Hello all,
I've fitted a Shimano 26x38T double chainset and a 2x10 front mech. When i have the front mech set to the 26t ring my chain scrapes along front mech (at the rear) in the smaller cassette cogs.
I can't position the mech any lower as the teeth from the larger ring hit it. As it is, teeth profile match the sticker supplied on the mech for mounting. Shifting up/down is fine.
I've built loads of bikes so a little confused. Any advise, am i doing something obviously wrong here?
It could be the seat tube angle is too steep. If its a full suss does it do it when sagged and being ridden?
Are you using an older 3 speed shifter? (10 speed era shifter but not a new one with a 2sp / 3spd adjuster screw).
If using one of those, I found it had to be set up using position 2 and 3 on the shifter not 1 and 2 like you'd first expect. Unfortunately, this also means an extra press of the shifter by mistake (dropping it to old granny ring position) means that the cable goes slack and outer can jump out of cable stops. But it was the only way to make it work - cable pull was all wrong using 1 / 2 = old granny / middle position.
p.s. This was on my wife's bike - she rides most stuff middle / big ring anyway so hated the new ratio setup with 11:36 cassette - ended up stripping it all off after just one ride 🙁
A double setup with 30:40 rings would have suited her much better.
If using one of those, I found it had to be set up using position 2 and 3 on the shifter not 1 and 2 like you'd first expect.
This wont matter, the mech will still be in the same place over the rings.
binno - it could be that your mech is not suited to your choice of rings, as they can come in different sizes for different ring combo's. Also worth noting that you can (apparently) get different mechs for different seat-tube angles. Ive never held one in my hand but have read others solving issues by changing mech type along those lines.
Good luck, post up you mech/chainsets model numbers and some pics if you still need help, sure someone will do some digging for you.
Thanks everyone, still no joy.
Santa Cruz Tallboy Frame
Shimano 24x38T XT Cranks
Shimano XT Shifters.
Shimano XT M786 Conventional 2x10 Front Mech
Shimano 11x36T Rear Cassette
Within the Mech specs it says: "44-38 tooth outer ring compatible, total capacity 14 teeth". What's with the 14 teeth??
All current 2013 gear.
What's with the 14 teeth??
This is the 'capacity' of the mech, ie the maximum difference between your big and granny ring. As you have a 26/38 your difference is 12, so within the capacity. In fact I use the same mech with a 24/38 and I get the chain rubbing on the bottom of the cage when in the small cogs of the cassette, but only in the workstand. When riding the rear suspension sag lifts the chain up enough to clear the cage. Have you only looked at it on the workstand so far - if so try going for a ride and I think you'll find it doesn't rub in practice...
Hi Perthmtb,
Yes work stand only. I thought something was up and sought advice. Experience has told me that patience and asking for help sometimes is better than diving in and breaking things. Fingers crossed, i think you're right. Thanks for explaining the 14 tooth thing to me, makes a lot of sense now!
😉