For all out there that want more gearing with there 10spd tandems this set up works great. I have Ultegra 10spd shifters, FSA Triple cranks with a 26 tooth small ring instead of a 30 tooth along with a Shimmano XT long cage rear derailuer. I removed the 11-28 Ultegra rear cassette and replaced it with one of the newley released Shimmano Dyna SLX 11-34 10spd mountain bike cassettes and it works and shifts great ( I also have run a Sram XX10 11-32 with no problems) I now have realy good hill climbing gearing on our Co-Motion tandem. This set up works as well as the same set up in 9spd that we had on our last Co-Motion tandem.
Just thought I would pass this information on
Best Regards to all,