Ingezonden

BikeRadar was able to give you an exclusive early look at SRAM’s
innovative new XX1 1×11 mountain bike drivetrain back in May. But it wasn’t until this week’s Crankworx in
Whister, Canada, that we were able to give it a proper go on the trail. 

They say
patience is a virtue, though, and our first impression is that the groupset was worth the
wait, and that reasonably fit trail riders should find the range more than adequate. It’s light, it looks good, it’s quiet, it’s secure and, most importantly, it
just flat-out works.

One
chainring but plenty of range

Our Specialized
S-Works Enduro loan bike was equipped with a 34T chainring as we headed out for a
spin around Whistler’s Lost Lake trail network. While there were no
huge climbs or bomber downhills, there were still plenty of shorter – but
reasonably steep and technical – ascents and fast, attention-demanding descents,
including part of the Crankworx Enduro course.

Shifts are quick
and precise, with XX-like chain movement across the cassette even under load. We were never at a loss for gears despite having just one chainring. In fact,
we probably could have gone with the 36T option and been comfortable. Moreover, none of the individual jumps on XX1′s massive 10-42T
cassette are disruptingly big, and they’re admirably even across the
spread.

The new cassette features a massive 10-42T range

XX1′s
total range can’t match SRAM’s current 2×10 offerings. But, then again, that’s
not the goal (more on that later). Chainrings will be available from 28 to 38
teeth in two-tooth increments, and the idea is that the user will choose the
gear range ‘window’ that best suits the task at hand. For example, we can
easily foresee gearing down to a 32T chainring for the big mountain climbs of our US office in Boulder,
Colorado. Meanwhile, folks with a more rolling landscape could probably get along fine
with the 36T or even the 38T variant.

To ease gear swaps,
the XX1-specific bolt circle diameter is designed so that chainrings can
easily fit around the crankarm and spider (meaning you won’t have to pull the
driveside arm). There are integrated threads on the chainrings (meaning fewer parts to lose) and the bolt pattern is asymmetric so it’s
impossible to install the ring incorrectly.

Clever tooth
profiling 

More than a few
editors on site were concerned about the lack of a chain guide on our test
bikes, especially considering the 11-speed cassette’s broader range of chain
angles compared to a standard 10-speed setup. 

Nevertheless, none of us had
any chain retention issues, and it’s hard to derail the chain up front
manually given the tall, slightly hooked and alternatingly indexed
‘X-Sync’ chainring tooth profiles that hold onto the new PC-XX1 chain with
impressive tenacity.

In fact, a
separate test crew from another publication rode their similarly guide-free
XX1-equipped bikes down Whistler’s far more demanding Top of the World trail
and had no issues – to the point where one editor insisted that SRAM
had embedded high-power magnets into the CNC-machined aluminum
chainring (alas, there are none).

That being said, SRAM still admits that a guide might be necessary in more extreme conditions. For example, while sponsored rider Jerome Clementz showed up to join our ride sans guide, he used one to win the Crankworx Enduro a few days earlier.

The synchronized teeth mesh perfectly with the new PC-XX1 chain

SRAM has also
integrated a similar, but less extreme, tooth design into the rear derailleur
pulleys. While chain retention generally isn’t an issue back there, we
noticed how quietly the system runs – even in the 10T and 42T
gears. Because XX1 is optimized for a single ring, the chainline is perfectly positioned in the crank.

Moreover, the
inclusion of SRAM’s Type 2 one-way clutch for the pulley cage virtually
eliminates chain slap. Plus, a new finishing process on the PC-XX1 chain
supposedly improves elongation wear by four times compared with the company’s
current 10-speed chains, despite narrower rollers.

Trigger or
twister options

SRAM will offer
XX1 with both trigger and Grip Shift shifter options. We sampled the former, and
while its mechanics are supposedly more closely related to X0, the look and
feel are more akin to the standard XX unit. Clicks are easily audible, with good
tactile feedback overall, albeit with a little tinniness compared with Shimano’s more substantial feel.

As usual, each
downshift push moves the chain across a maximum of three cogs, while the release
trigger does one at a time in rapid-fire succession.

Obviously, XX1′s
1×11 configuration includes no front shifter. Weight and simplicity benefits
aside, riders who run dropper posts will now be able to run remote levers in
a more ergonomic position, beneath the bar. And when things get hectic there’s
also one less set of controls to juggle.

The XX1 trigger shifter is compatible with MatchMaker X mounts, for a neat look

A note on
compatibility

As previously
mentioned, the new XX1 cassette will only mount to the new ‘XD’ cassette body,
which is currently offered only by SRAM, Mavic and DT Swiss. It’s worth keeping in mind that a number of companies use DT Swiss freehub bodies in their own
wheel designs, though, greatly expanding the collection of compatible
offerings.

The new XD freehub body isn’t all that different from a standard SRAM/Shimano driver

According to SRAM’s drivetrain product manager Chris Hilton, a “very, very long list” of other companies have already
signed on as well. This means consumers shouldn’t have much of an issue finding
retrofittable bodies to mount on existing wheels, especially as the design
doesn’t require changes to the axle interface, unlike Shimano’s new 11-speed
Dura-Ace group.

Interested parties
can check out SRAM’s dedicated site for more information on XD, including
detailed drawings and licensing info.

What’s the
point?

Hilton readily admits that XX1 isn’t for everyone, but for
those who are already using 1x drivetrains – or have considered it – the new
group certainly expands the versatility range and decreases some of the
technical barriers to entry. Performance riders will enjoy a more
straightforward drivetrain, with none of the mechanical headaches commonly
associated with multiple chainrings, more chainring clearance (plus, the teeth
are never exposed to rocks and logs) and less parts to fail.

From a manufacturer’s
perspective, there are also the side benefits of not having to worry about
front derailleur placement (meaning chain stays can be shorter and more widely
spaced, for better handling and tire clearance) or the effects of multiple
chainrings on suspension performance. In addition, the
1×11 concept is just simpler to operate. 

The largest cog is a pressed-on aluminum piece

We’re currently waiting for confirmation on XX1 costs. Granted, the premium pricing
(roughly between XX and X0 in terms of total group cost) will put it out of
reach of the masses, but it’s inevitable that SRAM will expand the idea to lower
price points. 

SRAM doesn’t
expect 1×11 drivetrains to completely supplant 2×10 ones – and neither do we.
Nevertheless, we don’t see any downsides at the moment, aside from the slightly
narrowed total gear range. 

Needless to say, one ride of SRAM XX1 wasn’t enough, and we’re aching for more saddle time.

Production XX1
bits should begin shipping in October.

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