never replaced a bottom bracket...

pondweed

Old School Hero
I've got a 68mm frame width, and cranks are biopace triple shimano on the Touristique.

How do I decide the spec for buying a spare BB, and what quality is adequate enough not to go above? I've just bought a (sale) stronglight cassette headset to replace the 20 yr old original, so makes sense to do the BB too, or have it waiting...

thanks
 
Re:

This is a fairly clear set of instructions for replacing a cartridge BB with square taper:

http://www.parktool.com/blog/repair-hel ... ridge-type

68mm is almost certainly English threaded.

A triple crank probably needs an 118mm spindle but of course you can just measure the old one to check.

Quality wise, the standard Shimano cartridge BBs that you can find in any decent bike shop should be OK, they are fairly reliable. If you wanted a better quality one than that you'd probably have to search Ebay for an NOS one. Bespoke square taper BBs like White industries, Royce or Phil Wood are supposed to be nice if you have money to throw around.
 
Re:

Great. Not actually having my cranks off yet, 118 seems about right.

Shimano it is then. From a quick web search, it seems there is a backlash against some of fancy stuff (on other forums) just because the basic design is so good. Amazing you can pay a tenner for something so crucial.

Just got to buy a lock-ring spanner and a crank puller (anything else?)... off to see what Hong Kong has to offer...

wow - THAT'S what that bit of my tiny raleigh bike multi-spanner does! Looks like I'd need to use a hammer though as not enough purchase?
 
You need a BB tool to remove the old BB if it's a cartridge type. Probably cost about 10 quid. You should only need a lock ring spanner if the old BB is a cup-and-cone type.
 
Bolt on cheap tools using a crank bolt. This stops them slipping. Remember the right hand side has a left hand thread. It may take a LOT of force.
 
hamster":22qk5as7 said:
Bolt on cheap tools using a crank bolt. This stops them slipping. Remember the right hand side has a left hand thread. It may take a LOT of force.
and if it's the old type with separate cups, the spanner flats on the fixed (right hand) cup will only be thin, so may be difficult to get a good grip with a spanner. If so, use a vice with the frame held horizontally.
 
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