I'm new to repairs, so please let me pick your brains for a moment...
I ride a 68 Raleigh super course, fixed on an old cottered crank set in miserable but fun Chicago winter. It's time for a new crank set. Where do I begin? How do I know what size I am looking for? Size of BB? Also, any recommendations on a decent inexpensive set, 46t?
I'd begin by using the Park Tools website and Sheldon Brown's website to read over how to remove a cottered crankset. Sheldon should also have the information you need on your particular bike.
Working Bikes looks to be Chicago's bike cooperative. If you don't have tools, they're probably a good resource to get through this repair... and they may have suitable used cranksets available.
BEHOLD! THE MANTICORE!
you have an English threaded 68mm bottom bracket. you probable want a 108mm spindle length. a sealed cartridge bottom bracket can be purchased new for about $15, or used at a coop for a couple bucks. Wheel and sprocket has new Origin 8 46t cranksets on ebay for about $40 usually with free shipping, and they would get to you quickly being in the Milwaukee area, or check out the ad for eighthinch.com here on BF, as that is wheel and sprockets fixed gear division.
Actually there is a pretty good chance you have an obsolete Raleigh threaded BB shell (26tpi instead of 24tpi). Your choices for replacements are Phil Wood ($$$), or hope the current one is in good shape. I'd look for a vintage friendly LBS, and see if they can get you a new pedal spindle that will allow you to use a more modern crank. If it is "time for a new crank" for aesthetic reasons or the like, you might find it not to be worth your while unless you can find a modern spindle pretty easily. The fine people in C&V will know more than me, and its possible (I'd say unlikely) that you have a normal English threaded BB and this advice is meaningless. Just be aware, this could easily end up being a more expensive process than you hope, and not all shops are going to be able to help you with it.
I've gone through the process of upgrading an old cottered crank bike to a more modern drive train. Although I'm immensely pleased with the result, at the end of the day it was an expensive project.
Originally Posted by maygan21
If I had it to do over again, I'd first try to fix the original problem that made me want to replace the crank set. One of the crank arms started to wobble because the cotter pin came loose. I could have fixed that problem by scrounging for a new right sized cotter pin and replacing it -- I think Sheldon Brown's web pages explain exactly how to do it. The old pin flies right out if you strike it confidently enough the right way with a hammer. I assume it could be replaced just as easily by following his instructions. The problem is that few bike shops these days have any experience at all with cottered cranks and they don't stock the 50 cent pin you'd need. I'm sure though that there are vintage bike experts here on BF who could talk you through the repair process, if that's what you decide to do.
I have one or two of those pins left over from a '73 or '74 Raleigh that got stolen in '94. I used a block of wood to remove old pins, I'd keep the old nut on the end of the bolt part. Sometimes the pin got chewed up when it got loose. The bottom bracket was pretty simple. The old Raleighs came with a tool bag that attached to the seat and they had the tools you needed to remove the bottom bracket. You had to get in there and clean out the bearing races every once in a while. I still have one of the tools but not the one for adjusting the bearing race. I'd try to use the original stuff, the crank arm on that old bike was a very nice chrome, something you'd want to hang on your wall just to look at. Well maybe not everyone would get off on nice chrome parts hanging on their walls.
Originally Posted by Platy
Thanks for the responses.
I had to change one of my pins a couple months ago and I'm not sure it's the correct size. The cranks feel wobbly, I'm sure this is a problem that can be fixed but I'd prefer a new set all together considering my last pin just snapped off and my spider nuts (if you will) keep coming loose. I have reffered to Sheldon's site many times but never found what size bb I should get.
Thanks for your replies, I have reffered to Sheldon's site many times but never found anything on sizing bb's, maybe I missed it. I do feel it's time for a new replacement since a pin snapped on me and the spider nuts(if you will) keep coming loose. The whole set is wobbly, which can be fixed but I think ole betsy needs to retire.
I predict you'll wind up taking the bike to a shop to get one of the old bottom bracket cups removed. If it's stuck (and it probably is) you'll need at the minimum a big vise and a ton of confidence to get the cup out. Anyway, that's a good time to try to fit a replacement BB cartridge. I bet most bike shops have plenty of discarded cartridges that you could try. Sheldon's site has somewhere a table of what happens when you try to put any size of cartridge in any other kind of BB - it either fits, falls through, threads backwards, is too big, etc. That will help you deduce what kind of BB you have.
Originally Posted by maygan21
(go to "Bottom Bracket" and start reading)
Cartridges come in different lengths too, depending on whether you're going to use a double or a triple crank. Then of course your front derailleur won't be compatible with the crank and you'll need adapters because your tubes are too skinny, and so on and so on.
Last edited by Platy; 01-09-09 at 04:28 PM.
Reason: Found the link
Have you posted this in Classic and Vintage? There are a lot of people there who will know.
For now... if your bike was made at the Carlton plant, you probably have English threads, 24 tpi; in which case you have a lot of options for upgrading. But if your bike was made at the Nottingham plant, you probably have Raleigh threads, 26tpi, and your options are very limited. Those options have been discussed ad infinitum in the folding bikes forum; the ever-popular Raleigh Twenty has that size threads and a lot of people have upgraded those BB's.
I don't know where yours was made; the Super Course had 531 main tubes and, I think, a "Carlton" decal on the seat tube; but I'm not sure that's definitive.