Replacing bottom bracket

[jorgemartin]

Hello!
I have a Shimano BB Square Taper that I want to replace. I've looked online and there seem to be different options:
- 68-110 mm
- 68-113 mm
- 68-122 mm
-73-110 mm
-73-113
How can I find out which one I need? Do I need to get the BB out?
Cheers

 

[Gerry Attrick]

No. The first number (68 or 73) refers to the width of the BB shell. That is the cylinder attached to the frame inside which the BB resides.
The second number refers to the length of the BB spindle. You may need to remove your cranks, but having done so you can measure both components.

 

[lowrider73]

I've just replaced a bottom bracket after 50,000 miles of use, it was starting loosen a bit. I just took the bottom bracket out using the crank and bb tools. Took the sealed unit to LBS and measured it up against a new one. Now fitted. It will say on the sealed unit or should do, the size of unit.

 

[jorgemartin]

50,000 miles of use??? Mine is still okay after 5 years of daily commute in London but now I'm taking the bike on tour and thought that it might be a good idea to replace it just in case.

 

[lowrider73]

5 years of use, depends on the wear and tear. I've just replaced my bb, chain, crank-set, cassette and brakes. Cost £93 in total, well worth it.

 

[Jonathing]

How on earth do you get 50,000 miles out of a bottom bracket!? I find mine knocking and clattering after about 4,000 miles.

 

[Cheule]

Surely he means 5,000.

 

[byegad]

I got under 5000 from my Shimano external BB an so far 6000 from my Campag internal BB both on recumbent trikes. My Club Tour did 10000 miles or so commuting without any sign of wear on the Deore BB. I'd believe 50000 from a well treated and serviced internal BB.

 

[heretic]

The UN72 on my touring bike has done around 12,500 miles and shows no sign of any problems. I'd be disappointed if it doesn't go at least as far again.

 

[albal]

Mine lasted 15 yrs. And a replacement had to be a threadless one as the thread was shot , which gutted me, as these are unknown to me regards mileage.