Rear shifting issues when on the smaller chainring

robthehungrymonkey

I've recently put my old groupset (ultegra 6770 di2 10spd) and am having some issues with the rear shifting.

On the big ring, everything is perfect. Indexing is spot on and it is running smooth and quietly. However, on the small ring, it's not the same story. It is a bit louder, and when I'm in the 2nd biggest cog at the back, and under big load (on steep gradients) it slips.

I generally think I'm fairly good mechanically, but have to confess to never needing to do much with rear mechs apart from indexing.

Any help would be greatly appreciated!

redvision

Check the chain isn't worn

diamonddog

As above and check the cassette.

robthehungrymonkey

Thanks for the replies, was out of signal in Suffolk at a triathlon over the past few days with no signal. I avoided the small ring (which wasn't hard on a tri course).

Checked the chain and to my surprise it probably could do with changing, it's at 0.75 on the chain checker which is "should think about changing". I've only done 1100 miles on that chain in good weather (i have another bike for wet rides). Would this small amount of stretch be the cause?

Maybe it's my immense power output Ha.

pilot_pete

Was the chain fitted to a new cassette or a previously used one? If so, as mentioned earlier, check the cassette for wear as if it is excessive it will prematurely wear your new chain (which it sounds like it has done).

PP

robthehungrymonkey

Pilot Pete wrote:

Was the chain fitted to a new cassette or a previously used one? If so, as mentioned earlier, check the cassette for wear as if it is excessive it will prematurely wear your new chain (which it sounds like it has done).

PP

The cassette has done exactly the same milage as the chain...