crank arm length?

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crank arm length?

Post  kumagako on Fri Mar 18, 2011 10:29 am

Today manufacturers of cranksets limit the cranklength sizes from 170-175mm.
The height of the rider will then largely dictate the length you need.
Smaller guys end up at 170mm while taller guys at around 175mm.

Got some data on crank length and BB-saddle height and their ratio of pro riders.

Boonen - 177.5mm - 80cm - 2.22 (177.5/80)
Gesink - 175mm - 83.5cm - 2.1
Sastre - 170mm - 72.5cm - 2.34
Cavendish - 170mm - 70cm - 2.43
Armstrong - 175mm - 75cm - 2.33

The idea is to maintain the ratio near these values maybe 2.2-2.3.
If anyone would notice, armstrong doesn't ride low much compared to others in the TT position.

Mine now is 170mm - 76cm - 2.23
2 years ago is 172.5 - 75cm - 2.3

There is no difference on the feel when pounding the pedals or I am just body-deaf.
The big noticeable difference is that I can take a much lower position on the bike.
A smaller cranklength will need to increase the height of the saddle
thus giving a wider hip angle on the top of the stroke
which I can use to crunch lower and go aero without losing power.



DISCLAIMER: this is not exact science just another level of analysis deeper when choosing the crankarm length.
The best fitter (no bike shop) with a adjustable bike may give you the optimal crank arm length according to the measurements of your leg, foot and pubic hair.



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Re: crank arm length?

Post  Makoy on Fri Mar 18, 2011 12:20 pm

Then I will need to change my crank to 154mm....

Not a good idea... palo

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Re: crank arm length?

Post  kumagako on Fri Mar 18, 2011 4:10 pm

Makoy wrote:Then I will need to change my crank to 154mm....

Not a good idea... palo


not a good idea kung nakabili kana ng crank
kaso it is a good idea to improve biomechanically on the bike.

"the bike should fit you and not you fit the bike"
stating in another way
"it is the bike that goes for a bikefitting to fit you and not you to be fitted into the bike"

155mm cranks can be customized only so use the 165mm.


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Re: crank arm length?

Post  Kiko on Fri Mar 18, 2011 4:58 pm

theoretically pwede... patira mo kay sulaiman! wehehehe

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Re: crank arm length?

Post  GIANT on Fri Mar 18, 2011 6:07 pm


so how? ano sukat ko? anu po yung fit sa height ko na 5'10 (178 cm ata). suggestion po... thanks

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Re: crank arm length?

Post  akosivlad on Fri Mar 18, 2011 9:18 pm

when cycling I tend to shift around on the saddle which I think makes more impact than crank length.

If you are stuck with whatever crank length you have, work on your pedalling technique instead.

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Re: crank arm length?

Post  Proud2bpinoy on Fri Mar 18, 2011 11:03 pm

Si voeckler ata ito ah.

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Re: crank arm length?

Post  skid on Sun Mar 20, 2011 1:11 am

i'm using:

170mm road bike
175mm mtb; low cadence... like the extra leverage but hate the feeling of pedalling a big circle. i need suggestions on this.

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Re: crank arm length?

Post  kumagako on Sun Mar 20, 2011 1:38 pm

skid wrote:i'm using:

170mm road bike
175mm mtb; low cadence... like the extra leverage but hate the feeling of pedalling a big circle. i need suggestions on this.


financial help?

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Re: crank arm length?

Post  Kiko on Mon Mar 21, 2011 11:45 pm

skid wrote:i'm using:

170mm road bike
175mm mtb; low cadence... like the extra leverage but hate the feeling of pedalling a big circle. i need suggestions on this.


MORE TRAINING? ride

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