SRAM v Shimano
I presently have Shimano Ultegra 6600 groupset with a 12-27 rear cassette which I really like. Shimano have stopped making this casssette.
Will the SRAM cassette 12 - 27 be compatible with my present set up? Is this SRAMs 'equivalent' to ultegra range.
(I don't much want to change to the new Shimano 6700 range 11- 28 casette - too wide - and there is some doubt re compatibility anyway I believe)
You should have no issues!
I run RED and FORCE gears on our bikes and have wheels with both 5600 (105) and 1070 cassettes and have not issues.
Interestingly, I borrowed a wheel at a race a while ago with a 6700 cassette and it ran fine.
As far as "what is the equivalent' - FORCE and RiVAL are very close in quality to Ultegra - if you are a weight kind of person, they are very close (the new APEX is probably closer to 105), with RED.
I use 1070 with RED as I can't see the justification for the price and the performance that it offers for an amateur!