Brilliant MRP G3 brings
chainguide performance, maintenance to new heights
by Don Palermini
 |
The sleeker, more integrated G3 represents a functional and aesthetic step up from the competition.
|
Mountain Racing Products (MRP) have 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.
 |
| The G3's Swingset makes getting at drivetrain parts easy. Simply remove two fixing bolts--one on the upper guide and one on the skid and you're in. |
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.
G3 flaunts bomb-proof
trail manners
I put the G3 through it’s
paces on my all-mountain sled--a 160mm travel Santa Cruz Nomad Carbon equipped
with a SRAM XO 10-speed (non-clutch) rear derailleur, and a Shimano XT (2X)
crankset hosting a single, 33-tooth Praxis Works chainring.
Across a wide range of trail and urban conditions, dislodging the
chain proved impossible--even when doing stupid things to encourage such. Not
only did the chain stay put during the course of more than two months of
aggressive all-mountain rides, but drivetrain clatter was remarkably minimal.
Sessioning rocky, rough trail sections with the rear suspension
intentionally locked-out did more to rattle my dental work than upset the
drivetrain. Whether big hits or rapid-fire staccato stutter, the G3 handled the
rough stuff like the Honeybadger handles a snake--which is to say, it don't
care. In urban drop-to-flat scenarios, the results were the same--rock solid
retention and chain slap-free performance. The G3 also performed flawlessly in
more realistic trail-ride situations, impervious to disruption no matter the
pedigree--uphills, flowy sections, and small to mid-size jumps and drops
produced no ill effects.
 |
| The G3 handled all manner of roots, rocks, stutter bumps and drops with aplomb. |
Installation trials keep
guide a few millimeters shy of perfection
So given the G3's awesome performance, light weight, smart
features and reasonable price, what's not to like? Well, nothing MRP has any
control over, and nothing that's not commonplace on any chainguide. Following
the G3's instructions precisely, I set the spacing between the frame and the
guide's backplate using the prescribed amount of spacers for the Nomad's 73mm
bottom bracket shell. Unfortunately, once I had everything reassembled, the
chain rubbed significantly against the upper guide when the chain was in the
two highest gears. Figuring it perhaps needed to wear itself in, I left it that
way for a few rides until I realized the rubbing wouldn't subside on its own.
In an attempt to remedy the situation, I added another spacer
behind the backplate to push the unit away from the frame--MRP includes washers
of varying thickness for this purpose. This simply moved the rubbing to my low
gears at the other side of the cluster. After grinding up a couple extended
steeps, I concluded it was worse than my original setup because it introduced
more drag when I could afford it least--while climbing.
Frustrated, I finished my ride and gave a call to MRP's Mr. Sears
who patiently and thoroughly explained the many variables effecting
installation. The facing and/or alignment of ISCG tabs and bottom bracket
shells can vary slightly in depth, influencing the side-to-side alignment of
the crank, and ultimately the chainring in relation to the guide. Things like
spindle length and chainline--which is different between 2x and 3x cranks,
incidentally--come into play as well, and can easily account for the kind of
rubbing issues I was having. The best manufacturers can do is give users a
reasonable starting point and suggest some experimentation. In my case it took
four variations of spacer combinations to get acceptable results--which is now
a small but bearable amount of rub in both the largest and smallest gear.
 |
| While the captured hardware and Swingset feature removed some of the PIA-factor from the G3, you still need some trial-and-error on the initial install. Well worth it in the end though. |
Despite the huge advantage of MRPs Swingset for regular
maintenance, there's no getting around the trail-and-error portion of the
initial setup. During my four attempts, I dropped the spacers several times
resulting in extended cussing and multiple do-overs. Note to MRP or Park Tool
or somebody: Please make a
(magnetic?) tool shaped like a BB wrench with ISCG-patterned washer perches you
can use to hold spacers in place until you get the mounting bolts
threaded--thanks.
The bottom line on the G3
Despite the setup niggles, the G3 is an excellent, well-designed,
functional and lightweight chain retention and bashguard solution for
aggressive riding. While my testing did not include true downhill use, its
flawless performance in aggressive all-mountain environments suggests the
discipline's heightened rigor would be well within its capability. With the
likes of the Trek World Racing and Giant downhill teams, as well as all-time
gravity legends Cedric Gracia and Brian Lopes putting time and input into the
G3, you can ride assured it performs at a world class-level. Of all the stories
I've heard from the World Cup circuit, Danny Hart scrambling away from
Sasquatch after throwing a chain is not one of them.
Plusses
- Flawless performance
- Quality construction
- Smart, considered design
- Swingset makes service a breeze
- Lightweight
- Excellent phone and on-line customer support
- Sasquatch-resistant
- Reasonable price
- Carbon option
Minuses
- Potentially finicky initial setup
- Minor chain rub
Pricing Configuration
- G3 with aluminum backplate in ISCG-05, ISCG or BB mount in Mini
(32-36 tooth) or Mega (36-40 tooth) configurations, $150
- G3 with carbon backplate in ISCG-05 or ISCG in Mini (32-36
tooth) or Mega (36-40 tooth) configurations, $200
More info at
970-241-3518
Review originally posted here: MTBr MRP G3 review
