# Crank arm length



## Andrew1971 (20 May 2014)

Hi All
What is the most common crank arm length for single speed.
Many thanks
Andrew


----------



## GGJ (20 May 2014)

170mm for roads is the most common, 165mm for track


----------



## Andrew1971 (20 May 2014)

Just had a look on my giant defy 5 the crank arms are 172.5 would they be ok or to long.
Many thanks
Andrew


----------



## KneesUp (20 May 2014)

Yours are only 1.5% longer than the most commonly used size - I think you'll be fine


----------



## Andrew1971 (20 May 2014)

Cheers for the info Kneesup. Looks like i need a smaller front chain ring that should stop me knees hurting grinding away on a to big a chain ring


----------



## GGJ (20 May 2014)

I doubt if you would notice any difference between 170mm and 172.5mm

What size chainring are you running and what size sprocket on the rear?


----------



## 4F (20 May 2014)

One of my fixed gear bikes has 165 and the other 170. Can't say I really notice the difference


----------



## Andrew1971 (21 May 2014)

Hi all 
Solved it I put different pedals on it there are flat ones so no straps or clips of any kind.so my feet find
their own position that's comfortable. 
Many thanks
Andrew


----------



## Dan B (21 May 2014)

The biggest reason for thinking about crank length on fixed is the possibility of grounding out a pedal when going around bends. Which can be very painful, but the chance of it happening does depend a lot on bottom bracket height


----------



## GrumpyGregry (21 May 2014)

Dan B said:


> The biggest reason for thinking about crank length on fixed is the possibility of grounding out a pedal when going around bends. Which can be very painful, but the chance of it happening does depend a lot on bottom bracket height


and angle of attack when cornering.

That said I caught a pedal when bolt upright, filtering between a black cab and a pedestrian refuge kerb, in central once.


----------



## Acesand8s (21 May 2014)

Dan B said:


> The biggest reason for thinking about crank length on fixed is the possibility of grounding out a pedal when going around bends. Which can be very painful, but the chance of it happening does depend a lot on bottom bracket height


The other reason is a better rpm range, especialy for a higher rpm, smaller is better. There are legal standards for the track,bottom bracket clearance is another standard, so you dont hit the ground, and might even matter more than crank arm length.


----------



## dave r (21 May 2014)

I'm on 165 on my fixed, I find it makes spinning up on a descent easier.


----------



## kloeshuman (27 May 2014)

where you see the difference is toe overlap, I normally run 170/ 172.5 and a new set I picked up were 175, you have to watch that


----------



## Basil.B (2 Jun 2014)

I ride a 165mm.


----------



## YahudaMoon (3 Jun 2014)

Track bikes must have a fixed wheel, 165mm cranks, and 280mm (11”) bottom bracket height 
(measured from floor to centre of bottom bracket)

Here. if your riding track

http://www2.nationalcyclingcentre.com/documents/Track bike specification.pdf


----------



## Trull (3 Jun 2014)

Keep a crank at arm length? wrong forum mate!


----------



## Sharky (3 Jun 2014)

150mm on my two fixed bikes and training gears bike.
145mm on my geared TT bike

Keith


----------



## Acesand8s (4 Jun 2014)

YahudaMoon said:


> Track bikes must have a fixed wheel, 165mm cranks, and 280mm (11”) bottom bracket height
> (measured from floor to centre of bottom bracket)
> 
> Here. if your riding track
> ...


----------



## fossyant (4 Jun 2014)

Sharky said:


> 150mm on my two fixed bikes and training gears bike.
> 145mm on my geared TT bike
> 
> Keith


 
Think you are 20mm out on both


----------



## Sharky (4 Jun 2014)

fossyant said:


> Think you are 20mm out on both


Nope - short cranks are really good (145 & 150)

Cheers Keith


----------



## totallyfixed (4 Jun 2014)

I'm on 175's, perfectly fine, getting on for 50,000 miles and never grounded a pedal, you would have to be leaning over at one hell of an angle to get pedal strike. On the plus side you get a bit more leverage for hill climbing and on the down side [literally] descending gets interesting although I have managed 200 rpm which I will not be repeating any time soon. 
If you are not convinced just lean your bike over with the pedal at the bottom.


----------



## fossyant (4 Jun 2014)

Sharky said:


> Nope - short cranks are really good (145 & 150)
> 
> Cheers Keith


 
Where the hell do you get them - rocking horse droppings come to mind ? You must be a short ar$e !!


----------



## fossyant (4 Jun 2014)

170's on my two geared road bikes, 170 on the fixed road bike, and 175's on the MTB - don't notice a difference. Got the 175's recently as they were on an incredibly cheap deal.


----------



## Sharky (4 Jun 2014)

fossyant said:


> Where the hell do you get them - rocking horse droppings come to mind ? You must be a short ar$e !!



Normal height. 5' 9". If anything, slightly longer legs.

Two pairs are Sinz expert
http://www.evanscycles.com/products/sinz/expert-square-taper-bmx-cranks-ec045038
And two I had re drilled by 
http://www.highpath.net

Increased cadence is possible and better position with saddle 2cm higher, especially on TT bike.

Lots of discussions on the net.

Cheers keith


----------



## Acesand8s (4 Jun 2014)

Yes i think he either measured from the spindle border to the crank border, or is very short and has custom made crank arms...


fossyant said:


> Think you are 20mm out on both


----------



## Acesand8s (4 Jun 2014)

And record breaking cadence was done on a 165mm so id watch the speculation. 325 i think somewhere around there.


Sharky said:


> Normal height. 5' 9". If anything, slightly longer legs.
> 
> Two pairs are Sinz expert
> http://www.evanscycles.com/products/sinz/expert-square-taper-bmx-cranks-ec045038
> ...


----------



## Sharky (5 Jun 2014)

Photo showing the difference between my old 175mm crank and The SINZ crank at 145mm

Believe it or not, but you soon adapt to the difference and with the saddle raised by about 3 cm to keep the distance at the bottom of the stroke the same, it actually gives an additional 6 cm between the pedal at the top and the saddle, which means the legs don't hit your stomach and you can have a much more efficient pedal stroke.

I'm sure not for everybody, but as you get older things like this help and certainly helps to get in the aero tuck position.

Cheers Keith


----------



## Andrew1971 (6 Jun 2014)

Hi all 
Thank you all for the replys. I have solved the problem with the length just put different pedals on.
Then went out for a ride then the crank bolt came loose now one buggered left crank arm.
Many thanks
Andrew


----------

