Thanks KCT. So my theory is that if I use a bar end in friction, I'm probably not going to want a RD with more than 10 cogs. The reason is as you point out: the cogs are closer together and your really have to "feel" the shift through. More room for a mis-shift or rubbing. I train on a TT set up that uses a 9-cassette and a Sora RD. It works very well. And honestly, I'm not taking on any mountains, so why would I need an 11 or 12 speed set up? I recall racing around like a nut back in '84 on my Schwinn 10-speed. I really have no need for a 24 speed!

But I may want a 10 cassette, as I may go to a 1x10 set up.