The direct-mount version of MRP's 1x is designed for the latest crop of trail bikes with press-fit bottom bracket shells sans ISCG tabs. As it's pitched – a single-ring guide for cross-country hardtails and full-suspension race bikes – it works quite well. In fact, it even impressed us in use on a 6in-travel test rig, although we did drop our chain every so often.
The bike in question was Giant's 2011 Reign – although Ibis's new Mojo SL-R and Trek's Remedy, among others, fall into this same category of super-light trail bikes that have no provision for a chain guide and aren't compatible with standard bottom-bracket-mounted options – and we found that the 1x held the chain on our 34-tooth un-ramped MRP chainring under all but the most extreme situations.
The 1x is a solution for bikes with press-fit bottom brackets and no chain guide tabs
We only had issues when hitting repeated braking bumps in a bike park and after long, rough bouts of trail where we weren't pedaling (which helps keep the chain on the ring). When the chain does derail, however, this almost always requires getting off the bike and replacing it manually. Sometimes the guide needs to be repositioned by loosening its screw and resetting its adjustment.
While we didn't have a chance to test the 1x with Shimano's new Shadow Plus rear mech, we suspect the clutch-type retention of the derailleur would alleviate most, if not all, of the problems we had due to the top-only retention provided by the guide. Still, the 1x isn't a substitute for a fully captured guide in situations that require one, like downhilling or freeriding.
Construction: Mostly made in the USA
MRP machine the alloy bits of all the 1x guides at their in-house machine shop in Grand Junction, Colorado. The molded polycarbonate pieces are manufactured in Taiwan. "Any MRP guide that's delivered in Taiwan for factory assembly is produced 100 percent in Taiwan," Paul Aieta, MRP's sales and marketing manager, told BikeRadar.
"We import the polycarbonate parts and the high-volume alloy back plates from Taiwan for our aftermarket and domestic OEM requirements. Anything custom – Ibis, Intense, Santa Cruz, Pivot, etcetera – or low-unit-volume is machined here in-house. We also produce the best selling alloy back plates here if we run low on stock."
After a solid three months of use – including participation in the Trestle All-Mountain Enduro at Winter Park Resort – our 1x guide is hardly the worse for wear. During the test period we were impressed with how well this simple little guide worked, but specifically how stiff and bend resistant its long direct-mount arm proved.
The 1x's long direct-mount arm is impressively stiff and durable
It's still perfectly straight despite muscling the chain back on, after derailment, without re-adjustment multiple times; likely a testament to the quality of the alloy used. MRP's 1x guide is also available in threaded BB Mount (US$49.99) SRAM direct S3E mount ($69.99) and clamp-style mount ($99.99) versions.