Crank Arm lengths

[veyron.]

Hey! Could anyone help me. How do you know what length of crank arm you should use? and what difference does it make? how do you decide?

Thanks

 

 

[Zaskar]

A 2 second Google search reveals...

http://www.nettally.com/palmk/crankset.html

http://www.nettally.com/palmk/crimplic.html

http://www.cptips.com/crnklth.htm

http://www.machinehead-software.co.uk/bike/cranks/cyclist_crank_length_calculator.html

http://www.bicyclesource.com/bike/fitting/crank-length.shtml

http://www.billbostoncycles.com/crank_length.htm

http://www.bicycletouring101.com/BikeDifferentCranks.htm

[veyron.]

Thanks Zaskar!!!!

[The Guy in Pink]

Depends on your height, disipline and riding style.

Height : short guys would use a shorter crank, tall a longer one . 

On the road that will be 170mm to 177.5mm normally, with 172.5mm being most popular. 

Sprinters  prefer a shorter crank, climbers a longer one.

For Time Trials cranks longer cranks coupled with chain rings with not much difference in size (48 & 50 tooth) are useful, and a normal  crank on the track would be 165mm.

Tandems usually  push bigger gears so can use a 180mm crank  to advantage .

Us older guys also benefit from a longer crank so I have 180mm cranks although I am only just over 6 foot.

[veyron.]

Oh ok. I am 1.77m tall. What would be my ideal crank arm length?

[Jason]

I'm 1.77m and use 172.5

[Mudsimus]

I'm 186 and always used 175. Had permanent knee trouble. Changed to 172.5 this year...will never ride 175's again.

[veyron.]

I think I have a 175 on at the moment. very happy with it! If I were to change to a 170mm would it make a big diff in anyway? bad or good?

[oclv110]

I used to ride 172.5 mm cranks and then tried 175 mm on my new bike.I am 1.74 m tall and must admit that I prefer the longer cranks.It was almost like having an extra gear.I was a little concerned about knee pain but have been on the new bike for about a month now and nothing what so ever. Someone told me that I will have trouble with my cadence(keeping it up )on steep climbs but I haven't experienced that either.I ride a 11-23 cluster on training and a 12-25 on race day.

[The Guy in Pink]

How tall are you?

Do you spin or push big gears? 

If you are happy with 175mm why do you want to change?

[Jason]

I'm 186...

You must be another Moses in the making... Did that SRM stuff work?

[veyron.]

 

How tall are you?

Do you spin or push big gears? 

If you are happy with 175mm why do you want to change?

 

I am 1.77m tall. I generally spin av cadence when climbing is around 100-110rpm. Might be upgrading my cranks and can only get  in 170mm.

 

[Mudsimus]

I'm 186...

You must be another Moses in the making... Did that SRM stuff work?

 

Like a dream

 

Thanks

[Buff]

Something I find really strange is that road bikes come out with a 172.5 standard and mtb's with a 175 standard, why the difference? One would think mtb's cranks would be shorter to give more ground clearance or are they longer to give more leverage in those granny gears?

So many questions... where's mr boredman

 

Having said that, I also recently (9 months ago) moved up to 175's on the roadbike and I'm finding them way better than the 172's. It's difficult to pinpoint where they are better but I definetly find I climb better with them. However, on the flat roads I struggle to spin the bigring in anything lower than a 18 at the back, so I keep it in the 39 and drop it down at the back (this is while training, while racing it's in any gear that makes it go forward fastest).

btw, i'm 1.74m tall... or rather... short.

[The Guy in Pink]

I am 1.77m tall. I generally spin av cadence when climbing is around 100-110rpm. Might be upgrading my cranks and can only get  in 170mm.

 

Then do not upgrade. If you happly spin at 110rpm on a 175mm crank do not do the change unless you can get the right lenght. 

 A Prettier colour in the wrong length crank is not much of an upgrade IMHO