Aargh! Chainring touching the chainstay!

Your crank arm do look really a long way off you stays thay would be even more with a 127mm or more axle ;)
 
I have a similar issue with RS2s on a Klein Pulse which should take a 73mm bottom bracket, the UN55 appears only to be available with 127.5 axle in 68mm shell.
Does this matter?
 
without this descending into a technical slanging match, old cranks, wide stays, equals wide axles whether you want it or not.

My Toplines and my old RS-1 needed the 127mm axle on my GT as it had big fat stays and lots of mud clearance. Skinny steel doesnt suffer from this problem so much and you can sometimes even fit narrower axles than OEM.

You could try a compact chainset but if you already have the parts, a new BB is required.

Hopefully its not a 78mm/ 127mm BB as they can be a git to find.
 
My 1990 Alpinestars CromegaDX runs a 127mm bb axle from the factory, on original DX cranks.

I'm with LGF on this one.. :cool:
 
the longer 127 axle would work, as it is the alternative chainline to the 122's for none low profile cranks. Same as early XTand DX and most before it.

I don't know the year of your frame, but if it's anywhere near 1995+ there is a good chance is was designed around smaller rings, to give maximum tyre clearance.
The paint rub before will be from mud and dirt on the rings, similar things happen from tyres in winter.

your chainline though does measure short.
The early standard being ~47.5 (centre of middle ring to...)
 
Fantastic help fellas, thanks.

I thought I'd done well to find a 122.5/73 ti BB, so now the search begins for a lightweight 127/73 - I wouldn't be bothered about the BB being Ti, except this is for a lightweight build!

*sigh*

Although the frame is a 93, I think they all came with compact cranks. Either way, the RS2s need a long axle, so It's probably a mixture of both.

Anyone got a nice light 127/73 BB lying around then? :LOL:
 
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