Shimano XT vs SRAM Guide Brakes

SRAM is working hard to shrug off a somewhat shaky reputation by producing some really good brakes. Meanwhile Shimano is worshiped for their brakes and continues to refine their already successful products. As we’ve spent quite a bit of time on the latest Shimano M8000 brakes as well as the new SRAM Guide RSC, we thought it was worth taking a look at how they compare.

Stats & Facts
Both brakes and are similarly priced; they’re typically in the $220 to $250 range for the calliper and lever (add $55-$65 extra per rotor). They are similar in weight too; our front XT lever, calliper and hose was 275g while the Guide RSC was 265g. Factor in an extra 116g for a 160mm six-bolt Shimano Ice Tech rotor, or 114g for the equivalent SRAM Centerline and you’re splitting hairs to say there’s a meaningful difference.

Where Shimano runs a pair of large 22mm diameter ceramic pistons, SRAM employs a compact four-pot calliper with 14mm and 16mm pistons. There’s tool-free reach adjust on both brakes and a bite-point adjuster too. The Guide bite-point works via a dial and noticeably alters the amount of free stroke at the lever. This is handy if you have a particular set up preference; maybe you like a lever that grabs just after you touch it or you may prefer a brake that doesn’t work until the lever is almost at the bar—either is possible with the Guide. A screwdriver is needed for the Shimano levers and adjusting it doesn’t seem to change the amount of free stroke.

Installation & Initial Set up

Split clamps feature on both SRAM and Shimano levers, so they can be mounted without removing the grips or gear levers. SRAM’s hinged clamp design seems more likely to mark the handlebars. You need to use grip paste when installing the SRAM levers; doing so reduces the clamping force required to keep everything in place and minimises the risk of handlebar damage. Neglect this simple step and you may wind up over-tightening the clamp, which is potentially dangerous on lightweight handlebars. By comparison, the Shimano clamp has a smooth inner radius that’s kinder on lightweight bars.

As SRAM uses an ambidextrous lever, you can mount them on either side of the bars without needing to swap the hoses. Shimano levers are left and right hand specific, so altering the lever orientation will force you to disconnect and swap the hoses.

When aligning the calliper, it was easier to get the Shimano brakes running drag-free. The pistons retract further, providing a clear gap on either side of the rotor that makes this part of the set up a breeze. We were always able to eliminate the rotor drag on the Guide brakes too, but the long pads and tighter clearance means some extra patience is required.

Bleeding
A basic bleed on the Shimano brakes will deliver a nice solid lever feel with minimal mucking around—this attribute has earned them many fans. While our XT brakes always felt good at the lever, we experienced some variability in the amount of free-stroke. In our initial review on the M8000 groupset, we mentioned that the brakes would ‘pump up’ on some descents and the first two bleeds didn’t resolve the issue.

Since then we’ve put some additional time and effort into the bleed process, varying the calliper and lever position to dislodge a few mystery air pockets. As a result, they are now more consistent but still not entirly perfect. While it’s easy to get the XT brakes 90% right, that final few percent needed to achieve a perfect bleed is much harder to obtain.

The SRAM bleed process is a bit more involved than the ‘quick Shimano onceover’ that most people will do. You’re also dealing with paint-eating DOT fluid rather than mineral oil. Even so, the SRAM bleed isn’t that scary; just take your time when working through the steps and in most cases the Guide brakes will be right after a single bleed. There was one occasion where we must have missed a bit of air and had some lever inconsistency but another bleed had it sorted. Overall the lever feel was definitely more consistent with the SRAM brakes.

Feel & Performance
Both systems offer excellent power and performance—one finger braking is effortless. You may think the two-piston XT brake would lack bite when compared to its four piston counterpart but that’s not the case. Shimano’s ‘Servo-Wave’ lever mechanism seems compensate, providing more than sufficient leverage and power.

As you only need one finger to stop, they work best when lever-end lines up with your index finger. This position is easily achieved with the compact Shimano brake lever but the SRAM lever clamp needs to sit almost 25mm inboard from the grip to achieve the same position in relation to your index finger. None of this affects the performance but the Shimano system looks tidier as a result.

The Shimano brakes are ultra powerful as soon as the lever meets the contact point, almost to the point of being ‘grabby’. The SRAM lever has a slightly softer initial feel that doesn’t snatch your attention in the same manner. Pull a little harder however and the power comes on strong.

The Guide brakes feed the power on steadily, making it easier to hold that fine edge between rolling and locking. That’s not to say you can’t modulate the power with the XT stoppers. You certainly can but you need to get used to the lever feel and have a lighter touch at the bite point. In the end both work brilliantly and you’ll grow accustomed to whichever system that you choose.

Reliability
Beyond the bleed issues that we hit with the XT brakes, we also encountered one other anomaly. There was a one-month period where the XT brakes didn’t see any use. Upon returning to the Shimano setup, the power had dropped right off and the brakes were noisy. With some use the rear brake came good again but the front did not. A front pad swap sorted it out but the issue was puzzling.

If this were a one-off occurrence, I’d assume that some oil must have been splashed onto the pads or rotors, but I’ve encountered the same thing previously with the older generation XTR brakes and I know of other Shimano users who’ve had their pads mysteriously ‘go off’ in the same situation. Maybe a tiny amount of oil seeps past the ceramic pistons when the bike is left sitting or perhaps the pad compound glazes over when they’re not being used for an extended period.

Aside from the occasional tweak of the calliper position to remove some disc rub, the Guide brakes have presented next to no problems. Beyond cutting the hoses to length and bleeding, the Guides have been absolutely trouble-free. The new Centerline rotors are nice and quiet too. Sure they make some noise in the wet but so do the Shimano brakes.

Summing Up
There’s no doubt that SRAM has well and truly caught up in the braking department. We’ve now spent enough time on the Guide RSC brakes to say with some confidence that they’re one of the best brakes on the market; reliable, consistent, adjustable and very powerful with fantastic modulation. Shimano continues to make brilliant brakes and the new generation BR-M8000 is a very slick product. They’ve got masses of power and the excellent pad retraction makes them easy to adjust for drag-free running. With the new XTR-like slim line lever design, they really look the goods too and will complement any high-end bike build.

Shimano Australia  www.shimano.com.au
Monza Imports  www.sram.com