It’s a great bike with one annoying thing I can’t seem to fix - the rear gears keep jumping whist riding.
For reference, the crankset is FSA Omega Modular AGX+, 32/48
The cassette is Shimano CS-HG710, 12-speed, 11x36
The chain is KMC X12L-1
Things I have checked or had a mechanic check that all seem fine
chain stretch
Cable tension
hanger alignment
I’ve reindexed using the barrel adjuster while the bike is up in the bike stand and the gears seem fine but inevitably out on the road the gears start jumping.
The direction of the jump is from smaller to larger cog and back again.
OK, serious answer is that your cassette may be worn. You could try a new Shimano chain, but since KMC makes most of Shimano’s chains, I kinda doubt that is it.
The fact that it shifts OK in the stand but jumps under load indicates something is worn.
… I had an alloy Cx bike that would ‘ghost shift’ if I put down high power in a hard gear as the Bb would flex relative to the rear wheel and pull /ease the cable tension with each pedal stroke
Cool. So when you tighten up the thru-axle (only in the long setting), it can pull the mech hanger out of alignment. Terrible, terrible design.
Anyway, according to Giant you have to loosen the hanger (the hex bolt), put the wheel in, tighten the thru axle back up, then tighten the hanger screw back up. Completely backward design, but it should work.
Of course it could be something else, but this is definitely worth checking - it was the only thing that sorted mine. Good luck!
I had a long running battle with my LBS about the crap shifting the wonky hanger in the long position produced and eventually got them to investigate it - and that was Giant’s official response / resolution.
Still not happy about it TBH, but it does seems to work.
that’s crazy! Will give it a try. Where did you come by that info?!?!?