Help with Bottom bracket spacers

[bjellys]

whats the maximum spacer size you can use on a shimano square drive bottom bracket to adjust chainline
I have fitted 2.5 mm spacer but I could do with another 2.0mm so can I put another 2mm spacer on and not compromise the fit of the bottom bracket ,there is plenty of clearance on the chainstays.

 

[FluffyChicken]

Re:

sounds like you have the wrong bottom bracket.

what are you trying to fit into what.

 

[bjellys]

Re:

I have a 1992/93 Raleigh Summit with with Lx triple at the front and 7 speed rear and it does not line up enough on the small front to the small rear and at the moment it has 12mm clearance on the seat stays where the arms pass.

 

[FluffyChicken]

Re:

Small to small (and a few slightly larger) is often a gear you loose, mainly as the chain tension has been lost, especially if you've set it up to be able to run top-top rings.

the only gear you need to worry about is the middle ring being in the correct place. About 47.5 to 50mm from the frame centerline.


But just keep adding them until the drive side cannot stay in or the none drive side cannot be screwed in.
Normally for that age you wouldn't have any spacers, if you needed to add them something is wrong elsewhere. only some late 90s e-type used a spacer.
(assuming Shimano bottom bracket)

M550 or M560 cranks?

 

[bjellys]

Cheers all I have 24 retro bikes and this is the only one I have had this problem with so thanks again for the input.

 

[Scvintage]

Re:

There is easily 8mm difference in bottom bracket size options... you must have a short shaft (left to right length)

107mm-122mm five size options (quick google search probably more)

Example if I tried to put xt cranks on a lx size the xt would hit frame. The offset on back of crank is different

 

[FluffyChicken]

Re: Re:

There is easily 8mm difference in bottom bracket size options... you must have a short shaft (left to right length)

107mm-122mm five size options (quick google search probably more)

Example if I tried to put xt cranks on a lx size the xt would hit frame. The offset on back of crank is different

That's not the problem, it scraping on the middle ring by the sounds of it or not quite enough chain tension and it's jumping a bit.

Reality is live with it, 4.5 mm is a lot to shift a chain line.
I have a few bikes where it catches, often just an annoying little bit.

The other option is chainrings/ring spacers being slightly wrong, or middle ring larger than normal and of course photos of all the other bikes helps.


I'm surprised at how much gap you have, mine tend it have 1.5 to 5mm if lucky unless it modern gear.