Shifting issues. Transmission or frame/hanger?
Had my FM936 built up for a few months now, 500miles and enjoyed it for the most part aside from one, rather major grumble.
Since day one I've not been able to get the gears shifting correctly.
Transmission is 12speed XT (cassette, mech, shifter, chain, optislick inner cable that I then upgraded to the polymer, SP41 outer cable).Yes, cable routed correctly. It's always a little out and as 12speed sprockets and chains are so narrow a little out is almost intolerable. It alters during the ride, i.e 1-2-3 good a start of ride but then not good by the end (even if an easy ride so haven't hit it on a rock, etc). It alters depending on the suspension setting (have a nude shock with 3 settings). It alters during suspension compression. It's never quite right.
I wonder if the clutch on the mech is partially to blame for a number of reasons. Firstly, I know the clutch affects shifting, increasing friction at the shifter and think it alters, ever so slightly where the mech rests after a shift, which if true means that because of suspension movement and chain growth the clutch is constantly 'working' and so minutely affecting where the mech sits and given how minute adjustments affect shifting it must be having an impact.
But also wonder if the clutch is actually causing the hanger to bend - as I say when the suspension is compressing causing chain growth it's effectively pulling at the clutch, and so mech, and so mech hanger all the time - it must be having an impact - which is kind of confirmed that when I check the hanger alignment with the tool it's always ever so slight out - is it plausible? Maybe the hangers on these fm936 are a little soft?
I've serviced the clutch, and backed off the tension as much as I dare and it is better but I just dont like the fact I feel like I'm having to compromise on a nice bike!
Like the idea of 1x12 but just seems to sensitive or is it the hanger/frame? - bring back 2 x 10 I say
Any thoughts appreciated.
Derailleur hanger - you know this is the culprit when the shifting degrades in only the middle cogs. If it shifts fine at the ends of cassette, but skips or clunks or is reluctant to shift in the middle three cogs, then it’s likely your hanger.
If it happens all the time, in every gear, and is triggered by the suspension then it’s likely not the hanger. Start by disconnecting the shift cable and setting your limit with the cable disconnected. Go ride the street. There shouldn’t be any clunks or anything no matter what you try to do.
Then, screw the barrel adjust all the way in, back into two full turns. Connect the derailleur cable. Increase tension or decrease tension until you get a smooth shift from smallest cog to second smallest. Listen to the sound. Play with the tension until the noise from the chain is reduced.
Then, work up the cassette and check your upper limit.
If you still have problems then there is something wrong with your cable routing or derailleur or cassette.