need to determine either you are a "spinner" or "powerhorse". In other words, you need to find the cadence range, that suits you the best. Then you train power with that cadence range.

This is only my opinion on topic.


I guess what I'm really saying is that a rider should, in theory, be able to increase their maximum power output by riding slightly longer cranks.

I seem to recall Lance Armstrong rides 175mm cranks which, for being 5'10, is on the long side.

PS - Before anyone jumps at me, I'm fully aware that theory and practice are two completely different things.

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PostPosted: Fri Jan 21, 2011 3:11 am 
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cranks length and power output as been talked about numerous time, its irrelevant.

The more strength from gym work = more torque therefore higher power output argument is quite wrong IMO. What limits your power output is your cardiovascular system and its variety of adaptations, not your strength. The torque requirement (or strength applied to the pedal if you want) is low enough that almost anyone can meet these requirement. You just need to train at higher power output and longer duration to enhance adaptations.

hope it makes sens


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PostPosted: Fri Jan 21, 2011 6:23 am 
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The data on all these subjects seems quite controversial. This is compounded by the fact that there have really been very few rigorous scientific studies, and it is very difficult to define what a "fair" study would be.

So things become dominated by opinion, and there is data that would tend to corroborate just about any opinion.

Personally, I think that there must be an "optimum" crank length that is related to your leg length. But I don't know if being exactly at optimum gives a ......1% boost or a 10% boost.

Similarly, I think leg strength must obviously come into play. But that assumes you have enough cardiovascular power to supply the energy required to USE the extra strength, and over some varying length of time. A 30s sprint ? A 5 min hill jam ?

So you are always limited by the weakest link. Cycling is predominantly a cardiovascular endurance sport, so that is the weakest link for most people.


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PostPosted: Fri Jan 21, 2011 7:58 am 
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I think it's the mitochondria / blood-muscle barrier (terminology escapes me right now) that have the biggest impact. The muscles, no matter how big they are, or how strong, have to do work, which involves oxygen, ATP, ADP, and lactic acid. If you cannot get oxygen to the working muscle, you won't be doing much at all after around 12 seconds.

If weight lifting reduces the mitochondrial density, you will become slower, and perform weaker on the bike, regardless of the weight you can squat or lunge or lift.

No idea on crank length and its impact, other than suggestions that spinning is easier with shorter and grinding / enduro is easier with longer.

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PostPosted: Fri Jan 21, 2011 7:59 am 
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Further to this - when you do weights you might do 4 sets of 25 reps - 100 reps total for the session. That's 1 minute of riding's worth of pedaling at 100 rpm. 1 minute.

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PostPosted: Fri Jan 21, 2011 8:13 am 
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MrAK wrote:
Further to this - when you do weights you might do 4 sets of 25 reps - 100 reps total for the session. That's 1 minute of riding's worth of pedaling at 100 rpm. 1 minute.


I am not really sure about that. The "torque" is much larger in gym that it is on bike. So, IMHO 1 rep = 1 rpm.


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PostPosted: Fri Jan 21, 2011 8:22 am 
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Jurcy wrote:
MrAK wrote:
Further to this - when you do weights you might do 4 sets of 25 reps - 100 reps total for the session. That's 1 minute of riding's worth of pedaling at 100 rpm. 1 minute.


I am not really sure about that. The "torque" is much larger in gym that it is on bike. So, IMHO 1 rep = 1 rpm.


I think you meant 1 rep > 1 rpm, but I agree, torque is higher in the gym. What I am saying is to ride a bike fast the torque is nowhere near as high.

A race of 3km that takes 4 minutes is roughly 400 revs. You could probably generate 4 x times the torque in the gym.

A ride of 5 hours @ 90rpm is 27, 000 revs. I don't think you're doing 270 x times the torque in the gym.

The average race I do is around 2.5 hours - 13, 500 revs @ 90 rpm. Gym may be great for balance, cross-training, strengthening tendons, ligaments and connective tissue, but it's not going to make you a stronger rider (imo) if you are riding that kind of race.

Shorter track events are another matter entirely, but KK is a roadie, not a trackie.

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PostPosted: Fri Jan 21, 2011 9:13 am 
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Just thought I should add a bit to my post.

Let's say, for argument's sake, the maximum power-weight ratio of a pro cyclist is 6.3W. This seems to be an almost universal number. I find this quite hard to believe between all the different body types and sizes out there. With torque being mostly a muscular issue, I can see how training at a higher torque range for longer periods of time could allow one to have higher power outputs than normal. I think my theory applies more to the upper limits of performance, ie. when all the normal avenues of training have been maxed out.

I know cycling is mostly cardiovascular but, any cyclist knows muscular strength does come into play.

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PostPosted: Fri Jan 21, 2011 10:24 am 
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Unfortunately "any cyclist" are quite often misinformed.

