New BB
 

I thinking of just updating to a cartridge style BB, but i'm a little confused. I currently have cup and loose ball style. Crank is older 600 w/bio-pace.

I know what all the mesurements mean. What I'm worried about is, are all the square tapers the same? It seems that shimano makes like 6 different sealed cart. style BB. How do you know whats works?

thanks

Shiamno uses JIS taper, so that is not an issue unless you are deaaling with track cranks Match threading, shell width on frame( 68 and 73 are english thread, and 70 is Italian) and spindle length.If you you really know what the measurements mean there should be no confusion.

I suggest you visit Sheldon Browns site to get a grounding in Bottom Brackets.

Taking a semi-edjumicated stab at it, I'm gonna go with a 68mm square tapered, either 115 or 118mm in length. But I really don't know the speciifcs of the frame so threading and such is just a guess.

No guessing involved,He can simply measure his spindle and the threading should be on the old BB, assuming he doesn't actually know what it is.

Gee, thanks for the insight. I though I might give the guy a little direction and a couple things to look at. Next time I'll adopt the Sydney dismissing hand wave.

Hard to beat actual measuring. 8 speed 600 used 115 and older ones were 122(and maybe others) which isn't even listed. AFWIW, it's sydney.