Bicycle Mechanics - Bottom Bracket Upgrade

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Ranger Bob
03-16-08, 09:15 AM
Am currently ressurrecting my old Ernie Clements roadbike. Unfortunately, one of the cones has cracked on my bottom bracket due to a stuck ball bearing. The current BB set-up is a Japanese Sakae SR-SC 1.37x24T with a 3U spindle. (Note - According to the Bonthronebikes website, this means the Shell width is 68mm and overall length is 124.5mm. LH length = 32mm. RH Length = 40.5mm. Middle length = 52mm).

I am finding it impossible to source another one of these Bottom Brackets (Cone & Bearing style), so was wondering if anyone could recommend a particular Sealed Unit as a replacement?

nitropowered
03-16-08, 09:46 AM
Its harder and harder to find loose cup/cone style BBs. Best bet is to go to an established LBS and see if they have any used spindles or cups.

But I would recommend getting a replacement sealed unit. They are fairly cheap and require no service once they are installed. Shimano UN26 come in a 122.5 spindle length or 127.5mm (msrp $12), UN54 in 122 or 127 (msrp $24)
Ranger Bob
03-16-08, 01:57 PM
Many thanks for the info. Much appeciated :o

Barabaika
03-16-08, 02:10 PM
As you see, it's an asymmetrical bottom bracket: the crankset side is 8mm longer. Most modern bottom brackets are symmetrical, at least inexpensive ones.

You can try to buy a symmetrical bottom bracket and use spacers to move one side of it. Usually, spacers come in 1mm, 1.5mm and 2mm.

A 127mm bb should work; a 124.5mm bb may work or not.
I had a 3T bb and used an YST 124.5mm bb plus a 2mm spacer as a replacement.

Look here at the bottom for specifications:
http://www.yst-corp.com.tw/new/cartridge_bb01.html
Measure the distance A (between the spindle end and the bb shell) in the picture and make calculations.
For example, for 3U it says
L - 127.5mm, A - 32.48mm

If your A is 35.5mm, then you need a 3mm spacer to move the bb to the right.
I_bRAD
03-16-08, 02:13 PM
Where are you guys looking? old school BBs are easy to come by and cheap.
Are you looking at your local racer boutique, or at your local commuter repair shop?
Bill Kapaun
03-16-08, 06:31 PM
Will this work?
http://www.loosescrews.com/index.cgi?d=single&c=Bottom%20Bracket&sc=Spindles&item_id=SU-3S&id=51243614928

You'd need 3MM of spacers on the DS, but the NDS may be too short???

For cups-
http://www.loosescrews.com/index.cgi?c=Bottom%20Bracket&sc=Cups&id=51243614928