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The crank length thread

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Re: The crank length thread

06 Jan 2017 16:13

sciguy wrote:
shorter cranks wrote:115mm crank Update

Anyway to my surprise again I haven't noticed any drop in power at all. .


So you're using a power meter and actually measuring your power? How's your mean maximal power at 1 minute, 5 minutes, 20 minutes and one hour compare to the longer cranks?

Thanks,

Hugh


No I don't have a power meter, although I would like to own one. All my findings are based on my cycle computer's speed and average speeds, most of the time I am comparing my speeds on a 20klm loop I do to work and back that I've been doing for 20 years, so I know the road, my top speeds my average speeds like the back of my hand. Part of the ride has a fairly tough hill that climbs for about 2klm reasonable steep and constant, my good friend said his GPS averaged ihat at 11- 12%, so a good test. I have timed myself many times over the years on that hill, the best time I have ever done is on the 120mm cranks, I haven't timed myself on the 115's yet but 3 days ago I'm almost certain I was faster based on speedo readings the whole way. On that same ride there is a very long flat section about 7klm, that's where I noticed my biggest improvements, I could never hold it much above 46klm on the 175's, but since going below 130mm I can handle 50klm for quite a bit of that distance. Again flat riding holding high constant speeds(TT) is where I have improved the most. Hill climbing is only slightly faster, but seems to be at it's best on 115's. Sprinting top speed I always do on the same section of road(fairly flat and smooth), I have done it many times on the 175's and my highest ever was 56klm, my highest speed on the short cranks is 59klm that was on 130mm cranks, on the 115's my top speed is almost as good 58klm but I can hold it longer at higher speeds. I will say my initial of the mark sprint speed is definitely snappier on the longer cranks like 155mm-165mm.

All my findings are obviously not results down on paper but I have no doubt myself that I am performing considerably more efficient on the shorter cranks(I wont go back to anything longer than 130mm). And as I have mentioned before I don't suffer with chronic low grade pain like I did with the 175's.
shorter cranks
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Re: The crank length thread

06 Jan 2017 16:58

backdoor wrote:
shorter cranks wrote:115mm crank Update


Again as I mentioned in one of my earlier posts, the shorter I go, the harder I pull up on the upstroke, there are no dead spots in the pedaling stroke, just strong through the whole circle.


Cheers.


In your estimation when at maximal power application, what percentage of your torque at 3 o'c are you applying at 9 and 10 o'c, and what do you mean by "no dead spots in the pedaling stroke" ?


I will try my best to explain.
Once I progressed down to about 140mm, I started to notice to achieve good power at that length It was almost natural to pull up to a certain degree through what felt like about 8 to 10/11 during the upstroke which then makes the down stroke from about 1/2 to 5/6 feel more lively I guess. But once I dropped below 125mm this pedaling technique/sensation becomes almost instinctive and very easy to achieve. On 175's I never pulled up on the upstroke, I found it hard enough to get my foot over the top of the stroke (12) little own pull up!

Now what I mean by no "dead spots" is with lengths below 130mm it feels like I am not only pulling up and pushing down hard but I also feel like I push the pedal forward with force over the top of the stroke 11 to1/2 and pull back through the bottom of the stroke as well from 5 to 7/8 again with force. So no dead spot where not torque is applied to the pedal.

Obviously, well I assume in reality peak force would be at it's greatest on the down stroke 3 to 5. But it feels like I am Pulling up and around the back as hard as I am pushing over down the front.

So I am certain that I apply more even torque around the entire pedal stroke than I can with longer cranks (only pushing hard through the down stroke).

I hope I didn't confuse you?
shorter cranks
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Re: The crank length thread

07 Jan 2017 19:05

shorter cranks wrote:
backdoor wrote:
shorter cranks wrote:115mm crank Update


Again as I mentioned in one of my earlier posts, the shorter I go, the harder I pull up on the upstroke, there are no dead spots in the pedaling stroke, just strong through the whole circle.


Cheers.


In your estimation when at maximal power application, what percentage of your torque at 3 o'c are you applying at 9 and 10 o'c, and what do you mean by "no dead spots in the pedaling stroke" ?


I will try my best to explain.
Once I progressed down to about 140mm, I started to notice to achieve good power at that length It was almost natural to pull up to a certain degree through what felt like about 8 to 10/11 during the upstroke which then makes the down stroke from about 1/2 to 5/6 feel more lively I guess. But once I dropped below 125mm this pedaling technique/sensation becomes almost instinctive and very easy to achieve. On 175's I never pulled up on the upstroke, I found it hard enough to get my foot over the top of the stroke (12) little own pull up!

Now what I mean by no "dead spots" is with lengths below 130mm it feels like I am not only pulling up and pushing down hard but I also feel like I push the pedal forward with force over the top of the stroke 11 to1/2 and pull back through the bottom of the stroke as well from 5 to 7/8 again with force. So no dead spot where not torque is applied to the pedal.

Obviously, well I assume in reality peak force would be at it's greatest on the down stroke 3 to 5. But it feels like I am Pulling up and around the back as hard as I am pushing over down the front.

So I am certain that I apply more even torque around the entire pedal stroke than I can with longer cranks (only pushing hard through the down stroke).

I hope I didn't confuse you?



As cadence increases your upstroke muscles are only capable of eliminating negative torque and this will result in a weaker downstroke. The dead spot can only be eliminated by using a combination of equally powerful muscles in that sector as those used around 3 o'c.
backdoor
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Re: The crank length thread

08 Jan 2017 00:24

Hi Shorter Cranks:
Thanks for sharing your experiences. I have a question about your approach to changing seat height. When you change to a shorter length do you raise the saddle so as to maintain maximum leg extension? In other words, when you change to a 10mm shorter crank do you raise the saddle by 10mm? That's how we did the studies in my lab.
Another approach would have been to leave the saddle at the same height. This would give the same extension in the middle of the cycle (3 o'clock) but less extension at the bottom.
Anyway, would you share how you adjust your saddle?
Thanks,
Jim

shorter cranks wrote:115mm crank Update
PhitBoy
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02 Jun 2017 11:33

I definitely feel more energy efficient when I climb stairs one at a time (like with extremely short cranks), but I jump 3 at a time when I'am in a hurry. Probably somewhere in the middle is a place with reasonable balance between speed and endurance and since I need both on a bicycle then I feel that small differences around this middle aren't worth investigating.
talbet
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