MRP’S S4 is the latest incarnation of their original System 1 dual-roller chain guide. It has been firmly fixed to one of our test bikes since it took on the rigours of the mighty Megavalanche in Alpe d’Huez.
The S4 is best suited to all-mountain and downhill duties, and it was spot-on for our Scott Genius LT test rig. Fitting was a doddle, and it was easy to adjust and tweak to ensure the best possible chainline. The new thinner backplate increases frame clearance and makes it compatible with more frames, which is sure to be a winner.
We do use the term a lot, but the MRP S4 has truly proved to be bombproof. The full polycarbonate bashguard is thick enough, even with the honeycomb pattern on the rear side, and it’s recessed on the front to reduce weight. The bashguard has taken numerous bottom-outs onto plenty of rocks during testing, and it survived them all.
It is a proper fit-and-forget bit of kit, mainly because of its faultless working and silent running. It’s available to fit ISCG and ISCG-05 tabs, and has a bottom bracket mounting option too. You can choose from black or white and there are two versions, to fit 32-36t or 36-44t chainrings.