24T difference does work but...

Manc33

I had a 24-34-46 chainset (worked perfectly, 22T difference) and swapped to a 24-36-48 (24T difference).

What I have noticed is, if that middle chainring didn't have those ramps and pins on it, I don't think it would shift from middle to large chainring. This is only because I am exceeding the max tooth recommendation.

Is this normally the case? On a 22T difference I get a near-instant change from middle to large (34-46T) but when I make that max difference 24T, it takes a bit more of a spin of the pedal, then the chain has to hit the ramp, then it changes.

It works - on a wing and a prayer.

Or what you can do is make the FD cable a tad tighter so you do get a better shift up, but then the middle chainring to biggest sprocket rubs a lot (and sprocket 2 and even 3 a bit).

So its setup now with minimal rubbing and it changes up using the ramp.

Ruddy triples! Can't live with them, can't live without them.

I read somewhere someone was using a triple with a 26T difference and getting away with it, pfffffffffff! They must have some magic front mech or something. :twisted: If going to a 24T difference means you need the ramps to shift up, imagine what 26 difference is like.

cycleclinic

yep exceeding max capaity of the mech can do that to the shifting.

Manc33

thecycleclinic wrote:

yep exceeding max capaity of the mech can do that to the shifting.

I'm not trolling but I noticed the FD is about 2mm-3mm from the chainring, didn't have a bike stand, didn't get right down to see it head on until after a quick test. I reckon getting it the thickness of a fingernail away will fix it. Whats really mad is my chainring sizes setup now matches the 1998 XTR left shifter.

So does that mean the M950 XTR triple front mech would say in the spec PDF it has a 24T max? They made XTR rings that were 24-36-48 is all. :?

desweller

You want a frame that will take smaller wheels mate. Seriously. You're always on the hunt for lower gearing; maybe you need to look at 26" wheels.

cycleclinic

XTR M950 mechs are mostly if not all top pull so your bottom pull cable routing is a problem. A larger capacity FD is the answer and I know there is a bottom pull Shimano Deore DX FD out there. I have one on a old marin MTB with 26T/36/46T chainrings. I haved one of those XTR chainsets on another bike, it's ace.

The point about lower gearing is true though. I think a bit of training is reqired. I hawl myself about on 53/39 and 12-25 cassettes and mostly sit in 53:17MTB- 53:13 even on 10% gradients. Manc you might be somewhere hillier than me but I would just use lower gears that hardly ever see use at the moment.

In fact why not buy an old MTB frame pickup the M950 groupset (cassette, mechs and chainset) including some Dia Compe 987 canti brakes and fit drop bars to it with some old ultegra or DA 8 speed shifters. It would be a bit frankenstien but kind of cool and probably a good ride if you get the right frame size to make drop bars work well.
OLD MTB frame make very good touring frames in reality much better at that than they were at being MTB's if you compare them to a modern XC machine.