Scientists say high cadence is inefficient

Boring_Username
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Scientists say high cadence is inefficient

Postby Boring_Username » 13 Feb 2019, 12:23pm

Apparently Chris Froome is doing it all wrong...

https://www.cyclingweekly.com/fitness/w ... ome-191779

This bit in particular surprised me:

When a rider pedals at a high cadence in a low gear, 60% of their power is used moving their legs up and down, while only 40% goes into turning the cranks... It is massively inefficient


60% of power is wasted? Can that possibly be true?

The implication seems to be that the most efficient solution would be one where 0% of power was used to move your legs up and down, but then the cranks wouldn't turn at all!

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mjr
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Re: Scientists say high cadence is inefficient

Postby mjr » 13 Feb 2019, 12:46pm

Could be true. It's always been a balance between efficiency (% of power reaching the drive) and effectiveness (total power).

You note that the most efficient would be ineffective, but this study just confirms that also the most effective is inefficient.
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ianrobo
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Re: Scientists say high cadence is inefficient

Postby ianrobo » 13 Feb 2019, 5:02pm

I wonder though about high cadence as really it is used for climbing and on the flat Froome and others do have cadences in the 70’s pushing higher gears

Marcus Aurelius
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Re: Scientists say high cadence is inefficient

Postby Marcus Aurelius » 13 Feb 2019, 5:21pm

Actually, long as you’re making sufficent power, higher cadences are more efficient. The problem comes when your power at 80-90 rpms isn’t high enough to cause the fast twitch muscles to be engaged forcefully enough.

https://www.active.com/cycling/articles ... =pepperjam

This explains it nicely. If you’re only making ( for arguments sake ) 90 Watts at 90 rpms, the effort required to move your legs at that speed negates any efficiency. At ( for arguments sake ) 120 Watts or above at 90 rpms , the losses involved in moving your legs that fast, are made increasingly insignificant by the efficiency of the way your muscles are fuelling themselves ( particularly the fast twitch muscles).

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Re: Scientists say high cadence is inefficient

Postby Marcus Aurelius » 13 Feb 2019, 5:34pm

ianrobo wrote:I wonder though about high cadence as really it is used for climbing and on the flat Froome and others do have cadences in the 70’s pushing higher gears


High force lower cadence pedalling forces the muscles to feed mostly on Glycogen / Carbs, and high force high Cadence pedalling forces the muscles to feed mostly from fat, so a rider with a low body fat percentage can’t afford to do high force High cadence pedalling for very long, and that’s why the skinny pros do it the way they do it.

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Tigerbiten
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Re: Scientists say high cadence is inefficient

Postby Tigerbiten » 13 Feb 2019, 5:58pm

It's actually "Scientists say high cadence is inefficient in low gears".
Which is correct as a low gear has a lower optimal cadence than a high gear.
So if you try and spin all gears at the same cadence then at some point you lose efficiency as the gear inches drop.

Luck ........ :D

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Re: Scientists say high cadence is inefficient

Postby mattsccm » 13 Feb 2019, 8:06pm

I believe that the article says that inexperienced/less fit cyclists are wrong to twiddle excessively. Froome etc are different.
I know we are all different but I have always maintained that spinning a very low gear fast is daft. My legs are at their best a a slower cadence.

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Re: Scientists say high cadence is inefficient

Postby mnichols » 13 Feb 2019, 8:44pm

This is useful, but I'm not sure that it's explained very clearly. I would have liked to see some cadence v watts numbers.

My indoor bike has a power meter and so I can measure power, cadence and effort (hrm or just how I feel) and I find this useful and surprising.

My watts for effort definitely drop at lower cadence (70, 60 or lower) and i push out my highest watts at higher cadence ( 90 to 100). The difference is over 100 watts, maybe even 150.

Although I can't sustain high watts high power, or very low cadence for a few minutes. Below a cadence of 60 it's more efficient for me to stand, and i practice doing this for around 30 minutes (longest was 45) or intervals

My sustainable best sustainable wattage is at around 90 rpm, although I occasionally practice spinning at 100 for an hour an ignore the watts

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Re: Scientists say high cadence is inefficient

Postby mnichols » 13 Feb 2019, 8:47pm

mnichols wrote:This is useful, but I'm not sure that it's explained very clearly. I would have liked to see some cadence v watts numbers.

My indoor bike has a power meter and so I can measure power, cadence and effort (hrm or just how I feel) and I find this useful and surprising.

My watts for effort definitely drop at lower cadence (70, 60 or lower) and i push out my highest watts at higher cadence ( 90 to 100). The difference is over 100 watts, maybe even 150.

Although I can't sustain high watts high power, or very low cadence for a few minutes. Below a cadence of 60 it's more efficient for me to stand, and i practice doing this for around 30 minutes (longest was 45) or intervals

My sustainable best sustainable wattage is at around 90 rpm, although I occasionally practice spinning at 100 for an hour an ignore the watts


So, for climbing is best for me to spin (90 to 100) and dropping to 60 loses me +100 watts, so I have gears which means I avoid this wherever possible. If a slope is very steep it's better and sustainable for me to stand

Knowing and using this gave me a respectable time over the 5000 meter peaks in the Himalayas last year where oxygen was low.

