New member with Trek 950...need help!

[LeePrice]

Hya guys

I'm new to the forum...so hello to everyone!

I've got a bit of a problem and need some quick help. I'm building up a Trek 950 which I think is a 94 model, possible a 95 (it has Tig welding with a sloping top tube).
I've fitted the seat post which is 27.2mm with no problems...however a 28.6mm clamp on the front derailleur is too small!

Can anyone offer any advise?...my parts supplier says it should be a 28.6mm clamp for a 27.2mm seat post (just thinking I need to measure the derailleur and check it is 28.6mm he sent me..but it's dark now).

Does anyone know anything different about the front derailleur sizing?

Many thanks

Lee

 

[Markybeau]

Re:

The derailleur, if Shimano, will normally have the size stamped on it somewhere. Sometimes has a circle with a line through it before the size in mm

 

[retrobikeguy]

Re:

Sure the front mech on these is a 31.8mm from memory.

 

[d8mok]

Re:

It’ll be a 34.9 on I bet. I’ve got a trek here that’s got a 27.2 post and takes a 34.9.

If you need a front mech I’ve got a Deore one , top pull for a fiver plus post

 

[mattr]

Have you actually measured the seat tube OD, 950 of that era is steel from memory, so 28.6 *should* fit. (i had a 1992 Trek 970)
(Might look a bit small, but i've had "correctly" sized band on mechs that have 5mm or more of clear air between the bolt tabs when fitted and tightened to torque!)

 

[ishaw]

Re:

Front mechs generally came in 3 sizes, not always linked to seat post size as frame tubes aren't always straight up and down. My gt rts has a 26.8 seat post but a 31.8 mech clamp for example). If 28.6 doesn't fit, it will be either 31.8 or 34.9 (I'm always getting sizes mixed up but hope I've got it right this time).

 

[LeePrice]

Re:

Thanks everyone for your help and input. I measured the frame this morning as best I can and it looks to be a 31.8mm clamp I need.

All the best

Lee

 

[d8mok]

Re:

Bottom or top pull? I’ve probably got something for sale

 

[LeePrice]

Re: Re:

Bottom or top pull? I’ve probably got something for sale

The one I have at the moment is top pull. Luckily the seller of the original derailleur thinks he has a 31.8 replacement and is going to send it free of charge.

I'll bear you in mind of there's a problem though.

Many thanks

Lee