They’re not just for cross-county racers anymore
Trail riders have been reluctant to purchase carbon fiber rims for two reasons. First, they are expensive (like the Reynolds MTN AM carbon fiber wheelset that’ll set you back $1800). And second, most carbon-rimmed wheels are intended for cross-country racers (not like the MTN AM wheelset). Reynolds didn’t break a price barrier, but they have broken the “for-racers-only” stigma with this wheelset.
uses a high-modulus carbon fiber rim. The rim is 25 millimeters deep and 21 millimeters wide. Reynolds uses DT Swiss for their hubs and spokes. The 28-spoke wheels use a straight-pull spoke design, alloy cassette bodies and DT Swiss double-butted spokes with traditional, exposed alloy nipples. The hubs accept six-bolt brake rotors only.
Our 26-inch MTN AM wheelset came with standard quick-release skewers for a 9-millimeter axle and included a parts kit containing four sets of press-in hub caps to configure the wheels for use with a 15-millimeter, 20-millimeter, 12x135-millimeter or a 12x142-millimeter thru-axle. Also in the kit is a roll of rim tape and air valves for converting the wheels to tubeless.
The weights broke down to 1 pound, 14.7 ounces for the rear wheel (naked) and 1 pound, 9.9 ounces for the front wheel (naked).
Field test results:
The MTN AM carbon fiber wheels look burly, with their deep profile and extra rim width, but feel light in hand. The stick-on graphics will be the first thing any self-respecting weight weenie will peel off after unpacking the wheels.
We took advantage of the wide rims (that give the tires a better bite) and decided to use Bontrager XR1 Team Issue 26x2-inch tires and run them tubeless.
Reynolds recommends using only plastic tire tools for mountain tires, but we went with one better. Unexpectedly, the tires could be mounted to the rim by hand. We added Stan’s Sealant and inflated. Surprise number two: the tires popped into the rim’s bead easily using a floor pump for inflation. We can’t promise that every tire will mount easily, but our pick sure did.
We ran into problems keeping the tires inflated. It took multiple tries over a 24-hour period before the Stan’s finally sealed the air inside the tire. Our problem was traced to the valve stems that we had to overtighten to get a seal. Once they sealed, we never had a leakage issue, but we came within 20 pumps of resorting to tubes.
When the dust had settled (or better, when the Stan’s sealed the leaks), we had taken just over a half-pound out of each wheel. This fact has little relevance to you, because it all depends on how much your current wheels weigh, not what our old wheels weighed. Still, we were in for a treat. Half a pound off a wheel is a big difference. The first pedal strokes on the MTN AM wheels had us wondering if the bike had been secretly equipped with an electric-assist motor.
It is tough to beat DT Swiss in the hub department, and Reynolds made a good move partnering with them. The rear hub makes a cool ratcheting sound without ever bugging you. The cassette engagement is quick and adds to the wheel’s fast acceleration. The rims are stiff enough for any long-travel trailbike application.
We intentionally put ridiculous side loads on the wheels and sensed bottom bracket and suspension flex, but no wheel flexing. Our gamble of using low- profile tires paid off. We never wished for more bite, even under hard braking.
The hardest aspect of testing carbon fiber wheels correctly is that it takes three to five years to complete the testing. That’s because Reynolds and other carbon fiber rim suppliers argue the high cost can be justified because the wheels will last so much longer than aluminum rims. Friends, there is no way for Mountain Bike Action to prove or challenge that claim today. Reynolds does offer a little piece of mind with an optional Reynolds Assurance Program (RAP) that is a two-year damage protection plan. The plan is not cheap. It sets you back $250, or about an additional 14 percent of the cost of the wheel.
This product, like all expensive carbon fiber rims, requires a little blind faith on the rider’s part that the wheels will indeed last long enough to make the $1800 entry fee justifiable. If you are super tough on wheels (you know who you are), the Reynolds MTN AM wheels, along with the RAP, make sense. And if you have plenty of disposable income, nothing blings out a bike like carbon fiber rims. The rest of us will have to do a little soul-searching before plunking down this type of dough.
This review originally appeared in our July 2012 issue.
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