MRP S4 User manual

Step 7
Check the position of the top roller. Only when the bike is com-
pletely bottomed out should the chain be touching the groove in
the top roller. The top roller is designed to be a guide, not to
tension the chain at any point in the bike’s travel. Improper top
roller position may result in broken or lost rollers, bent boo-
merangs and dropped chains. The best method for determining
the top roller position is to remove the spring or air pressure
from the rear shock and bottoming the bike out completely. Ro-
tate the boomerang so that the chain just touches the top roll-
er when the bike is completely bottomed out. Mark the position
of the boomerang. Please note that MRP chain retention devices
are designed to ISCG and ISCG-05 standards. Our experience is
that some frame manufacturers position the tabs not in accor-
dance to the standard. These frames may require modications
or special installation instructions. If you nd you do not have
enough adjustment, it may be due to the frame manufacturer not
following the standards. Please contact MRP for further in-
structions for t.
Step 8
Remove the drive side crank arm. Make sure that the boomerang
is in the position that you determined correct in Step 7 and se-
cure it. If you have ISCG or ISCG-05, tighten the ISCG screws.
If you are using a bottom bracket mount boomerang, tighten the
bottom bracket cup to the manufacturer’s specications. The
boomerang may want to rotate as you tighten the cup, so double
check the position after everything is tight. Reinstall the com-
plete crankset and bottom bracket according to the manufactur-
er’s instructions.
Step 9
Finishing Touches. Make sure that all bolts and screws are
tight. Saddle the bike and bounce around, check to make sure
there is no interference between the guide and the suspension
action or linkage on full-suspension bikes. Check your chain
length by shifting through all gears. It should be easy to shift
through all gears, but not have a lot of extra chain slack. Keep
in mind that most full suspension frames require additional
chain length to accommodate for rear travel. Check chain
length with the chain on the largest rear cog and bottoming out
the bike.
MRPBIKE.COM
970.241.3518
580 North Westgate Dr.
Grand Junction, CO 81505
THE MRP DUAL ROLLER SYSTEM IS
PROTECTED BY U.S. PATENT 5725450
Thank you for purchasing an MRP chain retention system.
MRP invented the bicycle chain retention system in the mid
90’s and forever changed downhill and freeride mountain
biking. MRP’s patented dual roller system found on the
S4 combines ultra-reliable performance, quiet operation,
and near universal frame compatibility. To ensure the
best out of your MRP chain retention system, we strongly
recommend that you have a trained service technician
at your local bike shop install your MRP. A properly
installed MRP will function awlessly every time!
We’ve designed the S4 to be simple to install.
Before beginning your installation, you’ll typically
need these tools:
4mm, 5mm, and 8mm Allen keys, an appropriate BB tool
(for BB mount applications) and a pedal wrench
INSTALLATION INSTRUCTIONS
The S4 is
available in
three different
mounts, make
sure that you
have the right
MRP kit for your
bike.

use of Loctite, one-step cleaners, or solvent based lubricants
can cause premature failure of the bash guard.
Step 5
Install the boomerang to the frame. Follow the instructions
below for the type of mounting system you are using:
ISCG / ISCG-05
If you have ISCG or
ISCG-05 tabs on your
frame, install the boo-
merang with the supplied
4mm bolts. The boomer-
ang is designed to have
30 degrees of rotational
adjustment to allow for
proper positioning of
the top roller. Initially
position the boomerang so that the top roller is at the 11:30
position if you are looking straight-on at the chainring. Tighten
the ISCG screws enough to hold the boomerang in position, but
loose enough that you can rotate it to the proper position in
the steps below.
BOTTOM BRACKET MOUNT
If your bike does not have ISCG tabs, mount the boomerang
by removing the drive side bottom bracket cup and inserting it
through the MRP boomerang. Make sure that there is no grease
around the outside edge of the bottom bracket shell or the
part of the bottom bracket cup that engages the boomerang.
Grease in these areas can allow the boomerang to slip during
contact. Clean these areas with a degreaser if necessary. In
normal set-up, the bottom bracket cup should sit into the re-
cess in the MRP boomerang. Initially position the boomerang so
that the top roller is at the 11:30 position if you are looking
straight on at the chainring. Tighten the bottom bracket cup
enough to hold the boomerang in position, but loose enough
that you can rotate it to the proper position in the steps be-
low.
Step 6
Install the assembled drive side crank arm and bottom bracket
completely according to the manufacturer’s instructions. Po-
sition the rollers so that they are almost touching the bash
guard. The rollers do not need to contact the bash guard, but
they should not be more than a few millimeters away from it. If
the gap between the rollers and bash guard is too large, the
chain may get sucked between the roller and bash guard. Check
to make sure that the groove in the rollers are centered over
the chain. If they are not, you may need to shim the boomerang
and ISCG or ISCG-05 tab interface using the included washers.
INSTALLATION
Step 1
(if your bike is not already assembled, go to Step 3) Using a
pedal wrench remove your pedals.
Step 2
Remove both crank arms, chain, chainrings and drive side bottom
bracket cup according to the manufacturer’s instructions. This
is the perfect time to carefully inspect all of your drivetrain
components to ensure that they are in good working condition.
If any drivetrain components are damaged or worn out, replace
them to ensure the best performance from the S4.
Step 3
Using a 4mm Allen key, loosen the
upper and lower rollers until you
can slide them, in conjunction with
the plastic wear plates, up to the
furthest position outward from
the BB in the adjustment tracks.
Slightly snug them to keep them in
that position.
• The direct bottom bracket mount boomerang attaches to the
bottom bracket with pressure from the bottom bracket cup.
• Both the ISCG and ISCG-05 boomerangs attach to three tabs
around the bottom bracket shell.
If you are unsure if you have ISCG or ISCG-05 tabs, contact
the frame manufacturer. We recommend that you purchase the
proper MRP system for your frame to ensure the best t and
performance possible. MRP does make an adapter that converts
an ISCG MRP kit to bottom bracket mount. This adapter works
in most situations. In a few situations, the adapter may push the
chain line out and reduce performance, require a longer bottom
bracket spindle, or crank modication.
Step 4
Install the bash guard and chainring to the crank spider.
The bash guard should be mounted to the spider in the large
chainring position, outside of the tabs, with the recessed
outer portion underneath the crank arm. The chainring should
be positioned in the middle chainring position, inside of the
tabs. The nut of the chainring bolts should pass through the
chainring from the backside, through the spider, through the
included thin, silver washers (unless using Shimano Saint M810
or SLXM660 cranks), and into the bash guard. You must use the
included thick, black washers under the head of the chainring
bolt. Torque the chainring bolts to 43 in-lbs. If you over tighten
the chainring bolts the polycarbonate material may crack. The