Pushing down harder vs. perfect circle, and power cranks

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Pushing down harder vs. perfect circle, and power cranks

Postby twizzle » Tue Nov 17, 2009 9:54 pm

There doesn't seem to have been much science discussed in previous posts on pedalling, so I though I would pose some questions. I'm thinking about this in the context of crits., where I always seem to get jumped just after a short sprint effort and the legs are temporarily burnt out.

But first, some background and thinking material.

- Cadel is a P C user and credits the P C's with better performance (it's in his book... yes, I bought it).
- Pro rider spotted in QLD riding 60+km distances one-legged by an elite triathlete I was talking to recently.
- Single leg efforts appearing in just about every training manual on the market.
- This abstract from a study which shows that mechanical efficiency is approx. 9% less when 'pulling up' (or lifting the leg up so the pedal isn't loaded?) as well as pushing, but the elite cyclists had an 86% increase in pedalling 'effectiveness' (power?).
- New.This abstract which says that circle pedalling is as efficient as 'preferred' pedalling, and efficiency only drops when 'pulling' on the pedals.
- This article which reckons some pro's have crap VO2max, but awesome efficiency.
- The other day when riding up a (short) hill and switching from 'push harder on the pedals' to 'turn circles' gave me a power output jump from 350W up to around 500W and it felt bloody easy... although if I was going up a hill for long enough I'm sure I'd see it in the heart rate pretty quickly.
- Looking at the (limited) power/hr data, my HR seemed to rise more slowly when doing the 'perfect circle' stuff vs. similar power levels when mashing the pedals. But I need to do some more testing when I'm not sick. :evil:

Q: In the context of pro riders, what constitutes 'efficiency' in pedalling effort?
Q: Does the recruitment of more muscles when 'turning circles' mean that the lactic acid is less concentrated, and recovery will be quicker?
Q: What training techniques are there for improving mechanical efficiency in pedalling effort?

edit: another article linked in.
Last edited by twizzle on Wed Nov 18, 2009 1:48 pm, edited 1 time in total.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Ant. » Wed Nov 18, 2009 12:07 am

Evans is a circler because he was a mountain biker for an incredible amount of time prior to turning to the road. They pedal circles for traction (heavy downstroke following a "dead spot" could cause rear tyre spinning), so it's probably an ingrained habit. No doubt, for some road cyclists, it's a learned habit though, for better or for worse.

I think it's all about oxygen delivery, which is the limiter. Recruit more muscles if you so wish but in reality, you only have the same blood supply as before, so it's just spreading thinner, so to speak.
Try doing a 20min interval pedalling circles :lol: you'll be chewing on your stem after 5mins.

I don't care about every training book out there, I only care about my coaching, and I've yet to see any single leg exercises out there.... pretty sure it's not hurting my cause, eh?
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby tripstobaltimore » Wed Nov 18, 2009 8:15 am

twizzle wrote:- The other day when riding up a (short) hill and switching from 'push harder on the pedals' to 'turn circles' gave me a power output jump from 350W up to around 500W and it felt bloody easy... although if I was going up a hill for long enough I'm sure I'd see it in the heart rate pretty quickly.


I think this could be attributed to switching the group of muscles employed in the pedal stroke. You would change the group slightly, utilising fresher muscles. I have noticed it too, and thats what my guess as to what it would be.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby bongo » Wed Nov 18, 2009 8:45 am

Ant. wrote:Evans is a circler because he was a mountain biker for an incredible amount of time prior to turning to the road. They pedal circles for traction (heavy downstroke following a "dead spot" could cause rear tyre spinning), so it's probably an ingrained habit. No doubt, for some road cyclists, it's a learned habit though, for better or for worse.

I think it's all about oxygen delivery, which is the limiter. Recruit more muscles if you so wish but in reality, you only have the same blood supply as before, so it's just spreading thinner, so to speak.
Try doing a 20min interval pedalling circles :lol: you'll be chewing on your stem after 5mins.

I don't care about every training book out there, I only care about my coaching, and I've yet to see any single leg exercises out there.... pretty sure it's not hurting my cause, eh?


Chewing your stem is a great analogy for feeling some pain.Like it
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby sogood » Wed Nov 18, 2009 9:03 am

Ant. wrote:Try doing a 20min interval pedalling circles :lol: you'll be chewing on your stem after 5mins.

What flavoured stem do you recommend to keep one going for the next 15? :mrgreen:

In the meantime, waiting for Alex to drop in... Image
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby lemmiwinks » Wed Nov 18, 2009 10:20 am

tripstobaltimore wrote:
twizzle wrote:- The other day when riding up a (short) hill and switching from 'push harder on the pedals' to 'turn circles' gave me a power output jump from 350W up to around 500W and it felt bloody easy... although if I was going up a hill for long enough I'm sure I'd see it in the heart rate pretty quickly.


