new bottom bracket
02-16-06, 11:50 PM
#1
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new bottom bracket
i need a new bottom bracket. how hard are these to replace? and how do i know what one to get?(i dont have the size)
02-17-06, 12:50 AM
#2
biofueled
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Bottom brackets are measured by shell width and spindle length. A 68 x 113 bottom bracket has a 68mm wide shell and 113mm spindle. The type and length of the spindle will depend on the crankset type and distance required to maintain an ideal chainline.
Removal and installation:
https://www.parktool.com/repair/readhowto.asp?id=94
Chainline:
https://www.sheldonbrown.com/chainline.html
Good luck!
-AJmtnbiker
Removal and installation:
https://www.parktool.com/repair/readhowto.asp?id=94
Chainline:
https://www.sheldonbrown.com/chainline.html
Good luck!
-AJmtnbiker
02-17-06, 08:23 PM
#3
Fortunatissimo
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It is not a very difficult job, but you probably should have enough experience to feel confident.
Do you know how to remove crank arms? If you have a tapered axle, you might need a crank extractor.
There is a good chance that you will need specific tools to open the old bottom bracket and install the new. Some old bbs, like the one I changed two days ago, need a different tool for each side.
Installing a modern cartridge bb is very straight-forward. Be careful that you are threading carefully. Unless you have an Italian bike, you probably have English threading (backwards tightening on the drive side, forward tightening of the left side--opposite when you are removing the old bb).
I believe in using a torque wrench for this job. It makes opening and tightening a lot easier, and you will have the security of knowing that you have closed everything with the proper torque. I got one that works just fine at Kragen auto supply for $13.
Also, a rubber mallet is useful for jumpstarting your wrench. A few years ago, someone in this forum said that he used a 2 x 4 for that purpose. I feel that my bike deserves a softer thud.
Do you know how to remove crank arms? If you have a tapered axle, you might need a crank extractor.
There is a good chance that you will need specific tools to open the old bottom bracket and install the new. Some old bbs, like the one I changed two days ago, need a different tool for each side.
Installing a modern cartridge bb is very straight-forward. Be careful that you are threading carefully. Unless you have an Italian bike, you probably have English threading (backwards tightening on the drive side, forward tightening of the left side--opposite when you are removing the old bb).
I believe in using a torque wrench for this job. It makes opening and tightening a lot easier, and you will have the security of knowing that you have closed everything with the proper torque. I got one that works just fine at Kragen auto supply for $13.
Also, a rubber mallet is useful for jumpstarting your wrench. A few years ago, someone in this forum said that he used a 2 x 4 for that purpose. I feel that my bike deserves a softer thud.
