I have run the 70mm version for years in steel, recently in aluminum, it works as well as a rim brake when dry, in the wet it's much better than any rim brake. I recently built a wheel with the newest 90mm drum, it works as well as a 160mm disc, I am impressed. The cost of the SA drum/dyno is very reasonable compared to an SRAM/Shimano disc/dyno, esp if your fork isn't set up for a disc.