Cycling UK Forum

does anyone know if a 9 speed triple front derailleur WILL work correctly and reliably on a 7 speed set up? front rings are 30-40-50, rear is 13-28,
rest of set up is Shimano
apologies to the guys who offered various front mechs I have been away for a few of days and will get back to you!

Too many other things to consider.

Diameter of down tube, braze on or band on?
top or bottom pull
centre line of front triple, ie can the changer go far enough in or out.
Will it clear your chainstay, pretty certain it will with a 50 tooth chainring.
Is your chainring perfectly true as the narrower cage on a 9 speed gives less spare room.
Does the crank on the right side go wide enough to clear the changer.

These are all things that have caused me problems.

28.6mm, bottom pull,band on,chainset true, plenty of clearance.

I'll probably regret saying this but to the best of MY knowledge it should work. I certainly bought a Mega9 Deore changer for use with that chain thickness but didnt actually use it because there was not enough room between the frame and the tyre for its lever arm. I forgot to mention that problem in my list!
You could wait for someone else to back me up on this.

It'll have to be a road triple. The MTB version has too deep an inner cage plate for a 10 tooth middle-outer gap, it'll foul your middle ring.

I am a bit confused dont MTBs still have a 10 tooth gap just with smaller chainrings. eg 22-32-42 or 24-34-44 or 26-36-46 or is that just tourers.
It appears buying that Deore may have been an even bigger mistake than I thought.

The Deore series are designed for a minimum 12 tooth jump, eg 46/34/24.
Believe me, I tried one with a 48/38/26 chainset, it doesn't work unless you set it so high the changing is crap.

Thanks I had missed that, nice to know that it will possibly work if I use 50-38-26, which is what I have on the bike but would have changed to 48-38-26 to suit the MTB style changer.
However that will not happen as long as I can get old fashioned Deore LX's, DX's, XTs etc.

The curve of the plate is best suited to 48 teeth outer or less. I found that 48/36/26 works well with Deore mechs, 48/38/26 needs a road triple. The best I have is a Campag Chorus braze-on mounted on a band-on bracket.