Ive got RPM cranks and formula hubs and i think when the bike got built the wrong bottom bracket spindle length was used.

Does anyone know the correct length for this set up? or can anyone direct me to where i can find out?

I've searched and didn't find any answer.
thanks

I guess RPMs are the same as Bulletproof.With bulletproofs you'll get a 45mm chainline with a sugino 103 and the ring on the outside.To get 42mm you'll either have to put the ring on the inside and use a 107ish bb or use a 3 piece bb with a spindle that gives you 48mm from center to end(possibly the short end of a assymetrical spindle).

RPMs are not the same as bulletproof, so OP, you can go ahead and disregard Build Your Own's advice.

OP, why do you thin the wrong spindle length was used? did you measure the chainline? hold a ruler against the middle of the seat tube or down tube and measure the distance to the middle of the chainring teeth. what do you get?

Sorry,that was based on the fact that bulletproof are rebranded RPM and there was a discussion on rebranded rpm here a while back.

interesting. they look different and have different BCDs. go figure.

The reason i ask is because it looks as though the chain line is out, also black coating on the teeth is wearing off (not sure if this is normal or not) and its also making a bit of noise.

Just measured and i'm getting 25mm with the ring on the outside.

from the MIDDLE of the seat tube to the middle of the teeth. it should be between 40 and 45 millimeters.

bugger sorry meant 45mm, late uni nights are getting to me.

sounds like you could use a spindle that's 4mm shorter. you could also put the chainring on the inside of the spider.

I was talking about the 110 bcd one that's identical.The one that comes up alot when searching for cheap cranks.

Get a 103 BB (Tange Seiki makes one for 20ish)