By Eric McKeegan
The Trail version of Shimano’s excellent XTR stoppers gets all the attention, but there is a Race version that deserves some attention as well. The power and control of the Trail brakes are well documented, but we’ve never had a chance to put the Race version through its paces, until now.
Visually the Race and Trail brakes look much the same, but there are number of differences. The lever itself is carbon fiber rather than aluminum, and it is slightly narrower. There is no pad contact adjustment, reach adjust requires a 2mm Allen key and there is no ServoWave linkage.
Both the master cylinder and caliper are magnesium, rather than the more common (and heavier) aluminum. Alloy backed resin pads are stock, but the finned metallic pads from the Trail brake can be swapped in for more power and better cooling. The pistons are ceramic, which absorbs very little heat, preventing heat transfer to the mineral oil. The front brake (caliper, hose, fluid and lever) weighs in at 185 grams, putting it up there with some of the lightest brakes on the market.
I also got a set of the Freeza rotors (180mm front/160mm rear) to review. The Freeza rotors extend the aluminum in the middle of the rotor into finned radiators for ever better cooling over the standard IceTech rotors. Freeza rotors are for CenterLock hubs only. The Freeza rotors claim cool like the next rotor size up, so smaller and lighter rotors can be used for XC racing.
There is a lot of technology in these brakes, and it isn’t wasted. I was prepared to be unimpressed with the performance, but that was not the case. There is plenty of power, and great lever feel. In fact, I find myself preferring the way the power comes on with the Race rather than the Trail brakes. At times, I find the power of the Trail brakes to be very abrupt, while the Race brakes have a very linear build up in braking power.
The brakes where as close to silent as any I’ve ever used, and I found the resin pads to be plenty powerful for XC and trail bikes. I did a couple of trail rides on basic stainless rotors when I swapped out wheels, and immediately noticed more noise and heat build up. With the correct rotors in place, the power and lack of fade on long downhills, particularly for such a light XC brake, was almost shocking.
Compared to the Trail brake, the Race brake doesn’t have quite the absolute power, but as a light rider, on light bikes, I didn’t find this to be an issue. The lever shape is perfect for one finger braking, and compared some other carbon levers I’ve used, these levers were plenty stiff.
Unlike some super expensive and lightweight component options out there, these XTR Race brakes have little to no tradeoffs for dropping grams, unless you are taking money into the equation. Obviously, all this performance isn’t cheap at $280 per wheel, but this is XTR after all so penny-pinchers need not apply. I’m highly impressed that a brake designed for professional cross-country racing is capable of handling the rigors of trail riding as well.
This is Part 2 of my first real shakedown rides with the new Shimano XTR Di2 group. Read Part 1 here.
In the span of just a few days since receiving the goods I was able to put almost 150 off-road miles on Shimano’s exciting new XTR Di2 electronic components. Here’s a rundown of how it went in the California and Arizona desert.
Yes indeed, automatic shifting and double chainrings, that’s what XTR Di2 is all about. At first mention it’s also perhaps becoming one of the most polarizing features in mountain bike drivetrain history—until you try it. Many riders initial reaction upon hearing about Synchro Shifting is concern over a loss of control over gear selection resulting in unwanted shifts and/or being in the wrong gear at the wrong time. I can tell you that over all those miles I mentioned earlier that never happened. Not once. The truth is as a rider you still have plenty of control over gear selections and the system actually enhances control and certainly increases the speed of gear selection and shifting
Synchro Shift is controlled by the handlebar mounted display unit that serves as the brain. There are three settings: S1 for race style riding, S2 for “trail” riding and manual, which turns off Synchro Shift (a setting I couldn’t use because I didn’t have a front derailleur shifter plugged in.) Besides controlling shift settings the unit displays current rear gear by number, shows battery life, and serves as the recharge and computer port. It can also display and control suspension mode if you have Fox’s electronic iCD suspension plugged in. The battery is the same as Di2 on the road and is mountable in various positions depending on bike frame. In the case of the Di2 specific Pivot Mach 429 SL, it’s integrated and hidden in the frame, as are all the wires.
