Crank Arm Replacement
 

What is the cheapest way to the crank length?

I purchased a single speed build-up on clearance from the LBS several months ago for general city riding and commuting 10mi roundtrip. It runs a 46/18 set up with a freewheel on the back (FYI-I have no interest in fixed). The crank arm length is 170mm. The gearing is a bit low for me and the obvious and cheapest solution is to throw on a 16t or 17t freewheel. However, as part of my ideal gear search I want to try out 180mm cranks (or even 175mm would be okay). My inseam is 37 inches. I get the debate over crank length, but like most things concerning bikes - you just have to try-out a setup yourself.

I'm kind of noobish in the mechanic department and plan to make the changes myself. The BCD is 130mm and is a 5-bolt square taper bracket. From what I can tell, it will be hard to buy just the arms. I would essentially have to buy a full crankset. I don't mind ponying up for a nice crankset, but hate to do so without trying the crank length first. I would like to throw an ENO freewheel on too, but want to figure out gearing first.

Any wisdom/suggestions on the best to approach this? Change crank arm first? Freewheel second? Chainring third? Or something like that. Is it just trial an error? And yes - I used Sheldon Brown's gear calculator.

130 is the standard shimano bcd, probably the crankset u have already is JIS so "maybe" u dont need to change the BB. What brand is the actual set of cranksets? secondly what bike are we talking about? Some bikes have bended chainstays and 180 mms is a pretty long set of cranks...that i have seen in some cheapo bikes to be a problem.

ALways u can keep the 170 and put a 53 or a 50 shimano road chainring. This will give you more inches per pedaling if that is what are u looking for.

Thanks for the reply. The LBS I bought it from built up a 59cm Salsa Casseroll. I'm pretty certain it has an origin-8 Fixed/ss crankset. And forgive me if I don't know what I'm talking about, but don't road chainrings have ramps which, for a single speed, could throw the chain? In theory at least.

I made a quick look at some of my suppliers and found a 172.5 track crank set (FSA w/144 BCD). Finding a 180 or even a 175 track/single chainring crank will not be easy. The Sugino RD2 comes in a 175mm (130BCD) for $70-$100 (for arms only or approx. $150 for complete set). Origin8 P/P Track crank 175mm (130 BCD)for about $75 is available as well.

Thanks... basically any 180 crank set will do, even a road one but u have to play a little bit maybe to make it work, all depends. Regarding the chainring just put a road one, it will work fine, The ramps are for shifting u are not shifting, a road chain or a track chain will work fine as long as the chain is wider than the cog and the chainring you should be ok.

Looking at the crnkaset u have and assuming you have the matching BB I would try to get the same set of cranks but longer. The issue here as somebody mentioned is that for single speed or track or really rare to see those 180 mms cranksets. But u might be able to find them for a road bike. The chainline will change maybe a little bit but since i dont know what wheelset do you have i cant even take a guess but probably it will work fine.

If i was you i would play with the chainring 1st. Then start planing for longer cranks once u know exactly what u need because we are taking shoots in the dark in here. W/o knowing what u have makes it harder sometimes.

Thanks,

Thanks again.

So what you're saying is, I probably need to replace the entire crankset and not just the crank arms. And even then, 180's are going to be tough to find - at least in a fixed/ss design (that's kind of what I'm running into). Since I'm looking to go cheapest to more expensive, I think I will throw on a 16t or 17t ACS Claws or some other cheap freewheel first. Then maybe get the same crankset in 175mm if I like the gearing. Not ideal, but I don't think I have much choice without the process getting expensive and basically guessing at what would feel good.

I am quite tall and always been on the lookout for longer cranks... occaisionally they show up on EPay.

I also saw Truvative 1.1 in the 180mm length for sale at one of the larger online order houses... speedgoat.com , maybe? But this is, i believe, intended for mtbs so the chainline might not work out.

If you can't find a used or budget crank in your length, most manufacturters only make them in their upper end parts (Dura Ace and Record are available in more lengths); or Profile Racing BMX cranks can be installed (again might be chainline innues), surly MR Whirly, Zinn, or whatever company makes cranks for Zinn.

Thanks for the Speedgoat.com link. The Sugino Messenger Crank Arm Set looks like it would fit perfectly. It maxes out at 175mm, but for $65 bucks at least it will give me a better idea of what a longer crank will feel like.