I think this could be attributed to switching the group of muscles employed in the pedal stroke. You would change the group slightly, utilising fresher muscles. I have noticed it too, and thats what my guess as to what it would be.


Same here. The feeling never lasts for long though.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Wayfarer » Fri Nov 20, 2009 6:44 pm

tripstobaltimore wrote:
twizzle wrote:- The other day when riding up a (short) hill and switching from 'push harder on the pedals' to 'turn circles' gave me a power output jump from 350W up to around 500W and it felt bloody easy... although if I was going up a hill for long enough I'm sure I'd see it in the heart rate pretty quickly.


I think this could be attributed to switching the group of muscles employed in the pedal stroke. You would change the group slightly, utilising fresher muscles. I have noticed it too, and thats what my guess as to what it would be.

i remember when i first started, i had th habit of pushing down on the pedal. as time went on, i moved to cages, and felt a strong power increase. by pushing forward and down on the first quarter, then backwards and down on the second quarter, then pulling back a tad, i definately got an incerase in power. once i shifted to clipless pedals, the power was increased yet again.

i was reading the sports medicine textbook which is a prerequisite for my course, and it was talking about how it can be used to keep the core stable, and although less power is transfered on the upstroke compared with every other stroke, 2-5% more power is gonna make the difference between winning and being the first loser :)
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Nobody » Fri Nov 20, 2009 9:19 pm

sogood wrote:In the meantime, waiting for Alex to drop in... Image
Since Alex is likely tired of repeating himself I'll add something he has posted before:
Image
http://isbweb.org/data/kautz/index.html

I also noticed a change on the trainer when I try to deliberately spin more, but it doesn't last long for me either.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby puffdaddy » Sat Nov 21, 2009 7:36 am

Very interesting,I was told to lift the leg on the upstroke not just unload it,After 4hrs spending most of the time on the aero bars It was not possible,My h/rate was not happy,I was stuffed,Lifting the leg works well with an open hip angle,,,eg: When standing riding a bmx or when standing on your roadie at a very low cadence when topping rolling hills etc,I am no pro racer but like endurance rides and agree totally with this link,,
http://www.ehow.com/way_5300277_road-bi ... nique.html
As for lactic acid,,,burn baby burn :P
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby puffdaddy » Sat Nov 21, 2009 7:58 am

Experiment on your spin trainer,note cadence,h/rate,kph,and perceived effort,Cadence is a real factor here but lets not go down that rd we are all different ,,Like this ,,
http://www.youtube.com/watch?v=Z19zFlPah-o
awsm :o
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby twizzle » Sat Nov 21, 2009 1:04 pm

Nobody wrote:
sogood wrote:In the meantime, waiting for Alex to drop in... Image
Since Alex is likely tired of repeating himself I'll add something he has posted before:

http://isbweb.org/data/kautz/index.html


And what does that chart (and the site) tell us? Anything useful in real-world terms?
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby twizzle » Sat Nov 21, 2009 1:05 pm

puffdaddy wrote:Very interesting,I was told to lift the leg on the upstroke not just unload it,After 4hrs spending most of the time on the aero bars It was not possible,My h/rate was not happy,I was stuffed,Lifting the leg works well with an open hip angle,,,eg: When standing riding a bmx or when standing on your roadie at a very low cadence when topping rolling hills etc,I am no pro racer but like endurance rides and agree totally with this link,,
http://www.ehow.com/way_5300277_road-bi ... nique.html
As for lactic acid,,,burn baby burn :P
Mike :wink:


Pulling up is not recommended according to the study linked in the first post - kills efficiency (in terms of oxygen consumption vs. power).
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Nobody » Sat Nov 21, 2009 7:52 pm

twizzle wrote:
Nobody wrote:
sogood wrote:In the meantime, waiting for Alex to drop in... Image
Since Alex is likely tired of repeating himself I'll add something he has posted before:

http://isbweb.org/data/kautz/index.html


And what does that chart (and the site) tell us? Anything useful in real-world terms?
For a good explanation see Alex. I think he said that there was not much pulling up on the pedals going on.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby toolonglegs » Sat Nov 21, 2009 9:57 pm

Instead of powercranks...buy a mtb and ride in sandy conditions.You need a good rotation there and you will learn some good handling skills while having loads of fun.Whether it improves your road riding I wouldn't know...but you will throw your road bike round a lot better!.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Alex Simmons/RST » Sun Nov 22, 2009 10:42 am

twizzle wrote:Q: In the context of pro riders, what constitutes 'efficiency' in pedalling effort?
The same as for any rider.
Gross Metabolic Efficiency is simply the proportion of mechanical work done to total energy metabolised.

twizzle wrote:Q: Does the recruitment of more muscles when 'turning circles' mean that the lactic acid is less concentrated, and recovery will be quicker?
I can't say for sure but I very much doubt it. I think it could even go the other way, recruiting muscles that aren't adapted to the task will probably add to the problem more quickly.

twizzle wrote:Q: What training techniques are there for improving mechanical efficiency in pedalling effort?
Ride about 10 grand tours and all the training required to be able to do that, or massive volumes at relatively high power outputs (not recovery tooling about).

