Bottom Bracket Rebuild

[blacknell]

Hi, all. I'm trying to figure out if I should go ahead and learn how to do a BB rebuild, or if I should send it to the shop and add "Learn BB rebuild" to my ever growing "learn how" list for the future.

It's my primary bike that needs it, and it is important to me that it is done right. I really have no idea if this one of those jobs that is surprisingly easy, or overly frustrating. I've got Zinn's maintenance book, so I'm sure I'll have the right instructions, and I don't mind investing in a specialized tool or two (five bikes in the garage, at the moment). But I guess I'm just looking for thoughts from folks who already do this for themselves.

[fausto]

what type of BB do you have? Most of the more recent ones don't allow you to do much service, other than replace. If it's an open cub/cone deal by all means learn to do it yourself. If it's sealed, but a seperate BB, nothing to do but replace. If it's external, you aren't supposed to but enduro (at least one other) sell a tool that lets you replace the bearings and seals.

[walsh]

If your primary bike is remotely modern, then it probably has a cartridge-type bottom bracket. If your bearings are worn out, then it's very simple in concept: you thread out the old bottom bracket, you thread in the new one, and you're done. (A BB that lets you actually remove, clean, and repack the bearings is most likely to be found on a bike 10+ years old, or a beach cruiser.) When replacing your BB, you need to know the length of your spindle, and the length(side-to-side) of your frame's BB shell. And of course, make sure the BB spindle fits your crank arms (e.g. square-taper, Shimano Octalink spline, ISIS spine . . .)
Zinn will give you details.

The caveat is that cartridge bottom brackets are designed to be self-tightening, and by the time you wear one out, it can be a serious muscle job to remove it. When approaching a BB that hasn't regularly been removed to clean and lube the threads, I would want to have:

- a really sturdy workstand
- a 3-4' cheater bar for leverage
- a hefty hammer (to pound on the cheater bar)
- a propane torch (gently heat the BB shell, the metals expand and different rates, breaking the surface bond between BB/shell)
- penetrating oil (Liquid wrench, for extreme cases

I've used a C-clamp to clamp the BB tool to the bottom bracket (clamp outside of the tool to the opposite end of the spindle) to prevent the tool from stripping the splines.

Good luck!

- J

[drevil]

Hi, all. I'm trying to figure out if I should go ahead and learn how to do a BB rebuild, or if I should send it to the shop and add "Learn BB rebuild" to my ever growing "learn how" list for the future.

It's my primary bike that needs it, and it is important to me that it is done right. I really have no idea if this one of those jobs that is surprisingly easy, or overly frustrating. I've got Zinn's maintenance book, so I'm sure I'll have the right instructions, and I don't mind investing in a specialized tool or two (five bikes in the garage, at the moment). But I guess I'm just looking for thoughts from folks who already do this for themselves.
If you have a hollow spindle on a cartridge bottom bracket, definitely save yourself from frustration and use a rear quick release skewer to hold the tool to the BB:

http://www.parktool.com/images_inc/repair_help/bbtskewer.jpg

You'll save yourself from crushed knuckles and stripped splines. (More from Park (http://www.parktool.com/repair/readhowto.asp?id=94))

[walsh]

definitely save yourself from frustration and use a rear quick release skewer to hold the tool to the BB . . . You'll save yourself from crushed knuckles and stripped splines.

Brilliant!
Ricky, I owe you a beer. Original or not, this tip will make my life better.

[blacknell]

Thanks, all, for the advice. Buying the park tools tomorrow and will have a go at it. If I learn anything useful I'll drop a note back here.