I know I can hold 6.4w/kgs but not for very long. Is it because of my strength (when I can deadlift nealy 2x bodyweight)? Or is it another factor, namely those mentioned by MrAK?

Whilst I understand the logic you are trying to apply so far it seems that for just about 99% of the time specificity reigns supreme ie: training in be manner you wish to race.

There are many possible other ways to improve bu so far this one is the most clearly demonstrable in studies.

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PostPosted: Fri Jan 21, 2011 10:51 am 
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kevinkalis wrote:
Just thought I should add a bit to my post.

Let's say, for argument's sake, the maximum power-weight ratio of a pro cyclist is 6.3W. This seems to be an almost universal number. I find this quite hard to believe between all the different body types and sizes out there. With torque being mostly a muscular issue, I can see how training at a higher torque range for longer periods of time could allow one to have higher power outputs than normal. I think my theory applies more to the upper limits of performance, ie. when all the normal avenues of training have been maxed out.

I know cycling is mostly cardiovascular but, any cyclist knows muscular strength does come into play.


I wonder if you perhaps have some interesting ideas or are perhaps not communicating what you really mean?

6.2 W/kg is the max quoted power::weight figure for FTP - "the power sustainable for 1 hour" - not the "maximum power-weight ratio of a pro cyclist". I and many on this board exceed that value when sprinting, Brad McGee et al when pursuiting and the top 10-20 pro cyclists in most prologue stages (<10 minute effort).

I also think you'll find that 6.2W/kg for FTP is not universal - but applies to the top .1% (or less, it's a guesstimate) of pro cyclists. Just count the number of riders finishing first at the top of the big cols in one of the 3 GTs.

If by "muscular strength" you mean "ability to squat a heavy weight" - ie between 1 and 10 reps, then I completely disagree. I can ride rings around other cyclists who can squat significantly more than I can squat. At any distance. My sample includes a quicker flying 200m vs a sprinter who trains specifically for the event, who can squat 205kg vs me not doing squats or any weights at all. The most I have ever squatted is 70kg, but that was years ago. You could almost say muscular strength means diddly squat ;-)

Power is work done. Torque, when discussing power, is irrelevant without taking into account the cadence at which the torque is generated, and you are immediately back to your aerobic capacity for any event longer than 12 seconds, because your muscles cannot do ongoing work without oxygen.

In the context of generating power on the bike, muscular strength is mostly irrelevant.

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PostPosted: Fri Jan 21, 2011 11:10 am 
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MrAK wrote:
6.2 W/kg is the max quoted power::weight figure for FTP - "the power sustainable for 1 hour" - not the "maximum power-weight ratio of a pro cyclist". I and many on this board exceed that value when sprinting, Brad McGee et al when pursuiting and the top 10-20 pro cyclists in most prologue stages (<10 minute effort).


Sorry, I'm coming across in a profoundly retarded way. 6.3W/kg FTP, that's what I meant to say.

I think what I'm getting at is when one gets to the stage where they've pretty much reached their limit for FTP, it would make sense to me to look at different factors to keep improving. Increasing sustainable torque seems an obvious choice to me. Basically, if all other factors remain the same, simply increasing crank length from 172.5 to 175 yields greater torque. Increase the multiplier without decreasing the other factors and you should end up with greater power.

EDIT - Take Mountainbiking for example, although cranksets come in all lengths, the most popular length seems to be 175mm.

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PostPosted: Fri Jan 21, 2011 11:24 am 
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kevinkalis wrote:
MrAK wrote:
6.2 W/kg is the max quoted power::weight figure for FTP - "the power sustainable for 1 hour" - not the "maximum power-weight ratio of a pro cyclist". I and many on this board exceed that value when sprinting, Brad McGee et al when pursuiting and the top 10-20 pro cyclists in most prologue stages (<10 minute effort).


Sorry, I'm coming across in a profoundly retarded way. 6.3W/kg FTP, that's what I meant to say.

I think what I'm getting at is when one gets to the stage where they've pretty much reached their limit for FTP, it would make sense to me to look at different factors to keep improving. Increasing sustainable torque seems an obvious choice to me. Basically, if all other factors remain the same, simply increasing crank length from 172.5 to 175 yields greater torque. Increase the multiplier without decreasing the other factors and you should end up with greater power.

EDIT - Take Mountainbiking for example, although cranksets come in all lengths, the most popular length seems to be 175mm.


MTBers pedal slower, torque goes up, cadence goes down, power is unchanged.

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PostPosted: Fri Jan 21, 2011 11:29 am 
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MrAK wrote:
MTBers pedal slower, torque goes up, cadence goes down, power is unchanged.


OK, fair enough. So would you say one cannot increase torque without cadence dropping? I mean that purely from using longer cranks.

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Posted: Fri Jan 21, 2011 11:29 am 


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