Lower cadance - more power?

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Kermithimself
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by Kermithimself

I'm having a discussion on a danish board, whether or not your cadance affects your power. His statement is that at a lower cadance - such as 80 rpms, you will produce more power with a lower heartrate, compared to if you ride with a higher cadance such as 100 rpms. We're talking FTP testing.

My theory is that in order to keep a pace of, say 40 km/h, you need to produce x watts. If you do 400 watts at 80 rpm, or 400 watts at 100 rpm, doesn't matter.

But by using a higher cadance you will more likely not build that much lactat acid, as you would at a lower cadance. Right?

What's the general idea on this, and has there been made any avaliable reports on the subject?
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Giant DK
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by Giant DK

My experience is that my heartrate i lower at lower watt. Take for example a 10 min powerinterval, which is around 290 W with 50 rpm for me, my heartrate is lower than if I rode 290 W for 10 min with 100 rpm. It sure doesn't feel easier but my heartrate is lower. After beginning riding with power I nearly never look at my heartrate anymore.
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darkblue08
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by darkblue08

From what I have discovered through me own rides is that. I have a lower heart rate at low cadence compares to high cadence, but I get tired more quickly at low cadence. As a result I ride TT at a high cadence compare to my normal average. I also get higher heart rate when in the drops, but I don't have to put out as much power to maintain the same speed in a headwind. (Im also from Denmark). I also has a theory that it depends on if you sit back (like climbing a mountain) are in the bar-tops or in the drop
I have tested this on an indoor train, and with a power meter outside.
Which Danish forum are you using?

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Kermithimself
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by Kermithimself

Cool. It's Motion-Online.dk in my log "Kermits Cykeleventyr" :wink:

The part about producing more watts when climbing I think is because you're sitting more upright, and often get out of the saddle for variation, which you seldom do riding flat.

But cool with some IRL experiences :D
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Tapeworm
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by Tapeworm

Well you wouldn't be producing much lactic acid, period.

IIRC, there is a study floating around which showed low cadence (~60rpm) was more efficient for TT style efforts.

By the nature of the human body increasing the number of muscle contractions will inherently raise the metabolic cost to the body. However this is not the same as power output. There is a limit to the amount of torque that can be sustained by slow twitch muscle fibres over time.

Generally the best cadence for power is the one that yields the most power for a given time. This is dependant on the individual and the corresponding power output.

Quadrant analysis through power meters show general trends for this but there are aways outliers. Google Wattage Groups has plenty of reading on this.
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Geoff
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by Geoff

I have seen that in my own Intervals over the years. If I am 'on the rivet' at the end of a long Interval, I will sometimes grab a bigger gear and change cadence to keep the watts up. The problem with that observation is that low-cadence power may not be sustainable for long periods of time and may 'artificially' alter your test results.

bricky21
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by bricky21

Kermit, what your missing is that power is the multiplication of torque/force and velocity/rmp's , so while we can put out more torque at lower rpm's it has to be high enough to compensate for the lesser velocity to indeed produce more power , and that is were the sustainability and individuality issues come into play.

WasFab
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by WasFab

bricky21 wrote:Kermit, what your missing is that power is the multiplication of torque/force and velocity/rmp's , so while we can put out more torque at lower rpm's it has to be high enough to compensate for the lesser velocity to indeed produce more power , and that is were the sustainability and individuality issues come into play.

yes but is it still true that lower cadence with more torque will increase or decrease lactic acid in the muscles? For long term what will create more fatigue? Not that we can compare ourselves I guess, but according to Lance Armstrong one should ride on velocity of 90-110 rpm. That means on lower gears.

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Juanmoretime
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by Juanmoretime

I've experienced the same as others here. My cadence in a tt is usually 65 to 70 rpm. At a higher cadence I find it harder to create power. My heart rate is lower too at lower cadence.

Not a great tt but alright.

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mrfish
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by mrfish

My experience is that low cadence might help get a result a TT, it didn't work in the long term.

I by riding a 10m TT at full gas at 70rpm my legs would be wrecked for 3-4 days, whereas if I stuck with 90+ rpm I'd be training again in a day. Over the weeks of a season the recovery time adds up, and in addition beating yourself and making your legs hurt for days discourages really hard sessions. Overall I tended to do my best rides using a moderate gear "pedalling through syrup", rather than trying to stomping on the pedals. Whether that was training or ride related I couldn't say.

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Rick
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by Rick

Kermithimself wrote:My theory is that in order to keep a pace of, say 40 km/h, you need to produce x watts. If you do 400 watts at 80 rpm, or 400 watts at 100 rpm, doesn't matter.


This is why, one of my favorite sayings (and a hit among other old engineers like myself) is "In theory there is no difference between theory and reality. But in reality, there is always a difference."

Even in machines it matters, so I don't find it odd at all that it does matter in humans.
I too find that I can get a lot higher power at lower heart rate with low RPM's. In fact, I have found it amazing that if I am following a good climber, and I get stuck in 'too high a gear', I can maintain contact (for a while) until I downshift to a "more efficient" gear.....where I see them just creep away from me.

I don't have an explanation, but it must have something to do with muscle biochemistry and things outside the realm of pure power mechanics. Undoubtedly there are individual differences too.

airwise
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by airwise

I suspect the answer depends on your metabolic make up and one solution may not apply to everyone.

There simply cannot be one rule for all as our bodies are constructed differently. We all have an optimal cadence. Finding it is remarkably helpful.

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devinci
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by devinci

The best cadence is relative to each individual and depends on the terrain you are riding on, as well as wind, effort/duration...

My 2 cents

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LouisN
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by LouisN

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Last edited by LouisN on Tue Mar 27, 2012 1:54 pm, edited 1 time in total.

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darkblue08
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by darkblue08

Uhhh, flamebait. To ride with or without underwear :)

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