Plug and play
As I mentioned in my first report, the dynamics of performance can be easily altered via a downloadable computer program. When the display until is plugged into a computer the entire system shows up on the screen with all your options including yes or no for the front shifter, suspension, gear ratios related to when it auto shifts and shift speed.
My changes, besides reversing which button up and down shifted to match the mechanical version, were essentially beefing up the stock S1 and S2 with S1 being based around racing with more time in the big ring and S2 being based around trail riding with more time in the inner ring (both of which, according to the Shimano tech that came up with the custom mapping, makes it feel like 13 gears in the back rather than 11.) I also increased rear derailleur shift speed when holding down the shift button (hold it down and the chain can dance across the entire cassette quicker than you can blink.) The cool thing is because it’s so easy to program you can search for your own settings or just leave it stock which ultimately works amazing—the tinkerer in me just had to be able to say I changed it a bit I guess.
Because it’s so programmable, you can customize deeper by running both shifters and having both control rear shifting, or make one side all upshift and the other all downshift. If you choose to go with Fox’s iCD suspension rather than using the stock Fox button you could program the front shifter to control the fork and shock lockout. Or, set it to manual, leave both shifters on and just enjoy great shifting that way. The one fly in the soup is that thus far Shimano is resisting to make it Mac compatible. Also, making it mobile Android and iOS compatible would be a great thing.
Battery life is less than the road version mainly due to the rear derailleur having to push inward against the clutch mechanism. Expect to get about 20 hours based on how much you shift and temperatures–Shimano Skunk riders did the entire seven day BC Bike Race on one charge. If the battery did begin to die on the trail you’ll lose front shifting ability first followed by rear with it staying in whatever gear you were in when it finally puckers out.
On the trail
Since using XTR Di2 I can say I’ve never used a front shifter with the system and I never will, Synchro Shift is that good. My initial concerns of suddenly being in the wrong gear or getting frustrated with auto shift simply never materialized. As you shift through the cassette you’ll hear a double beep to signal on the next rear shift that the front will be auto shifting and the rear will be dropping up or down a few gears to compensate.
It worked perfectly every time and after just a few miles I was able to anticipate the shift and adjust cadence like I would if I was doing the shift manually except if you tried shifting both front and rear in the same fashion with a cable system you’re risking a jammed or derailed chain—something that has never happened yet with XTR Di2 no matter how sloppy my shift and pedaling form became. I was also always in the right gear at the right time. In fact, I’ve begun to ride (and think) like it’s a single ring in front, the performance of the double ring auto shift is that spot on, intuitive and seamless.
Other performance notes include a nice tactile feel at the shifter. Rather than just being buttons the triggers move just enough to give you a solid feel of shifting. This also prevents accidental shifts. I would like to see more lever position adjustability. At times they seemed to close together and I’d occasionally over extend my thumb and push the wrong trigger. I’ve moved the shifter perch farther inward on the bar as a fix.
Because the 11-40 cassette is designed around double (36/26 chainrings) and even triple setups rather than a single ring (though that is an option) the steps between gear ratios is noticeably tighter than that of SRAM’s 11-speed cassette and as such I found myself shifting a lot more and staying right in the gearing sweet spot everywhere on the trail
Undeniably Shimano has hit a home run with electronic mountain bike shifting. It’s also essentially the same weight as mechanical XTR—a feat Shimano says it achieved because the electronic wires are so much lighter than cables and housing. Price is, as you’d expect: about $3,300 to $3,500 for the complete group including brakes. But as with the Di2 systems for the road you can expect to see it trickle down to at least XT level in the future for a substantial cost savings.
Kudos to Shimano for setting up ride sessions in the tough, rocky terrain of Palm Springs to showcase durability. There were many times squeezing though rock sections at speed where I expected to snag or bang the rear derailleur but it never happened. I left with a few small scrapes on my cranks as a reminder of how unforgiving the desert can be but ultimately there were zero failures or broken parts. As you may have noticed, I haven’t got much to complain about yet.
Now it’s on to long-term east coast testing. Keep an eye on dirtragmag.com for more!