Efficiency is essentially an inherit trait. There is not a lot of evidence to suggest we can alter it in trained cyclists. It varies of course in an acute sense (temperature, fatigue, cadence etc all have localised or acute impacts on efficiency), but not in a chronic sense.

There is (reasonable) speculation that one of the reasons efficiency may go up through massive volumes is the gradual conversion of some fast/moderate twitch fibres to slow twitch, which are by their nature more efficient. But the evidence is thin as such longitudinal studies (e.g. taking muscle biopsies and valid efficiency measurements of sufficient Pro riders over say a 10 year career) are pretty rare.

Do one-legged drills if you are bored shitless, or want to become a world class one-legged rider.

The Kautz data, much like the Coyle et al data, simply demonstrates that it's all about the downstroke.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby twizzle » Sun Nov 22, 2009 4:06 pm

Fair enough, Alex, but I'm wondering about the science rather than me doing non-scientific experimentation... or listening to the huge amounts of B.S. on the net saying 'this is the way' without any basis (no, not you, you tend to qualify and reference everything you say).

I understand that, ultimately, it comes down to "what you have trained", but I'm wondering if I should be trying to generate power over more of the pedal stroke and what the positives/negatives are. And without having force measurement on my own pedalling, I have no idea if I'm starting to make significant torque at 5 degrees ATDC or 15 degrees, etc., and how this compares with the curve of the pro's - and potentially it's a lot of muscle/neuro I should be training. Given one of the studies above, efficiency wasn't impacted by adopting a circular pedalling motion vs. 'preferred' pedalling so there don't appear to be any negatives in spreading the work across more muscles.

My big questions (after a lot more research over the last couple of days) is : does spreading the load across more muscles during high-output sprints reduce the negative effect of heavy muscle contractions ie. reduced blood flow? Or in other terms, if you only produce power over a small part of the circle (which is what I think I've been doing), is this equivalent to trying to make power at low cadence where the muscle can't recover? And by spreading the load over more muscles to make power, can I use more of the aerobic engine because the contractions will be less intense and use less fast-twitch muscle?
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Alex Simmons/RST » Sun Nov 22, 2009 6:25 pm

Irrespective of pedal stroke, efficiency etc, all that matters is the power you can produce for given durations. So go ahead and experiment.

But here is the advice I give most when they've asked about pedaling:
- make sure you have a well fitted bicycle (all aspects)
- focus on effort level/power
- train smart

Pedaling will then take care of itself.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby twizzle » Mon Nov 23, 2009 5:41 am

Thanks Alex.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Alex Simmons/RST » Mon Nov 23, 2009 11:08 am

twizzle wrote:Fair enough, Alex, but I'm wondering about the science rather than me doing non-scientific experimentation... or listening to the huge amounts of B.S. on the net saying 'this is the way' without any basis (no, not you, you tend to qualify and reference everything you say).

I gotta say, it sure isn't helped by the amount of bulldust that is perpetuated, even by those that really should know better. So your queries are fair enough. Even the stuff put out by Lim (Saris) and Horowitz (Pez) recently makes me really wonder what they are smoking at times. Horowitz I can live with - he's a coach and goes with his experience and belief, each to their own if you are a belief-based coach, but I expect better from the scientist, Lim.

I've also had some interesting email conversations with a specialist in the field of amputee cycling research in the USA. They have full laboratory testing equipment for pedal forces etc etc and have validated the previous data wrt one-legged pedalling impacts, i.e. it simply bears no resemblance to normal two leg pedaling - if you do it (or use for instance independent clutch cranks) our motor control mechanisms will simply adapt to the new way of pedaling, and as soon as we change back to normal pedaling, so our motor control reverts as well.

By the way, I am to be experimenting with isolated leg work myself, but using inertial weighted non drive pedal system. i.e. think about adding an 11kg mass to the opposite non-drive pedal.

I'm not doing this to help my power or pedalling efficiency or whatever, it's just personal experiment and one way to gain some idea of the power difference between my legs. I have been loaned the special pedals in order to "see what happens". I've only had a chance to briefly ride them, training too bloody hard at the moment to get a good test in! If I get a rainy day soon, they'll get a workout.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby twizzle » Mon Nov 23, 2009 11:25 am

I came across your discussion on Slowtwitch yesterday. Bit nasty over there, aren't they!

