Sram introduced its Apex drivetrain group this summer. It’s meant to compete with Shimano 105 in terms of price and performance. The group provides 20 speeds, a triple is not an option from Sram. To provide a wide range, an 11-32 10 speed cassette is available. Sram and Shimano cassettes use the same hub design. I knew the cassette would fit on my Shimano 105 hubs.
I was less certain that the 11-32 cassette would fit the rear derailleur or would shift well. I have an Ultegra 6600 “GS” rear derailleur, this has a longer cage than the usual Ultegra. Chain wrap would not be a problem, the GS can handle a triple crankset. The rated capacity on the rear cog is 28, so fitting a 32 might not be possible. The derailleur upper idler wheel must be able to float below the cog when on the largest cog or the rear hanger and/or the derailleur will be damaged. Much to my surprise, the derailleur has the capacity for 32 when installed on my Lynskey road bike. A shorter hanger could reduce the capacity, so this may not be true for all bikes.
Sifting quality was my next concern. Was the cassette going to provide the smooth shifts I had with a 12-27 shimano cassette? The cog spacing on the Sram Apex is greater than the Shimano, with a 11-12-13-15-17-19-21-24-18-32 cog set. Would the indexed spacing provided by the Shimano shifters provide the right increment for the Sram cassette? The Sram cassette provided the same fast & smooth shifts as the Shimano cassette, another pleasing result.
On the road the spacing of the cogs is noticed. If I’m at 20 mph, I can use a 34 chainwheel in combination with 12 cog, and have an 11 or 13 cog to use as the terrain changes. The spacing on the 50 chainwheel is 15-17-19 at the speed range, and the change in cadence in noticeable on the larger chainring.
But the total range in huge, greater than a 50, 39 & 30t triple crankset with a 12-27 cassette. Climbing steep hills at very low speeds is smoother and easier on the legs with the 34 & 32 gearing option. High speed descents at 35 mph can be cranked using the 50 & 11 combination.
This might be the best set-up for hilly routes.