Wrenched & Ridden bike reviews: MRP’s 1.X Chainguide

Published June 21, 2009 06:18AM

Giant Factory Team rider Adam Craig won the 2008 national championship cross-country race in Mount Snow, Vermont, using a single 35-tooth chainring and half of MRP’s System 3 Carbon downhill chainguide.

That race underscored his and other top cross-country racers’ commitment to leave behind multiple front chainrings for a light and simple single-ring solution.

Craig’s interest in just one chainring brought him to chainguide manufacturer MRP to ask for a specific, cross-country oriented solution. Until then, MRP had a great approach to keep a chain on, but nothing light enough to make the Giant rider happy, hence the modifications.

“I started running a single ring at the Fort William (Scotland) World Cup last year,” said Craig. “For that, I ran a full System 3 with the lower retention pulley, even. You never need it (a 44-tooth chainring) and it gets rid of some moving parts, so less moving parts on a bike — regardless of if it’s a perfect day, a crappy muddy day or if your stuff is working well or if your stuff is broken — is better, in my opinion.”

MRP officially released its new cross-country specific guide called the 1.X after this year’s Sea Otter Classic in April. It’s a product that was spurred by Craig’s interest and developed and tested with the help of Trek-Oakley-SRAM-Crankbrothers rider and all-mountain world champ, Ross Schnell, who also happens to live in Grand Junction, Colorado, where MRP is based.

Wrenched …

The 1.X is available in two models that accommodate for different chainring combinations. The lighter model weighs 58 grams and accepts chainring range of 32- to 36-teeth, while a slightly heavier model – by four grams – fits a wider range of 32- to 40-teeth. Either model is available in both black and white. We first spotted a prototype of this guide on Craig’s new Anthem X Advanced, which we profiled from Giant’s preseason team camp this spring team camp this spring .

A single chainring is much lighter than a standard three-ring system, but the greatest benefit to a single ring is that it’s infinitely more dependable than any shifting system on the market. It’s all but impervious to mud and, with the right guide, much better at keeping the chain on the ring.

MRP’s 1.X guide clamps to a bike in place of the 2.5mm bottom bracket spacer found on almost all current, external bearing cranksets, including Shimano’s HollowTech, Truvativ’s GXP and FSA’s MegaExo. The 2.5mm-thick alloy back plate is vertically slotted to allow adjustability of the resin guide cage. Chain line is adjustable from 49mm to 50mm via a plastic washer. The guide kit also comes with five 3mm alloy spacers that offer more chainline adjustability and adapt existing chainring bolts and nuts for use with a single chainring.

We paired our 32-40-tooth 1.X guide with one of MRP’s 36-tooth 7075 alloy CNC machined Podium chainrings. The Podium model rings are 3mm thick, without ramps or pins, but with longer teeth. These rings are meant specifically for single-speed and single ring applications. They are available in a range of 32-40-teeth in two-tooth increments.

After converting my Truvativ Noir carbon crank from a triple to a single, adding the 1.X guide and removing the XTR front derailleur, X.0 shifter, a bunch of cable and housing and shortening the chain by about five whole links, my bike lost around three-quarters of a pound, so much weight you can almost feel it in the garage.

… and ridden

Of course, there are issues that one must consider before ditching the triple or double on your current rig: Is the terrain conducive to a single front chainring? Are you willing to keep a couple of chainring options in the toolbox and change from course to course? And more importantly, are your legs strong enough?

My legs answered the latter question, yes, but barely. At first I thought the 36-tooth chainring I chose was too small because I would spin out on road spins when riding to our local trailheads, but after a three-hour haul, with close to 3,000 feet of climbing, I reconsidered with shattered legs. After more use I decided that I was in the right ballpark. The experience led me to believe that on the right course and on good form a single ring makes sense. It’s undoubtedly simpler and lighter, plus a shorter chain and better chain line noticeably improves rear shifting.

The biggest disadvantage, I found, comes up if your legs give out before the finish line. In this case you’re left with no bailout to spin home with, and you may be forced off your bike when a granny might have kept you on.

If you’re having a good day, however, a single ring might be even faster than a triple. It’ll force you to ride a bigger gear on the climbs, which is presumably faster, and it will force you to spin more on the flats and rest more on the downhills and maybe this will allow you to punch it when you get to the hills again.

Craig settled on a 38-tooth ring for just about everything he does, but I’m going to continue plugging along with a 36 on my cross-country race bike. With respect to simpler, better front chainring performance, I’m also looking forward to getting my hands on SRAM’s XX double crankset; its added range may better suit my lack of World Cup fitness. Nonetheless, I can see good use for the 1.X on a dedicated short track race bike with a larger 38- or 40-tooth chainring or on a Super D trail bike with a slightly smaller 34- or 32-tooth ring. In every case, however, the simple and dependable chain retention of the 1.X can pay dividends in highly stressful race situations, as long as your legs can handle it.

Wrenched & Ridden bike reviews: MRP’s 1.X Chainguide

Wrenched …

… and ridden

MRP 1.X chainguide

MRP Podium chainring

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