New crank and bottom bracket

[suffolksky]

Hello there,
I'm looking to upgrade the gear set on my 80's Dawes Galaxy. I've found a tiagra gear set that i'm happy with and it comes with a matching bottom bracket. Will the bottom bracket fit my frame? If they're not universal, how can i tell which will?
Thanks for any advice
(i think i've already got my head around the rest of the gear set, it's just the bottom bracket i'm concerned about)

 

[non-fixie]

The easiest way to check is to compare the markings on the old BB with the Tiagra one. I would expect the old one to read 1.37 x 24, which is British or ISO. In that case the shell width will be 68mm.

For more information on BB measurements, check Sheldon Brown's crib sheet: https://www.sheldonbrown.com/cribsheet- ... ckets.html

And no, they're not universal.

 

[ScillySuffolk]

The Dawes will have a British threaded bottom bracket shell.

Provided the Shimano BB is also British (and not Italian) threaded, then yes it will fit.

Don't forget that a British threaded drive side (right-hand side) shell/BB has a left-hand thread!