What model of Shimano 10s road rear derailleur with highest spring tension

[Erik_A]

What is the model of Shimano 10s road rear derailleur with highest spring tension, that also fits a 11-32 cassette un-officially (with normal, longer non-Campy derailleur hangers)? I am done with SRAM shifters, and want to run 10 speed Shimano road shifters on my cyclocross bike. One of Shimano's neutral support mechanics at an event earlier this year recommended the Ultegra RD-6700. I have also heard that the 105 RD-5701 has a stronger spring than the previous 5700 version. What about Dura-Ace RD-7900?

[tinshedchris]

I've never noticed much of a difference in spring tension from model to model, but imagine the Shimano tech guy's recommendation would be pretty spot on. You'd probably want to look for a 6700-GS for the 11-32 -- Even though you can squeeze a 32 into an SS cage, you often (depending on specific derailleur hanger geometry) have to ramp the B tension up so much that you may not be able to get it to shift well.