Hi, I need to buy a new seatpost clamp and front mech, can anyone tell me What I measure, is it the diameter or circumference?
Oh, and on the subject of front mechs,what's the difference between the different types, as in top and bottom pull etc?
best bet is to look it up on bike's web site -- could be a few different options. . .
Seatposts are specified by their diameter and length e.g. 31.6 x 400mm
Seatpost are the frames internal diameter.
Font mechs are the outer diameter of the tube its clamping to.
Top and bottom pull refers to where the cable comes from, i.e. if its routed beneath teh bottom bracket its bottom pull. However i think most are for top and bottom now.
Best just post what you are after and what frame you have and someone will tell you
+1 for bland's response, but to add to it, when you're looking at measurements, don't assume that the seat[b]clamp[/b] measurement is the same as the front mech's as seat tubes frequently taper / bulge from top to bottom. Again - just post up what you've got and / or have a look on the manufacturer's website.
Thanks for the help so far guys,I've had a look and it appears to be about 31mm, does that sound about right?
The seat post that fits says 27.2 on it though if that's anything to do with it?
It's a 2010 voodoo wanga frame, and I'm after what size clamp I need and What front mech to buy?
Thanks again
27.2 is the diameter in mm. If you take a rule and measure the diameter across the bottom you will see it is 27mm + a little bit.
Look at a bike shop - eg chain reaction cycles and you will see that seat posts are normally:
27.2mm
30.9mm
31.6mm
There are some other rare sizes and larger ones but these are the most common.
the seat post clamp will be this + the material thickness.
eg on an aluminium frame with a 27.2mm post it is often 31.8mm clamp.
on an aluminium frame with a 30.9 or 31.6mm post it is normally 34.9mm clamp. Clamps also come in common sizes.
For the front deraillieur clamp there is are standard sizes again:
28.9mm
31.8mm
34.9mm
This may or may not be the same as the seat clamp size as some bikes have tubes that taper. Just measure the diameter and see if it is close to one of the above. Most will come with adapters to change the diamter. eg a 34.9mm one will have adapters for one or both of the other smaller sizes. But you can get ones that only fit the smaller sizes (or 31.8 reduced to 28.9 with an adapter).
Top pull - the cable comes from above downwards
Bottom pull - the cable comes up from under the bike
Top/bottom pull - can do either
Conventional - the clamp band is high and the mechanism hangs below
Top swing - the clamp sits just below the mechanism
Choosing one depends on the frame layout - some have bottle cage mounts in the way or the tubes have other features that limit choice. If you can use either than get a conventional type with the high band.
Andyl - thanks, thats explained just about everything! 😀
Doh, just realised that I missed that you'd typed clamp hence my rather crap reply last night.
Apologies