With regards to people 'reverting' on standard pedals - not entirely true. I can't ride without clipless pedals any more as my feet come off the 'standard' pedals as they come across the top. I'm sure if I was to ride stock pedals for a while I'd learn the knack again, and would then have to adjust back to clipless again. But with something like PC's, which appear to simply require you to learn to pull the pedals around, I expect most of this would 'stick' if the rider actively thinks about the pedalling action. I'm certainly find it easier to develop consistent power when I actively 'think' about what both feet are doing.

I did some more 'playing' today - mainly trying to work out why I get a power jump when I go onto the drops. I think it's because I use the quads more and start applying force earlier in the pedal stroke before the pedal reaches TDC. The effect is very consistent, going from 250 - 280W on the hoods to 320 - 340W on the drops without any conscious change to pedalling.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby colafreak » Mon Nov 23, 2009 11:51 am

twizzle wrote:I did some more 'playing' today - mainly trying to work out why I get a power jump when I go onto the drops. I think it's because I use the quads more and start applying force earlier in the pedal stroke before the pedal reaches TDC. The effect is very consistent, going from 250 - 280W on the hoods to 320 - 340W on the drops without any conscious change to pedalling.


Does it stay this way? I.e. you're not just saying that when you go into the drops you see the power go up? You're saying that you can maintain that 320-340 for the same period of time you can maintain 250-280 (and no more) on the hoods for?
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby twizzle » Mon Nov 23, 2009 12:21 pm

colafreak wrote:
twizzle wrote:I did some more 'playing' today - mainly trying to work out why I get a power jump when I go onto the drops. I think it's because I use the quads more and start applying force earlier in the pedal stroke before the pedal reaches TDC. The effect is very consistent, going from 250 - 280W on the hoods to 320 - 340W on the drops without any conscious change to pedalling.


Does it stay this way? I.e. you're not just saying that when you go into the drops you see the power go up? You're saying that you can maintain that 320-340 for the same period of time you can maintain 250-280 (and no more) on the hoods for?


That would be 'No' - mainly because of the linked study in the first post that shows that gross efficiency should be unchanged which means that Oxygen uptake will be increased for the extra power, and while LT *might* have changed it's improbable that it would be 40+ watts worth. And without lab testing, I can't see any easy way (short of stupidly long rides) to see if my lactate threshold is different between hoods/drops. I can try this on the trainer, but I'm sure there are a lot of variables (ie. fatigue level) which would make this hard to quantify. Besides which - my back can't take long periods in the drops.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Alex Simmons/RST » Mon Nov 23, 2009 2:36 pm

twizzle wrote:
colafreak wrote:
twizzle wrote:I did some more 'playing' today - mainly trying to work out why I get a power jump when I go onto the drops. I think it's because I use the quads more and start applying force earlier in the pedal stroke before the pedal reaches TDC. The effect is very consistent, going from 250 - 280W on the hoods to 320 - 340W on the drops without any conscious change to pedalling.


Does it stay this way? I.e. you're not just saying that when you go into the drops you see the power go up? You're saying that you can maintain that 320-340 for the same period of time you can maintain 250-280 (and no more) on the hoods for?


That would be 'No' - mainly because of the linked study in the first post that shows that gross efficiency should be unchanged which means that Oxygen uptake will be increased for the extra power, and while LT *might* have changed it's improbable that it would be 40+ watts worth. And without lab testing, I can't see any easy way (short of stupidly long rides) to see if my lactate threshold is different between hoods/drops. I can try this on the trainer, but I'm sure there are a lot of variables (ie. fatigue level) which would make this hard to quantify. Besides which - my back can't take long periods in the drops.

Since the metabolic drivers are the same for riding a (longer) TT effort as they are for riding at much lower power, e.g. at LT, then all it requires is to ride a TT in both positions. No need to ride for extended periods in order to know the answer.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby Alex Simmons/RST » Mon Nov 23, 2009 2:39 pm

twizzle wrote:But with something like PC's, which appear to simply require you to learn to pull the pedals around, I expect most of this would 'stick' if the rider actively thinks about the pedalling action.

I can't recall where unfortunately, but my understanding of the research on using such cranks is that the body does indeed revert to prior motor recruitment patterns and that such adaptations are short lived.
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Re: Pushing down harder vs. perfect circle, and power cranks

Postby colafreak » Mon Nov 23, 2009 2:59 pm

Went for an 18k ride with the Grandfather on the weekend. I rode his old peugeot with flat pedals. My feet kept coming off the pedals on the upstroke, especially on the hills. This is even at an extremely low intensity.
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