Bottom Bracket Sizing

yenkee

Hi,

Silly question so I'll explain the scenario first...

I've inherited a Carrera Vituoso but with bottom bracket problems. I've managed to take the old one out and now need to find a replacement cartridge but I have no idea what size I need.?

The orginal bottom bracket seems to be a semi-sealed cartridge, and only has four letters printed on it "CH-2J". This doesn't bring up anything when searching around the net.

Looking around, it looks like I need to find out two measurements to know whether a replacement will fit, the spindle length and shell size. The first was easy enough, this came to 113mm. the second however seems impossible to find. Looking around the consensus seems to be that a part of it should be either 68 or 73mm.

Would someone be able to explain how I find the shell size, is this the diameter/circumference of the old cartridge? Or diameter/circumference of the hole which it fits into?

Thanks in advance...

nicklouse

òn the bike measure the BB shell. the length not the diameter so 68 or 73mm most likely to be 68mm

have a read of parktools webby for more info.

Berk Bonebonce

Yup, be sure to get one with a 113 axle.

And the second bit ain't as complicated as you would think. Have a look at the table at the end of this document: http://en.wikipedia.org/wiki/Bottom_bracket Your bike probably falls into the first category listed in the table, but there's a chance that it might be of the second type, the Italian type. You can forget the rest of the table - it won't be one of those.

How do you know whether English or Italian? The direction you unscrewed the cups out will tell you - see table. If Italian, both cups would have unscrewed counter-clockwise. Not so if it is English style.

If a BB shell is English style it will be 68 wide, and if it is Italian it will be 70 wide.

yenkee

Thanks, this makes more sense now. I've not been able to measure the second length as the cartridge is a semi-sealed (has exposed BB on the left side).

I've gone for the hunch and brought myself the Shimano BS UN54 Bottom bracket with 68mm shell width.

Any one know what the BS means? Wiggle seems have a lot variety of UN54s, Double, Trple, IT, BS... very confusing :?

nicklouse

link to the confusion as what wiggle type may not what we understand.

but you need a bb with a 113 axle for a 68mm shell with British Standard threads. (or ISO)

http://www.sheldonbrown.com/bbsize.html

for more info.

mikealexander

I've just removed the BB from a Carrera Virtuoso to replace it, searched for "CH-2J" and this thread was the only direct match.

Out of interest, what replacement BB did you go with and any tips as a result?