Bottom bracket shell HELP Allin Stan Butler Special

[JeremyA]

Hi everyone in Retrobike land. I need your help and experience. I am starting on my journey to restore a 1970 Allin Stan Butler Special 531 road bike.I will be riding this on the 2026 Eroica in Italy (hopefully) I have now almost fully stripped the frame and have discovered that the BB shell is 65.7mm wide. It has an English thread. There was a Williams steel chainset and cottered axle in place which I removed.





I am planning on fitting Campagnolo NR chainset, I tried to test fit the traditional Campagnolo BB and of course was unable to wind the adjustable cup far in enough to seat the bearings. I don't know what to do next. From some reading online I gather that narrower BB shells were made possibly for TT bikes to optimise the chainline. I now know that I cannot use a shimano sealed unit BB as the Japanese taper is not ISO. I was thinking that a square taper Campagnolo sealed BB might work.

my options?
fit a Campagnolo sealed BB?
Modify the BB shell?
get a different frame?

hopefully someone out there knows what to do

Thanks in advance

Jeremy

 

[SteelNipple]

Maybe I did not quite understand what you meant by "unable to wind the adjustable cup far in enough to seat the bearings" as how I see it this would only be a problem with a shorter spindle on a wider BB e.g. 68mm spindle on a 74mm BB shell.
Have you thought about adding 1mm spacers on both sides between the frame and BB cups to make it 67.7mm wide?

 

[JeremyA]

Thanks. yes I can see what you are saying. perhaps I need to trey fitting it again. where would I get BB spacers from?

 

[SteelNipple]

Thanks. yes I can see what you are saying. perhaps I need to trey fitting it again. where would I get BB spacers from?

Google "Bottom bracket spacer bsa english iso" the inner diameter should be 1.380"