or you can simply slap 29-inch tires on the rims (more on
that in a moment) for hardpacked riding. This versatility
allows a rider to own one bike that does two different things.
WHAT IS IT MADE FROM?
RSD uses a Reynolds 853 steel, air-hardened/heat-treated
main triangle with custom gussets on the top tube and downtube, and a welded bridge between the rear stays. The rear
triangle is made from double-butted, 4130, heat-treated steel
and incorporates adjustable drop-outs (12x142 Maxle-ready)
that easily convert to a single-speed. They even tack on
ISCG-05 tabs to allow for a chainguide.
WHICH COMPONENTS STAND OUT?
RSD uses their own fork with external compression and
rebound adjustments. The 29+wheels and 3-inch-wide tires
steal the show from the frame’s conventional-sized steel
tubing (pun intended). The rims are from UDG (Ultimate
Design Global), which is a consulting company in Taiwan
that helps companies like RSD source components that were
only available to large bike companies in the past.
HOW DOES IT PERFORM?
We spent our time on the Mutant riding it as a true 29+
bike with Surly Knard tires, and then put in more miles with
Bontrager 29-3 Team Issue tires. We are talking a night-and-day difference between the two setups that made us feel we
were doing more of a shootout than a bike test.
The fit: The short top tube puts the rider in an upright
position that is just right for the tight and twisty terrain
that the Mutant was designed for. The bike has an excellent
standover height (even with the larger wheels), thanks to a
radically sloping top tube.
Moving out: Remember, this is two bikes we are riding
here. With the 3-inch-wide Knard tires, it takes a good effort
to get up to speed, and with 12 to 14 psi in the tires, there
was enough flexing that the tire would rub the fork. On the
same section with the Bontrager tires, the Mutant shot up to
speed like a cross-country racer. The rear triangle is a solid
design without noticeable lateral flex.
Cornering: Again, it is a battle of the rubber. The bike
is remarkably agile, even with the 3-inch-wide tires. The
Mutant with the fat tires really needs loose soil, sand or
snow to show its stuff. On hardpacked and loamy terrain,
the Bontrager tires, even stretched to fit those wide rims, did
a great job of hooking up. We didn’t expect that.
Ride quality: Shod with the Knard tires, this is one of the
most plush hardtails we’ve ridden. Slap on the conventional
tires and things turn harsh. It may have been that riding
different tires back-to-back accentuated the ride quality difference, but we found the rear end to be unforgiving in the
Climbing: You can get sloppy and climb out of the saddle
with the fat tires, but the increased grip can’t hide the fact
that you are rotating an extra pound per wheel over conventional tires. Climbs where we threw in the towel on the fat
tires we cleared easily with the Bontragers.
Descending: Okay, not the Mutant’s strong point. The
big tires are fine until their damped-free rebound starts to
bounce and take control. The smaller tires can’t hide the
TRICKS, UPGRADES OR TIPS?
The RSD fork is not ready for prime time yet. It did not
offer enough tire clearance for a 3-inch tire, and its compres-
sion and rebound action were rudimentary. This probably
isn’t news to RSD. They said to expect a V2 this summer.
They offer rigid forks that would be better for the 29+, and
you could use a more popular 4-inch-travel fork the rest of
We would use a Koobi saddle (they have little bumpers in
them) and a carbon fiber seatpost with a bit of give to soften
the bike’s ride when in 29er mode.
To really unleash the promise of the Mutant, you would
want to get a set of 29er wheels (142-millimeter rear spacing
and 15-millimeter front axle) instead of just swapping tires.
The adjustable rear dropouts allow you to shorten the wheelbase, which would liven up the handling while using the
One final word of caution: IMBA reports that many
groomed snow trails will not welcome mountain bikes with
tires narrower than 3. 5 inches. That rules out 29+bikes.
Fast change: Swapping 29-inch tires for 29+ tires is remarkably easy, with no need for tire tools. The tire reduction
changes the bike’s personality, as do the adjustable rear