Replacing Chainring

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BSA

Senior Member
Location
Sheffield
I have an old 70's BSA road bike. I want to replace the cottered cranks and chainring with new cotterless ones. I then want to fit a modern sealed BB.

I have counted the teeth on my single chainring and it has 46 teeth.

should this fit :
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=270419466776&ssPageName=ADME:X:RTQ:GB:1123

I'm guessing that all 46 teeth chainrings are the same diameter due to the spacing on the chain?

Also I think its a standard 24tpi BB so how do I know what BB to order that will fit the above chainset.


 

4F

Active member of Helmets Are Sh*t Lobby
Location
Suffolk.
For a single chainring standard square taper then a UN54 square taper BB should do the job
http://www.chainreactioncycles.com/Models.aspx?PartnerID=79&ModelID=17473

Probably going to be a 68 (worth measuring accross your BB to double check ie 6.8 cms) and the 68 x 110 should do just the job
 

e-rider

crappy member
Location
South West
Well, some chains are narrower than others eg. old 1/8" (single speed) then 3/32" (5-8 speed) now 9, 10 and 11 speed are three additional sizes each narrower than the previous! That makes 5 different chain widths.

As stated the shell width is probably 68 but getting the correct axle length can be difficult and depends somewhat on the exact cranks that you fit. As already stated, a 110mm is a good place to start.
 
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