BB Questions

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Tom B

Guru
Location
Lancashire
Team;

With the intention of ordering a new BB I have today taken out my ropy old BB with the intention of finding out what size replacement I need. Generally they are stamped on the side no?

I was lead to believe by the specs when i bought it that it would be a Shimano body.

This one has nothing other than rust on the body.

However the end of the bearing there is FSA MR 036 stamped on.

Questions....

Can this be replaced with a standard sealed BB?

Such as
http://www.chainreactioncycles.com/shimano-un55-square-taper-bottom-bracket/rp-prod71369

I understand I need to measure overall spindle length and depth of frame "hole", yup?
 
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Tim Hall

Guest
Location
Crawley
Pretty much, yes. Although added excitement is available in the form of "which square taper do I have?" Shimano tend to be JIS, whilst you can also get ISO taper bottom brackets. The angle of the taper is the same, it's just that the starting dimension is different. If you fit a ISO chainset to an JIS bottom bracket, it will sit further out by a few mm.

(The FSA MR 036 is just the make of the cartridge bearing used in the BB. Following experimentation involving a vice, a club hammer and an old BB,m I discovered a sealed BB is a pair of cartridge bearings squeezed into a bit of steel tube. Sort of.)
 
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Tom B

Tom B

Guru
Location
Lancashire
Pretty much, yes. Although added excitement is available in the form of "which square taper do I have?" Shimano tend to be JIS, whilst you can also get ISO taper bottom brackets. The angle of the taper is the same, it's just that the starting dimension is different. If you fit a ISO chainset to an JIS bottom bracket, it will sit further out by a few mm.

God only knows! I have just tried sitting a crank on this bearing and on another shimano BB-UN52 BBB I have both seem to sit in the same place.
Despite both units being very worn I have to say the Shimano unit (about 15 years old) feels the better made unit and despite haveing slightly more play, still runs better.


(The FSA MR 036 is just the make of the cartridge bearing used in the BB. Following experimentation involving a vice, a club hammer and an old BB,m I discovered a sealed BB is a pair of cartridge bearings squeezed into a bit of steel tube. Sort of.)

That was my plan!

Go on, give us a clue - what bike..??

Ridgeback Flight 01 - 2013 model. I cant seem to find any detailed specs anywhere.
 

lpretro1

Guest
if in doubt measure shell width of frame - will b either 68mm or 73mm and then measure the axle/spindle length of the bb then buy appropriate one
 
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OP
Tom B

Tom B

Guru
Location
Lancashire
That's the one... Or at least it was when I got it!

That's about as detailed as the specs go. I was hoping for a spec sheet with the bearing sizes etc.
Trying to source a spare hanger too!
 
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Tom B

Tom B

Guru
Location
Lancashire
Job done, shouldn't have worried I bought a TH Industries replacement bearing and it was exactly the same down to the FSA markings! So I did the MTB whilst I was at it!

For archive purposes

Ridgeback Flight BB
68mm x 122.5mm

Mongoose Alta
68mm x 112.5mm
 
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