Hi guys,
My bottom bracket is making some squeaky noises and it needs to be serviced, if possible, or changed for a new one.
The problem is that this is an old bike (25 years old or more) and I don't know which BB to buy.
Or I might take it to a shop but I'd like to know what kind of BB I have.
Which tool can be used to unscrew this?
Don't bother about the cable, I already changed it.
Thanks in advance
by njsilva84
6 Comments
that just looks like a Shimano bottom bracket. you need a special tool to pull it out, that will cost at least half the price of a new bottom bracket. unless you’re going to do this regularly, you may as well just have your local bike shop to it. you’ll need to have them figure out which model you need anyway.
BBT-22 or equivalent 20 spline tool should take that out. It appears to be a sealed cartridge bottom bracket. On high end ones you replace the bearing cartridge. On basic ones like this, you replace the whole bottom bracket.
Your bike likely uses BSA threading, so you’ll want that. Post the model of the bicycle for confirmation.
Besides that just match the spindle length. If you can’t get the exact length, a few mm extra is better than a few mm less in most cases. But you shouldn’t have an issue finding the right thing.
Shimano UN-300 is a no frills but high quality, and inexpensive part and would be my recommendation.
ETA: forgot to mention BB shell width! Measure with the calipers the part of the frame the bottom bracket goes in. It’s probably 68mm as that’s the most common, but you’ll want to confirm it isn’t 73mm before buying.
BSA (English) threading. 68mm frame width x 107mm spindle. JIS taper.
The tool you need is a cartridge bottom bracket tool. They are specialized, but not too expensive. The Drive side (where the chain is) is reverse-threaded. (Righty-Loosey/Lefty-Tighty)
When you install a new bottom bracket, bottom out the drive side threads first, then install the non-drive side cup.
It’s a square taper bottom bracket for the
BSA standard which usually is 73mm or 68mm wide for small bikes, and 84mm for some older downhill bikes.
All kids of bike suse BSA it sover 100 years old standard.
BSA stands for Birmingham Small Arms Company.
They used to make bicycles, motorcycles.
Many high end bikes use it.
Many low end cheap bike suse this standard.
So if sticking with this standard it makes swapping over parts easy.
You can upgrade to much lighter external cartridge bearing bottom bracket and cranks with hallow aluminium crank. Make sure the axle diameter matches the bottom racket inner diameter.
The common are 24, 30mm, but then there’s Sram dub which is slightly below 30mm.
There’s no standard.
Looks like a cartridge BB and if so you service it by buying a new one
Please change the frayed cable ASAP before it snaps.