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currently running 175s but have just ordered some new 165s...
i run a dh tram which has a very low bottom bracket, i run my shock pretty soft and have a shock in there which is slightly to short lowering the bb even more. all of this means its really easy to hit my pedals on the floor when pedalling through rough stuff. im about 5ft 8.
some people have said 165s will be too short but what down sides are there? can it mess your legs up or anything? reduce the amount of power you can put down, help or hinder acceleration???
(the cranks ive ordered had sold out of 170s so they werent an option)
cheers aj

always ran 165s on my dh bike as a youngun ...been 6 foot + since i was 13

in theory, it will be harder to pedal as you have less leverage on the cranks but you wont spin out as quickly.

but in the real world, you wont notice 10mm, might feel a bit wierd at first just because it is different.

175mm are really for xc bikes for leverage and helps if your over 5ft 10" to have them.

I ran 165 hones on my trail bike and I'm 6ft and they felt fine, bit spinny but nonetheless fine.

wouldn't want to go any shorted though.  ;D

I honestly can't feel the difference when pedaling between my different bikes but have definetly noticed the the difference at certain tracks when counting my pedal strikes.

I felt a difference between 175s and 170s when I switched over. I run quite large rings though, (40T mainly,) so the drop, however small, was noticeable. I'm a heavy rider and the wrong side of 30, so maybe that's against me too, but my knees ached even more than usual when using shorter arms, even only by 5mm. I may give the 170s another go with a smaller front ring, but don't want to feel compromised when I've always ran a larger chainring.

165's = more rpm for short legs. Ideal if you like to pedal out of corners in lowish gears.

you only run a larger ring because of the leverage ....

short cranks with smaller ring .... will work out the same gear if you do the sums correctly ....

a gear is subjective to the input force , if the input force is on a longer lever you can run a bigger ring slower ....

but if the input force is on a short lever you can spin a smaller ring faster ....

also remember if you use shorter cranks to drop your saddles

my next xc bike is getting 180s . Ive done plenty reading on the subject and with the length of my thigh i should really be running 185s ...but they dont exist ;)

Ive run 180s for a while now. Only 6ft but the liking started on my racebmx with profiles...then fitted thm to a street bike for a laugh and then managed to find a set of turbines for xc :D

Now im buggerd as i'd like some more 180s but cant find anythin half decent

middleburn are what im getting

mines are going on a 29er so i have all the ground clearance i could want

on one scandAL for the win ...unless someone wants to give me something similar

ran 175 middleburns for an age and am using 170 deore square tapers on the race bike atm and its a very noticable difference when climbing , im a masher , the bigger the gear the harder i push the faster i go ! i just cant get that rhythum going on the 170s , its all wrong (using same size rings you see)

kool so doesnt sound like there are many bad points really unless your really tall. think i made the right choice, will definately help with ground clearance. marginally lighter too i guess ;)

hey man i run my cranks to the same size as my ankle to knee so measure it up and go ride some sick tracks ps if its to short and u do a nasty drop ure legs will break

erm ok so your saying most people should be running at least 300mm crank arms? and why am i going to break my legs?!?!

English please? Ankle to knee....some large cranks there.  ;D

You could buy some of those razor like pedals to give you a little more clearance. There was a topic a while ago, but i cant find it...

Go 165 i say.

Rich

yeh got some 165s Atlas FRs. cant really notice the difference which is a good thing as everything likes the same as im used to but i know the clearance is alot better now!

Tbh you wont actually know the difference. maybe for 5 minutes as you first use them. but Ive used 3 different lengths of cranks and i never noticed any difference to them. or maybe I'm just weird maybe you might feel a difference?