1991 Trek BB Shell size

[fedrat]

I've got a '91 Trek 820 Antelope that needs a new BB and I don't know what size to get. I've had a google and not found anything and was hoping someone on here might be able to help.

 

[richierich66]

I have an early nineties alpinestars and that has a 73mm shell so I would assume that yours will be the same.

 

[FluffyChicken]

I have an early nineties alpinestars and that has a 73mm shell so I would assume that yours will be the same.

I would not assume that, most bikes came with 68mm shell width

Trek's I believe are the same and used 68mm for the majority of their bikes.

BUT get your tape measure out and just measure it


As for the length of the axle, then either post up what cranks they are, or a picture, or measure it if you can.
A guesstimate for 1991 and shimano would be ~122.5



EDIT to add,
Trek 820 came with 200GS crankset. which uses on odd size apparently of 121mm length.

 

[fedrat]

Will I need to fit a 121mm or can I get away with a 122.5?

 

[FluffyChicken]

I would think it was fine.

Though if it's not a 200GS chainset (black plastic coated lump of iron, I have an arm I use as a thumping hammer) it may need something different.

Do you have any other plans for the bike, like getting a lighter chainset ?

 

[fedrat]

No real plans at the moment apart from either trying to source a 200GS front shifter or fitting some shifters I obtained from a donor bike found in a hedge.