MRP G3 Brings Chainguide Performance and Ease of Maintenance to New Heights


Aside from a crash, a mechanical failure, or an encounter with Sasquatch, the last thing you want when barreling at mach speed through a rock garden is to have your chain bounce off. Catastrophes aside, the distraction anxiety of chain slap also ranks high on the Unwanted List. Finally, protecting your one and only chainring from inevitable impacts on rocks and logs is mission critical in the middle of nowhere, and mission really-nice-to-have even when you’re close to civilization.

Mountain Racing Products (MRP) has built a solid reputation for solving such issues, initially developing dependable, lightweight chainguides and bashguards for the gravity market, then iterating the designs for the trail ride and all-mountain segments as well as cross country use. They even have a cyclocross-specific 1x guide. The versatile G3 cuts a fairly wide swath across the gravity side of the spectrum with intentions ranging from aggressive all-mountain riding and enduro racing to downhill and freeride.

MRP adds better serviceability to proven formula

The G3 features MRP’s proven three-point retention/protection matrix of an upper guide, a lower guide/chain tensioner and a bashguard or “skid” as the company calls it. New to the equation is the integration of the skid and lower guide into a single part, paving the way for Swingset–a clever pair of pivots designed to improve drivetrain serviceability, chainring swaps, and fine tuning. Throw the thoughtful use of just one hex bolt size (4mm) for all mounting and adjustment hardware, and you begin to see how well MRP thinks things through.

In addition to better serviceability, the sleek, integrated design of the skid and lower guide makes the G3 lighter and stronger than previous designs where these parts were separately bolted to the backplate. Made of durable polycarbonate, the lower guide comes with a sealed-bearing idler pulley installed. Fine-tuning the idler is as simple as loosening the mounting bolt and sliding it fore or aft then re-tightening. A captured nut on the back of the guide make these adjustments thankfully fumble-free and easy. MRP also includes the optional G-Slide block, a slippery urethane slider with no moving parts that can be swapped with the pulley for muddy conditions.

Since parts of both the upper and lower guides overlap the chainring to keep the chain secure, prior designs required full removal to get at the parts underneath. To change a chainring on the G2–this guide’s predecessor–you’d end up with a hand full of small parts, bolts and washers which were fiddly to reinstall. With Swingset, you simply remove one fixing bolt from the lower guide and it pivots away. Remove one more bolt to open the upper guide and you have access to everything. The parts remain installed, vastly simplifying the act of servicing or changing the chain, chainring and cranks.

The nylon upper guide is also keyed to the backplate so it holds itself up during installation, eliminating the multi-finger balancing act of lesser designs. It too employs captured hardware, so the mounting nut is always at the ready. A small amount of adjustability is built-in for fine-tuning the guide’s angle to help further minimize chain rub. A short piece of soft plastic tubing on the guide’s tail quiets up-and-down chain slap against the unit itself. Finally, MRP took care to etch the backplate with a height adjustment guide based on chainring size. All one need do is align the top of the guide with the corresponding tooth number–in my case 33–and tighten the bolt. Simple.

G3 targets wide range of bikes, gearing options

According to MRP Marketing Manager Noah Sears–a pro downhill and enduro racer himself–the G3 is made for single-chainring bikes using 8-, 9-, 10- and 11-speed cassettes with standard-tension rear derailleurs. For newer clutch-style mechs–SRAM’s Type 2 and Shimano’s Shadow Plus–as well as for trail bike use, Sears recommends the company’s AMG guide which eschews the lower guide for a slightly lighter, lower-friction setup.

The G3 is compatible with a wide range of current bikes, most of which are listed along with their mount type on the MRP website’s Tech and Fit section. If you don’t see your bike listed, call the company at (970) 241-3518 for compatibility info.

Aluminum, carbon and multiple mounting options available

The standard G3 features an aluminum backplate and is available in three mounting configurations–ISCG-05, ISCG and bottom bracket mount. It also comes in two chainring ranges–the 170 gram G3 Mini for 32-36 tooth chainrings, and the 190 gram G3 Mega for 36-40 tooth setups. Both are available in black or white and retail for $150.

MRP also offers a $200 version of the G3 with a carbon backplate in either ISCG-05 or ISCG mountings. The carbon not only knocks 50 grams off the standard version, but adds unexpected durability to the package. While carbon has a reputation for brittleness, MRP uses a special blend that flexes and returns after impacts. It’s similar to the carbon used in outer space satellite dishes which are crumpled for deployment but spring back to their original shape when released in orbit.

The carbon backplate is available separately as an upgrade, but at $125, it makes more sense to buy a complete carbon G3 from the get-go if you’re going to go the composite route.

Photo Thumbnails (click to enlarge)

About the author: Don Palermini

Chicago-born Don Palermini became a cycling-based life-form in the sixth grade after completing a family road bike tour of his home state. Three years later he bought his first mountain bike to help mitigate the city's pothole-strewn streets, and began exploring the region's unpaved roads and trails. Those rides sparked a much larger journey which includes all manner of bike racing, commuting, on- and off-road bike advocacy, and a 20-plus-year marketing career in the cycling industry that landed him at his current gig with Santa Cruz bicycles. Now residing in the San Francisco Bay Area, his four favorite words in the English language are "breakfast served all day," together in that order.

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  • Dongoose says:

    I’m presuming by “retainer” you mean the G2′s bolt-on bashguard. It really should be replaced (and is available seperately from MRP) particularly if you’ve impacted it enough to destroy it–your chainring, chain, the rest of the guide and even your BB shell are now at risk. The lower guide/guard on the G3 is indeed an integrated piece and will likely cost a little more to replace than the G2′s. Unless you’re completely devoid of skill, however, you won’t be replacing it very often…and you’re actually much more likely to bend the backplate than break the bashguard.

    • chicoan says:

      I broke off the bolt-on bashguard on my G3 within a month of owning the guide. I’m not sure how it happened because I can’t recall crashing. I’m bummed that I now have to pay $45 or so to purchase another plastic guard. I plan to toss the MRP and put that $40 or so towards a different, more reliable guide.

  • jason says:

    +1 im onto my 3rd in 6 months Ill be looking elsewhere I think, very dissapointing

  • Richard says:

    Here 2 broken skids at middle mounting point, within 10 months (no crash, ect, material fault). Second time I’ve got an upgraded version, which seems much more durable hopefully it will last. Great customer service tho, both skid were replaced under warranty!

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