Profiles' 145mm crank arms

yay or nay?

what?

Yay.

Do you have short legs?

the idea is that you use a lower gear but spin more to get same speed as a higher gear with longer cranks.

Could be more efficient as legs are not having to move in such big circles?

Unless you mean for mad barspin skills?

145's might be tricky to get. They're kids racing cranks. The magnatanium ones are used by a lot of flatlanders and come in small sizes though. They're light too

Very hard to skid with as you dont have much leverage. especially at speed

You will just spin like mad, I know dude who races bmx when he was a kid he had 145's still has them (he keeps everything he has) we put them on his single speed, it just failed, no pedal leverage knees never fully extended could ache after a while... not worth it...

Why anyway?

177.5 ftw

How big is your frame?!

72/70

As I typed what I just said I had a feeling it was going to be a large frame.. ;)

ye im 8'4" 3rd tallst man in britain

Impressive, are you boasting?

The shorter the cranks, the sorer the knees... This is a fact...

i just attach my pedals directly to the bb and hope for the best

Impressive, are you boasting?

no way, ask maxcrowe im 2 feet taller than him ;)

i just attach my pedals directly to the bb and hope for the best

Thats the best bar spin clearance he ever got.

I have actually used 140mm cranks on my lo-pro by way of experiment, dropping straight down from my usual 175s. Adaptation was very quick, and adjusting the gear to give the same gain ratio allowed me to go exactly as fast as on the long cranks/big gear set up. If you read the literature on the effect of changing crank length, this will not come as any surprise.

Since, by common consent, changing your crank length wont make you faster (or slower), the only reason to do it is either a: your range of joint movement constrains the upper limit of crank length (this applies to all of us eventually, but few of us are so constrained at common crank lengths up to 175), b: some geometrical feature of your bicycle or riding style impels you to reduce the crank length to gain clearance somewhere, or c: you're particularly concerned with the finer points of aerodynamics on a recumbulent™ or triathlon bike and think shorter cranks will enable a reduced frontal aspect.

You will just spin like mad, I know dude who races bmx when he was a kid he had 145's still has them (he keeps everything he has) we put them on his single speed, it just failed, no pedal leverage knees never fully extended could ache after a while... not worth it...

Why anyway?

Did he change his gear ratio?

Another topic covered by Burrows in his Bicycle Design book. Anyone interested in bikes such have a scan through his book as even though he just touches on subjects it does make you think about them (crank length, frame materials, tyre sizes etc,)

Cheers for the input, knee pain is the main reason for considering it (old injury), with the added bonus that it will help with the toe overlap problem on my set up.

145mm hahahaha thats the funniest shit that omfg. i gotta see this.

it's is not that big a difference though really is it?

Go from 175 to 165 and within a few days you would not notice it. It is only 10mm more than than.

Just do it and see what happens, but also take into account that no one on here has done it!
Meaning it might not be a good idea?
Do you want to bar spin?

Having used 155 cranks on my old polo bike I really can't recommend dropping to 145s.
Every slight inclined killed my knees. I would seriously reconsider your options.