Of Cottered Cranks and Fixed Gears
 

I've been searching for an answer to this all morning. Hopefully you guys can help me out.

I recently acquired an old 10-speed from the 70's. It has a good frame for a fixie and I plan on doing the conversion this winter. The issue is, the bike has cottered cranks. An ex-bike mechanic told me that if I use the cottered crank on a fixie, I will risk breaking the chain. This is because cottered cranks are typically off center slightly and this can cause an increase in chain tension. I have been unable to come up with any supporting evidence of this. Is there any truth to this statement?

If so, I should get a square tapered BB and pick up an old square tapered crankset. But how do I know what size BB to get? The bike is a Prince Deluxe and says "Prince Racer" on one of the frame tubes. I believe the bike was made in Taiwan if that matters.

Cottered cranks are less than ideal if you're applying lots of force to the cranks. There's also the possibility of warping the cranks. I'd say you'll probably be OK if you're not skidding or applying backwards pressure.

However, used cranks and BBs are not difficult to find and are certainly not expensive so I'd personally just get a new crank and BB. Do get a square taper.

The BB is probably English but you should take it to have it measured.

to save on trying to find the right cups just reuse the old cups and go get a new jis or iso tapered spindle from your lbs use the old one to find the right one they should be able to measure it then buy new bearings o fit into the bb grease it and put it together

Thanks for the advice.

Fortunately for me, there is a large bike swap meet in town on Saturday. I should be able to convert to a square tapered setup for less than $10. I can carry my frame and spindle with me and figure out what fits.

I've converted from cottered to tapered with no problems, I probably lucked out when I grabbed an old spindle out of my bb parts box and it was an exact match for size. Have a couple thousand miles on it with no problems so far (minus tightening it up once). Also, some cottered cranks arent *that* bad.

I think millions of single-speed bikes have been made with cottered cranks- not fixed gear, just old single speed bikes. So breaking the chain sounds a bit unreasonable.

I ran cottered cranks on my first conversion for several hundred miles with no probs. Unless you count the 5 lb weight penalty that is.

I'm currently in a similar dilemma, cept I dont want to pay for new cranks for my thrift store conversion that is currently in the works. I've pretty much settled on riding em till they are unrideable or i get the money for an alien bikes crankset.

woot madison bike swap! too bad im not back at school yet :(

I don't really want to spend much on my bike either. The whole reason I'm building this bike is so I have something to commute and ride around town without fear of parts being lifted. But if I can spend less that $50 on all the parts, I'd consider that a great deal for a reliable bike. I'd even be willing to spend $100 on it with gas prices continuously going up.

Ran cottered cranks on one of my fixed bikes for almost three years now, still works fine, ride no brakes. Dont listen to that guy.

my first fixed bike had cottered cranks and i broke the crank within a few minutes. i cant remember what broke exactly, presumably it was the cotter pin.

You were lucky. Don't exaggerate.


The cottered pin on my Raleigh 3-speed had so much play, I could almost use it as a mile counter.

It was pretty scary, as I tend to mash pretty hard up the hills.


If it had been fixed, it would have broken.

there about 5 bucks on amazon new cottered bb it is

If it was faulty to begin with you should have either fixed it or not used them, got nothin to do with luck. If your cranks are **** and broken already and you try and use them on a fixed gear, dont blame the types of cranks just because you're using broken ones. I just took my cottered fixed offroad on the trails today and OMG IT STILL WORKS.

well it seems opinions are basically split on the topic, so I think I'll ride my cottered cranks till they break or I get un-lazy and replace the Bottom bracket, which is the only real problem I'm facing. The process of replacing that sucker is ominous to say the least. Any idea what a local shop might charge to replace the bottom bracket to a non cottered one? There happens to be a very nice bike shop where i live, and I'm sure they would do it, I just dont want it to be too pricey.

I appreciate everyone's input. I think I will see what I can find at the bike swap tomorrow. If I can get a sweet deal on a new/used BB and crankset, I will use that instead of the cottered setup.

I'm not sure what a shop would charge to install a bottom bracket and a crank, but it's a pretty easy job. I can't imagine they would charge more than 50 or 60 to replace a BB on a single speed or fixie. Plus the cost of parts, of course.

my first fg had cottered cranks and i bent the cotter pin so that the prospect of recovering the frame now involves cutting the bb spindle to get the cranks off. get those cottered cranks off before you bend the pins, which you will do.

it is pretty easy to remove a bad pin, just involves a fair amount of force.

i tried for three days and brought it to my lbs, now in fairness, my lbs in new hampshire sucks.

from my 1950's higgins. If you run cottered cranks, run a brake. Don't apply back-pressure. I'm taking out my 1" pitch drivetrain on this bike and throwin on crecord.

http://farm3.static.flickr.com/2061/...58392e7784.jpg

50 or 60 bones, *gasp*
looks like itll be a DIY job.
Now, I think I've figured how to disassemble the bottom bracket, once i get it out do i just screw in the new cartridge bb that will replace it and stick the lock ring back on the non drive side or how does the process work/will i need a special tool?

think about it; before there was square taper, all the old timey track bikes had cottered cranks. its just a matter of installing them right

There's a reason that you don't see cottered cranks anymore. They're an inferior technology. Make the step to 1980's tech and go cotterless!

Basically, yes. Screw in the new cartridge and screw in the non-drive side. Make sure things are nice and tight. Depending on you bottom bracket, you may need a special tool or a spaner to do this properly. Here is a link to a helpful page for replacing a bottom bracket. http://www.parktool.com/repair/readhowto.asp?id=94