Derailleur | Everything Cycling

Posts Tagged ‘derailleur’

Derailleur Top

Monday, May 3rd, 2010

Derailleur Top
What type of front derailleur can I fit? ?

I am upgrading the gearing/drive on my 2007 Kona Fire Mountain with a Shimano XT M770 rear derailleur, XT M770 cassette & chain, dual control shifters etc, but am not sure which type of M770 front derailluer to buy, there seems to be a couple of different types which are the ‘E Type BB mount’ and the ‘Top swing’ models, does it matter which one of these I go for?
Cheers.

Front derailleurs can be tricky because you have to choose the right clamp diameter, swing type, and cable pull. Fortunately, your bike will take several different front derailleurs…..and fortunately, many derailleurs now are made with built-in adaptability.

Your bike has top-routed cable which goes down to the derailleur, so make sure you get one that uses top-pull. Most of them nowadays have multi-clamp designs that will do either top- or bottom- pull….just be sure yours will do top (most do, but there are still some dedicated-pull models out there).

As far as swing, you can use either one on your bike. Some frame/suspension designs require that you use bottom-swing so that you don’t have clearance issues with the linkages or tubing, but yours is the simple plain-jane frame design so you can pick either one.

E-type derailleurs aren’t common…mainly used on special frame design full-suspension bikes. You could use one on your bike if you wanted to, but you’d have to be sure that the bottom bracket was compatible for an e-type, too.

Clamp size is the other issue….where the derailleur mounts to the frame. Most of them nowadays are sized for the larger diameter and come with reducer bushings for use on smaller tubes. If the derailleur doesn’t come with them, you can buy them for a couple bucks at a shop (or get them free sometimes). If you buy a single-size clamp model, be sure it’s the right one for your frame.

It’s easier to see how these derailleurs are different if you have a few of each in hand to look at and manipulate….sounds complex and confusing but it isn’t really. Hope this helps you out some….enjoy the new drivetrain. )