Well! Lots of 'advice' and some lively debate but it all sort of confirms what I suspected in the first place.
My riding style means I rarely leave the middle ring which is currently a 38T. Only really go to the big 48T to take up the chain slack for rough downhill runs or fast tarmac downhills. I also only use the 28T granny ring occasionally when it gets really steep/technical, most of the time my legs do the talking through a 38x(
32)28 gear!
Doing the numbers has just given me a bit of a shock
. I just counted the teeth on all the cassette sprockets to compare what a 2x9 set up would give in comparison and the shock discovery that I am actually running an11-28 cassette. I should have known because I fitted it but how old skool is that? I'm a monster!!!
A 2x9 set up that would best suit me is a 40/28 chainset and an 11-34 cassette. This gives me a 40/34 gear which is a good bit easier than the 38/28 easiest gear I have when on the middle chainring of my existing gears. It also gives me a 40/11 which lands just between gear 6 and 7 of the 48T chainring range I already have. I think this is a compromise I can accept. I also get a granny ring gear range that will be waaaaaaaaaay more spinney than I am used to but can be a useful 'get out of jail option'.
Now the gear ratios are sorted I just need to decide how to achieve this.
Chainset
- Use existing Truvativ Isoflow Trekking arms with new 40 and 28 (30?) rings and maybe a bash guard in place of the existing 48T
- Shimano XT M785 40/28
Cassette
- Shimano or Sram 9spd 11-34 for HG61/PG950/PG970
Shifters
- XT M770 9spd right hand shifter
- M770 left hand 3spd shifter restricted to only 2 clicks
- M780 left hand selectable 2 or 3 speed
Rear mech
- Existing SLX shadow M662 GS
- New XT M772 Shadow
- New XT M771 traditional
Front mech
- Existing XT 1990's
- New XT M771 conventional 9spd
Mixed in with all this will be new wheels and disc brakes, either at the same time as the gear upgrade or a phase II once the gears are installed and running well.
What do the wise and knowledgeable CC'rs say?
I am only considering sticking with the existing cranks because this allows me to retain the bombproof UN55 square taper bottom bracket. My experience of HTII hasn't been impressive on my commuter machine although that has just been upgraded from the entry level BB51 model for an XT BB70 one so I can't comment on if that is any better yet?
I would happily run odd shifters to get the selectable 2/3 gear left hand M780 version and an M770 right hand 9spd but can't seem to find the left M780 for sale separately so might end up running the M770 3spd on the left with only 2 cogs?
