Changing a compact double for a triple - questions

[Alembicbassman]

I'm currently using a 50/36 compact double on my Hybrid with an 11-28 cassette.

I'm thinking of swapping it for a Shimano M411 Alivio triple http://www.parker-international.co.uk/9316/Shimano-Alivio-M411-MTB-Chainset.html

48/38/28 chainset using an M410 Alivio triple front mech http://www.parker-international.co.uk/11485/Shimano-Alivio-M412-Top-Swing-Hybrid-Front-Mech.html

My handlebar shifters are SRAM X4

The Rear mech is SRAM X4 long cage

The front mech is Shimano Nexave (will need to change)

The front rapid fire shifter has an optical gear indicator that currently bypasses the middle arrow when shifting to the big ring, i.e it reads 1 then 3 as I am currently running a double.

I assume when I fit the new front mech I will be able to use all three positions

 

[RecordAceFromNew]

I am not sure if you need to buy a new front mech if it is not broken. If your Nexave is a T301 it is designed to run triples of 48/38/28 (i.e. FC-M191).

What you might also want to think about if you want to change your chainset is chainline and bottom bracket. If the bottom bracket doesn't need changing it is worthwhile finding out what it is (either by deduction from chainset spec and chainline measurement, or dismantle and measure), and perhaps selecting a new chainset that has the same spindle standard as while delivering a reasonable chainline with the existing bb. The spec for the Alivio chainset you are thinking about is here.

I don't see why there should be any problem using the existing shifter.

 

[Alembicbassman]

Sheldon Brown's gear calculator works out that I will have just 2 extra easier gears, so I think I will stick with the compact.

 

[alecstilleyedye]

next time you run out of gears on a climb, remember those two.

you should also get bigger gears too.

 

[Alembicbassman]

I could of course just put a 11-32 or 34 cassette instead of the 11-28.

 

[alecstilleyedye]

I could of course just put a 11-32 or 34 cassette instead of the 11-28.

you'll need a long-armed rear mech too...

the other advantge of a triple is the wide choice of ratios that eliminates the gap between large and small rings