Finding out the spec of my Chainset?

[Mushroomgodmat]

Hi ,

I have two bikes - one with Ultegra the other with 105. can someone tell me the technique for finding out the spec of them both.

Basically I'm looking to replace one and move components around bikes - I would like to make sure everything's comparable.

Also...I know chainsets come in lots of different sizes (170-175mm 39.53/10-11 speed) and I have no real understanding of what these measurements are!

 

[Graham]

Go on the shimano website - they have lots of 'exploded' diagrams of lots of their parts including the 105 and ultegra ranges which have lots of measurements etc. Alternatively, go to Sheldon's website which has a very useful A-Z section which explains everything you need to know.

 

[PpPete]

170 / 172.5 / 175 (or occasionally larger or smaller) - this is the crank length (centre to centre) In theory 175 is more suitable for taller folks, but most people can't tell the difference. It's usually marked on the inside face of the crank.
10 speed (or whatever) ... relates to number of sprockets on the cassette. The more sprockets, the narrower the chain has to be. Most chainsets cope OK with 8/9/10 speed - don't know about 11 speed.
39.53 .... that's the number of teeth on the chainrings, count 'em. If you make significant changes you might need to add or remove links from your chain.

 

[Smurfy]

All Shimano components have part numbers. For cranks these will be stamped on the back of the cranks. The crank length (centre of BB to centre of pedal hole) will also be stamped on the back of the cranks. Also see the Shimano year/month date codes.

 

[Mushroomgodmat]

cheers chaps!

 

[BimblingBee]

If the kit is roughly the same age then as long as you keep the drivetrain and shifters the same speed ie 8,9 or 10 then you won't go far wrong and it will probably all work fine.