Crank length confusion

Discuss light weight issues concerning road bikes & parts.
wwnick
Posts: 106
Joined: Wed May 10, 2017 8:49 pm

by wwnick

ZED 2 CRANKSET: The French Swiss Army Knife of Cranksets
Ultralight and rigid, compatible with all pedals. Adjustable arm length 170/172.5/175mm. Compatible with 110 and 130mm bolt patterns: double and compact.
https://www.lookcycle.com/en/components-bicycles/

I went from 175 to 172.5 and it felt better, maybe even 170 could be good but with integrated powermeter, little chance of changing that soon.
Regards Quintana, his team mate Valverde who is, obviously, taller rides 170mm. small is not bad it seems but maybe best not to overthink it.

by Weenie


User avatar
wheelsONfire
Posts: 1808
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

I rode 172.5 all the time. But i was persuaded i should have 175.
So i bought a Rotor 3D+ and 52/36 Q-rings. The crankarms was trouble between 10- 2 o'clock.
I could not pedal smooth so it was quite obvious i had to realize they were not for me.
Switched back to 172.5 and it felt better. However, i borrowed my buddies 170mm cranks and those where better than 175mms.
But i noted i kind of pedaled in a too large circle. I guess i could adapt better to 170 than 175.
An old GF i had, had shorter cranks on her MTB, i don't know if it was 170-167.5or 165.
That also felt much better than the 175mm version i had on my own bike.
Bikes:

Ax Lightness Vial EVO D
Paduano Racing Fidia
Open *UP*
https://opencycle.com/showcase/the-xplo ... eelsonfire

alcatraz
Posts: 850
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Shorter cranks are easier to spin but if too short you can't put out a lot of power out. (torque)

Balance is between comfortable knee angle and power.

If you don't have discomfort then maybe go with the recommended crank for your inseam.

If you have the luxury to try different lengths on the same bike, and do some real testing of power/time, then you can really choose the optimal crank for you.

I used to ride too long arms and after reading an article that my inseam 82-83 cm suits a crank of 170mm that was 2.5-5mm shorter (can't remember) i have to say the difference was quite huge. It just feels right.

I doubt going even shorter will improve things. I'm a small rider and torque is my weakness. Don't want to just eliminate any ability to generate it.

/a

User avatar
wheelsONfire
Posts: 1808
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

morganb wrote:
wheelsONfire wrote:I have different saddle height with different saddles.
I ride Cobb Randee (generation 1 = not the one available now)
This saddle has quite a bit of hull flex and all padding you need, is in the saddle.

I am at about 78cm.
I am also not using traditional bib shorts (with fat chamois that is)
Pedals are Mavic CrossMax SL Pro and Giro VR-90 shoes.

You could say, i am almost exactly on, inseam length * 1.09 from top of saddle to center hole of crankarm (where you insert pedal).

Something seems wrong with you arriving at 185-190. My BB to top of saddle with a Toupe and 155mm is 71.8cm. Possibly the way you measure inseam compared to the way Zinn recommends. I know he's a proponent of long cranks for very tall riders (himself included) but I don't think you would fall into that category.


I measure the distance between my feets (clipped in when i pedal), then from floor and up (i use a book)
Mark the height and then re-do a few times to see if it's same.

What is Zinn method, is it when you measure along your legs and up to crotch?

I feel there is so much with this, what shoes do i have, what pedal system, how long feets do i have.
Where do i position my cleats.
Pedal style, heels up or horizontal. Do i use fat padded bibs or no pads (also affect saddle set back).
Am i using a stiff shell saddle or a saddle with flex... bla bla...
Bikes:

Ax Lightness Vial EVO D
Paduano Racing Fidia
Open *UP*
https://opencycle.com/showcase/the-xplo ... eelsonfire

User avatar
wheelsONfire
Posts: 1808
Joined: Mon Jul 07, 2014 8:15 am
Location: NorthEU

by wheelsONfire

Circumference difference is 1.56 cm
Bikes:

Ax Lightness Vial EVO D
Paduano Racing Fidia
Open *UP*
https://opencycle.com/showcase/the-xplo ... eelsonfire

Post Reply
  • Similar Topics
    Replies
    Views
    Last post