New cassette compatible?

It's likely you'll need a longer chain and a SRAM WiFli rear derailleur. The WiFli series has a longer cage and and knuckle that puts the jockey pulley farther from the axle, allowing a larger maximum cog.

Standard SRAM rear derailleurs were designed for a maximum cassette cog of 28t. While this specification is conservative, and you might be able to add one or two teeth, depending on the shape of your derailleur hanger and the rear dropouts, four is highly unlikely.

To test for adequate chain length, shift to the small chain ring, break the chain, and stretch it around the largest cassette cog and the outer chainring, but not through the derailleurs. The ends of the chain should overlap by at least two links.

Thanks for the info. Being that I will have to change my derailleur and possible the chain, is there an obvious upgrade I should do? I am mostly a recreational rider and enter a few races a year, so i do not need the top end components, ie SRAM Red. But, if there is a fairly affordable upgrade I would do that.

Aside from lighter weight, Red gets you an "aeroglide lower pulley" with ceramic bearings. Otherwise, the only significant difference is weight and finish. Be sure you specify the 10-speed versions, not the new 11-speed.

Before the WiFli option was extended to Red, Force, and Rival, Alberto Contadore used Apex rear derailleurs for the steepest mountain stages of the Giro d'Italia. He may have had his brother install the pulley with the ceramic bearings, though.

Great info, thanks.

FWIW. While you can certainly pony up for a new rear derailleur if that is your inclination, I suspect that if there is a largest Cog limitation with the Rival rear derailleur which would inhibit using it with a Cassette which has a 32t Cog then you can increase the usable Cog size by simply changing the upper pulley wheel from an 11t to a 10t ... Older 8-speed Shimano & 9-and-10-speed Campagnolo derailleurs had 10t pulley wheels. Of course, in some cases it might be less expensive to buy-and-cannibalize a lightly used, vintage 8-speed Shimano rear derailleur if you can find one in your LBS's spare/(obsolete) parts bin.

Just purchased the SRAM Rival Climbers Kit at Wiggle for $154 with free shipping. Comes with PG-1050 cassette, Rival WiFli dereailleur, and PC 1051 chain. Seems like a pretty good deal, and I am looking forward to heading into the mountains with the new setup.

Thanks for the advice.

Cool deal. Happy trails.