rsumbera800

I recently got a good deal on a 2013 Cannondale Supersix Evo Hi-Mod di2 frameset and an FSA SL-K carbon 10 speed wheelset. The frame was orginally built with 11 speed dura ace but I would like to use the wheelset so I am debating whether I should put ultegra 6770 on the bike or use ultegra 6870 and take one cog off the cassette and adjust the limit screw according. Does anyone have any experience with both groups or run the 6870 group on a 10 speed wheelset? I am not even sure if it is possible to go down to 10 speed with di2 components.

Thanks

rpenmanparker 

Sorry, no offense, but downgrading the shifting would be totally back asswards. It is completely likely that FSA makes a replacement freehub body to convert the wheels to 11-speed. They might even already be 11-speed and have a spacer on them to allow them to be used with a 10-speed cassette. Check with FSA first before doing anything else.

The idea of running only 10 cogs on an 11-speed cassette is a valid way to use an existing 10-speed wheel, but I wouldn't limit my riding experience to 10 speeds if it were me and I had a 6870 group. Worst case, if the rear hub cannot be converted, you can have the rear rebuilt on a new hub for much less than $200. That would be my fall back position.

trailflow1

Removing 1 cog from the 11 speed casette is not advised because the makeshift limit stop could potentially damage the motor and it may also cause the battery to drain. That's what happens on the low limit if it is too tight against the stop. There is a safety feature built in that automatically shifts down to the next cog if it is set too tight so i imagine it would be the same at the other end of the cassette.

On mechanical set ups it can be made to work but not Di2.

Try to find a replacement freehub.

Another option is an Edco Monoblock cassette. It has 11 cogs but will fit on any 10 speed freehub
https://www.edco-wheels.co.uk/product/monoblock-cassettes/

or rebuild the wheel with an 11 speed hub.