Any of SRAM’s Guide brakes are hard to beat for excellent on-trail performance and an easy servicing life, but the Guide RSCs are just plain awesome if you can afford them.
The major performance gain over the Guide RS brakes are the super-smooth cartridge lever pivots. This gives them an ultra-sensitive feel for boosting already excellent modulation to a level of stiction-free HD clarity that’s definitely noticeable if you’re swapping back and forth between the two different brakes. The RSC levers also get subtle but usefully effective bite point adjustment via a simple toothed adjustment wheel buried in the body. There’s not a massive difference between the two extremes, but Guide brakes rarely differ much in feel between levers, so it’s ample for balancing feel between left and right or tuning in your exact preferred bite point.
SRAM’s range of integrated mounts for brakes, shifters and suspension/dropper remotes makes them very easy to fit and they play nicely with Shimano shifters, too. They’re ambidextrous for easy switching and close to bar pivot position, which also amplifies already decent power in terms of actual on-trail feel and effectiveness. So a 180mm rotor (taking the SRAM Guide RSC's weight up to 438g) is more than fine for most rides and riders. Inside edge hose attachment helps them dodge accidental damage, too.
All Guide S4 callipers are now upgraded with the premium features that first appeared on the £310 Guide Ultimate. These include the super simple but wonderfully effective ‘Bleeding Edge’ bleed circuitry. This moves the syringe attachment point to the far end of the calliper so fresh fluid is forced past (and around) the piston for automatic air purging of the whole system rather than bleeding from the lever side of it as on most brakes. They’re already one of the most tolerant systems in terms of splitting and rejoining without the need for bleeding if you’re installing them in internally routed frames, too.
Stainless steel ‘Heat shield’ inserts and alloy piston interfaces that SRAM claims lower peak temperatures in the body of the calliper by up to 20 degrees make them impressively Alp-proof, too.
The stress-free user friendliness of the S4 block is a feature of all SRAM’s current Guide brakes, most of which are priced a lot more affordably than this. So why pay extra for the Guide RSC (or Guide Ultimate)? The short answer is that all the tiny details gives them an unparalleled ability to maintain impeccably consistent control and grip communication between tyre and lever even in the most mental, 'all hell breaking loose' trail situations. This simply makes them among the best full-feature trail brakes available for those who are lucky enough to be able to afford them.