Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  

Go Back   > >

Bicycle Mechanics Broken bottom bracket? Tacoed wheel? If you're having problems with your bicycle, or just need help fixing a flat, drop in here for the latest on bicycle mechanics & bicycle maintenance.

User Tag List

Thread Tools Search this Thread
Old 04-16-12, 07:09 PM   #1
Junior Member
Thread Starter
citymouse's Avatar
Join Date: Mar 2012
Posts: 9
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Swapping cottered bottom bracket.

I'm going to swap out some old cottered cranks for a new set of cranks.

So, I have to remove the cotter cranks, and the bottom bracket.
Then I'll need a new bottom bracket with square tapers and a new crankset with square tapers, and thats it, right?

For the bottom bracket, do I need to measure the width of my frame's bottom bracket shell, or are they more or less universal and thats what the adjuster cups are for?

Thanks very much!
citymouse is offline   Reply With Quote
Old 04-16-12, 08:02 PM   #2
cowboy, steel horse, etc
LesterOfPuppets's Avatar
Join Date: Sep 2008
Location: Rock Springs, WY
Bikes: everywhere
Posts: 29,185
Mentioned: 30 Post(s)
Tagged: 0 Thread(s)
Quoted: 1722 Post(s)
Most important is to take note of which direction you have to turn things when removing the existing BB, in order to determine if Italian or English thread (hopefully not French or other standard). You can measure if you want, I suppose. 68mm= english, 70=italian

Check with new crank manufacturer to determine appropriate BB spindle length, however. I have some Campagnolo doubles that require 102mm and some Shimano triples that like 113, for instance. Wrong size may throw off your chain line.
LesterOfPuppets is offline   Reply With Quote
Old 04-16-12, 09:25 PM   #3
Retro Grouch
onespeedbiker's Avatar
Join Date: Oct 2007
Location: Santa Cruz
Bikes: Yes
Posts: 2,210
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
It best to know the whether the BB is Italian before you go trying to remove it. The difference is with standard ISO or English BB, the drive side cup is reverse thread but an Italian is not (the non-drive side of both are right hand threaded). I'm guessing your BB has been on the bike for a while so you may not be able to tell right away which direction loosens the drive side BB. If you can measure the BB shell and feel comfortable making a 2mm call go with it. If not, what is the make and model of your bike if you know it and what make of components do you have?
onespeedbiker is offline   Reply With Quote
Old 04-16-12, 10:22 PM   #4
Junior Member
Thread Starter
citymouse's Avatar
Join Date: Mar 2012
Posts: 9
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
So, if I buy a new bottom bracket, will I not be able to use the existing cups that are already there?

I thought I could just take the cups off, insert a new (square taper) spindle piece, then put the bearings/cups back on.
Essentially just turning the ends of the bottom bracket from cottered to square.

As far as the make/model, its a weird old little folding bike thats been repainted (not by me) and I really don't know much about its origins.
Just that its a single speed w/ a coaster brake.

Also, would it be possible to just take a used bottom bracket/crankset off an old 10 speed I've got lying around and just swap that out?

Thanks again for all the info!
citymouse is offline   Reply With Quote
Old 04-16-12, 10:39 PM   #5
Constant tinkerer
FastJake's Avatar
Join Date: May 2010
Location: Madison, Wisconsin
Posts: 7,640
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 23 Post(s)
Yeah you can just ditch the cottered spindle and replace it with an appropriate square taper spindle and crankset (using the original bearing cups.) If you do this, do not bother removing the (driveside) fixed bottom bracket cup. Especially since you don't know which way to turn it.

If you already have a crank and BB to use, try it and see if it fits with the cups you already have in the bike. Otherwise, you will need a new square taper spindle and crankset.

+1 Measuring the BB shell will help. 68mm, 70mm, or 73mm?
FastJake is offline   Reply With Quote
Old 04-16-12, 11:51 PM   #6
Gratuitous glib and snark
ThermionicScott's Avatar
Join Date: Aug 2011
Location: CID
Bikes: 1991 Bianchi Eros, 1964 Armstrong, 1988 Diamondback Ascent, 1988 Bianchi Premio, 1987 Bianchi Sport SX, 1980s Raleigh mixte (hers)
Posts: 15,355
Mentioned: 26 Post(s)
Tagged: 0 Thread(s)
Quoted: 855 Post(s)
Unless you have a really good light, it may a wise idea to go ahead and remove the fixed cup for inspection if the "old" bike hasn't been serviced in a while...
Originally Posted by chandltp View Post
There's no such thing as too far.. just lack of time
RUSA #7498
ThermionicScott is offline   Reply With Quote
Old 04-17-12, 12:10 AM   #7
Senior Member
jyl's Avatar
Join Date: Aug 2006
Location: Portland OR
Bikes: 61 Bianchi Specialissima 71 Peugeot G50 7? P'geot PX10 74 Raleigh GranSport 75 P'geot UO8 78? Raleigh Team Pro 82 P'geot PSV 86 P'geot PX 91 Bridgestone MB0 92 B'stone XO1 97 Rans VRex 92 Cannondale R1000 94 B'stone MB5 97 Vitus 997
Posts: 7,140
Mentioned: 63 Post(s)
Tagged: 0 Thread(s)
Quoted: 140 Post(s)
I just did this - replaced the cottered spindle with a square taper spindle. Took the cups, bearings, and old spindle to the bike coop and looked through their box of old spindles. Cost $8.

Now, I did that because the bike had a French thread bottom bracket and a cartridge BB for that thread is $50 + shipping. If I had standard English threads and thus the option of a cheap standard cartridge BB, I'd do that instead.
jyl is offline   Reply With Quote
Old 04-17-12, 11:00 AM   #8
Senior Member
Join Date: Oct 2009
Location: England, currently dividing my time between university in Guildford and home just outside Reading
Bikes: Too many to list here!
Posts: 1,921
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Just checking, it's not a Raleigh is it? If it is, there's a chance the BB thread will be Raleigh standard rather than english standard (26 t.p.i. rather than 24)
Airburst is offline   Reply With Quote
Old 04-17-12, 11:55 AM   #9
Senior Member
zukahn1's Avatar
Join Date: Oct 2011
Location: Fairplay Co
Bikes: Current 79 Nishiki Custum Sport, Jeunet 620, notable previous bikes P.K. Ripper loop tail, Kawahara Laser Lite, Paramount Track full chrome, Raliegh Internatioanl, Motobecan Super Mirage. 59 Crown royak 3 speed
Posts: 6,596
Mentioned: 10 Post(s)
Tagged: 1 Thread(s)
Quoted: 162 Post(s)
If this helps when changing out cottered old crank spindel for a newer square type it seems better to use new loose ball bearings rather than raced while a little more tedious it just seems to work better.
zukahn1 is offline   Reply With Quote
Old 04-17-12, 05:47 PM   #10
Senior Member
Join Date: Aug 2005
Location: Pittsburgh, PA
Bikes: '''96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '12 Surly Pacer, All are 3x8,9 or 10. It is hilly around here!
Posts: 30,138
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 593 Post(s)
Since no one has asked so far, I will. What's the make, model and approximate age of the bike? Is there anything engraved on the current bottom bracket cups that might tell us what it is?
HillRider is offline   Reply With Quote

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT -6. The time now is 10:34 PM.

  • Ask a Question
    get answers from real people!
Click to start entering your question.