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Mick F
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Re: Scientists say high cadence is inefficient

Postby Mick F » 13 Feb 2019, 8:48pm

I don't use a high cadence, and when I try it, I feel that effort is wasted just cranking the legs up and down.
Average long term cadence for me is 67rpm.
Mick F. Cornwall

mnichols
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Re: Scientists say high cadence is inefficient

Postby mnichols » 13 Feb 2019, 9:00pm

Mick F wrote:I don't use a high cadence, and when I try it, I feel that effort is wasted just cranking the legs up and down.
Average long term cadence for me is 67rpm.


The reason I said mine was surprising was that before I had access to a power meter i would have said my optimum cadence was around 80. Whereas it turns out I'm pretty rubbish at that leg speed when looking at my wattage.

What I can see is that it's much better for me to turn my legs faster. This is more sustainable and I produce higher watts. I go faster, further and for less effort.

Have you had an opportunity to measure your watts at different cadences?

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Re: Scientists say high cadence is inefficient

Postby Cugel » 13 Feb 2019, 9:56pm

mnichols wrote:
Mick F wrote:I don't use a high cadence, and when I try it, I feel that effort is wasted just cranking the legs up and down.
Average long term cadence for me is 67rpm.


The reason I said mine was surprising was that before I had access to a power meter i would have said my optimum cadence was around 80. Whereas it turns out I'm pretty rubbish at that leg speed when looking at my wattage.

What I can see is that it's much better for me to turn my legs faster. This is more sustainable and I produce higher watts. I go faster, further and for less effort.

Have you had an opportunity to measure your watts at different cadences?


That's my experience - although without the power meter. I go on the results compared to what the group I'm in are achieving. I find it easier to keep up when at my physical limit if pedaling faster (around 90rpm) than when pedaling slower.

But the context makes a difference. For continuous effort over significant time (say 15+ minutes) spinning is best to keep up. For all out sprints and riding as a rouleur over bumpy roads with many short climbs, flats and descents, I find lower rpm allows me to push hard up the short ascents, with a (relative) rest on the short descents before the next ascent.

My feeling is that higher cadence allows m to keep up a continuous relatively high power output over significant time because my muscles don't fatigue. If I try the same speed in the same circumstances at low revs (say 60-70 rpm) my muscles tire before I run out of puff. At higher rpm the muscle pain is bearable and the puff is just below the limit (aerobic capacity threshold) - balanced, if you like.

At lower revs I can produce more power - but not for very long. This is why it works for bumpy rides where there's an oscillation between high power output and medium power output on the ascents and descents respectively.

When I was younger, we racey lads all had 42 X 21 as the lowest gear. Low cadence was thus a norm in many circumstances, particularly climbing. This is why we all had much more muscular quads in them days than many cyclists do these days, I feel. Low revs up hills is doing weight training. It was also very fatiguing and often saw lads blowing up rather than just losing contact for a little bit.

Cugel

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Re: Scientists say high cadence is inefficient

Postby Tigerbiten » 14 Feb 2019, 1:37am

I think what the article is trying to say is .....

If you want to tick along at about 15 mph then pushing a 60" gear at 85-90 rpm may not be as efficient as say pushing a 72" gear at around 70-75 rpm simply by the fact your legs are moving up and down to fast for your power output.
If you want to up your speed to about 20 mph then the higher cadences start to become more efficient because the proportion of power to the pedals vs power to spin legs becomes better.

YMMV ........ :D

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Mick F
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Re: Scientists say high cadence is inefficient

Postby Mick F » 14 Feb 2019, 8:41am

mnichols wrote:
Mick F wrote:I don't use a high cadence, and when I try it, I feel that effort is wasted just cranking the legs up and down.
Average long term cadence for me is 67rpm.


The reason I said mine was surprising was that before I had access to a power meter i would have said my optimum cadence was around 80. Whereas it turns out I'm pretty rubbish at that leg speed when looking at my wattage.

What I can see is that it's much better for me to turn my legs faster. This is more sustainable and I produce higher watts. I go faster, further and for less effort.

Have you had an opportunity to measure your watts at different cadences?
No.
Can't say it matters much to me at all.
If I try to spin the cranks faster, I get tired sooner. My cadence varies I'm sure, and there will be many time/places that I'll be up at 90rpm, but that's the absolute maximum and would be short distance.

The most relaxing gentle ride for me is on the level at about 10mph in top gear. Maybe 35rpm. Providing the road remains level, I could keep that up all day.
Getting a move on - say 15/18mph - the gear would be lower and the cadence higher.

PS:
I used to have a cadence sensor, but I sold it some years ago.
I have stats coming out of my ears, so I could analyse the cadence results from back then, but TBH, I don't care. I'm happy, so that's enough for me.
Mick F. Cornwall

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Re: Scientists say high cadence is inefficient

Postby mnichols » 14 Feb 2019, 8:13pm

Mick F wrote: I'm happy, so that's enough for me.


In the final analysis that's all that matters