Hi,

You will need a new rear mech, cassette, chain and shifters. Not sure about the front mech but a 10 speed one might work.

A ten speed chainset will be fine.

You will need to remove a cog from the cassette and place the spare spacer at the back of the cassette to fit it on a 10 speed wheel.

I am running the 685 shifter with 105 and have 3 pairs of wheels. One is 11 speed the other two 10 speed. I have to adjust the low limit screw to stop over shifting into the spokes.

It works fine as a 10 speed though the shift down the cassette where you remove the cog can be a bit hit and miss.

Regards

I upgraded to RS 685 hydraulic brakes that meant an upgrade to 11 speed at the back – new cassette, rear mech and chain. Kept the 105 front mech and chai nset and it all works well. The hydraulic brakes are fantastic and are well worth the upgrade. Loads of stopping power. Another league compared to the BB7’s they replaced.