Introduced this season, MRP’s new bottom-bracket mounted chainring guard is ideal for All-Mountain/Trail/Long-Travel XC bikes with triple chainrings. I had a difficult time tracking one down, but Jarrel managed to find one from one of McBike’s distributors. It wasn’t the gold I was hoping for, but it’ll still do the job. The guard is essentially an aluminum plate that mounts between the bottom bracket shell and the drive side bottom bracket bearing. In the case of external bearing type bottom brackets like current Shimano ones, the plate replaces the spacer on the drive side. On the underside of the plate is a curved section of high-impact plastic that extends past the arc of the outer chainring. It’s very similar to the e-thirteen Light Guide, but without the roller/tensioner and upper guide. If e-thirteen had produced a guide-only product similar to this, I’d be reviewing that now instead, since I prefer their products.
The plate is machined out of a piece of 4.8mm stock. Two legs extend downward to serve as attachment points for the plastic grind plate. A section extends upward to act as a chain-drop preventer. That is very clever. The area around the bottom bracket hole and the chain-drop plate is milled down in thickness from the bottom bracket side to 2.5m, so it conforms to the thickness of the standard external bearing bottom bracket spacer. The inside surface is radially staked to provide some friction against the face of the bottom bracket shell to aid in preventing the guide form rotating under frontal impact. I am skeptical if this is actually going to do anything to prevent movement. The chain-drop plate section is cut out for weight reduction and appearance, and the outside edges are radiused. A 1.0mm bottom bracket spacer is provided in case there is a spacing issue between the mounting plate and the granny ring bolts or the chain itself when on the granny ring. According to the MRP website, the plate is available in black or gold anodized. Jarrel only found a distributor listing for the black. There is also an ISCG triple version, as well as smaller versions for double chainring use.
Two outer-double chainring bolts hold the plastic grind plate to the mounting plate. The plastic grind plate appears to be molded out of a similar plastic formulation that e-thirteen uses. The ears at the attachment points are about 6.5mm thick, and the plastic is formed around the underside of the mounting plate, so impacts to the face of the grind plate are transmitted to the mounting plate via the contact point, rather than through the mounting bolts. The grind plate flares out to a 19mm impact face. The MRP logo is cast as raised letters on the inside (bottom bracket side) surface of the grind plate. Painted black, the letters are visible from the non-drive side of the bike. Although it seems counterintuitive, this was probably done because the plate is obscured by the chainring on the drive side.
The install went fairly easily. The MRP instructions direct the user to clean all grease or lube from the face of the BB shell and the backside of the guard plate and to grease the BB cup and outside face of the guard plate, so the cup can easily tighten down without spinning the plate. They are imperative that the plate-to-BB shell interface be grease-free, indicating that this alone will keep the plate from turning when the guard takes an impact. It becomes immediately apparent that if a reasonable amount of moly anti-seize is applied to the BB cup threads, it will ooze out between the cup and plate, and the plate and shell. There is really no avoiding this. I put the monster breaker bar extension pipe between the nose of the guard and the back of the fork crown to prevent any rotation, then cranked down the cup as tight as humanly possible. I was thinking that I could drill a countersunk hole in the chain drop plate section and put a stud in it that went into the hole in my swingarm pivot to help prevent plate rotation, but the skeletonized machine work on the plate makes this impossible. Friction will be the only thing keeping the plate in place.
I put everything back together and took it out for a spin. I couldn’t really find anything to bash into, but found that if I put the wheels on either side of the corner of the planter box in front of the store, I could bounce and the suspension travel would allow the guard to hit the concrete curb. A bunch of impacts, side slides, and lengthwise slides later, the guard was still in place. The bike was already heavy, so I didn’t really feel the weight penalty. On the following Sunday, Ckucke, Root, and I hit the Demon trail, so I had a chance to hit it on the fallen tree, and again on the root on the side loop. The guard worked fine, allowing the bike to slide across the surface without hanging up. On the fallen tree, I missed the ability to use the chainring as a “middle wheel” to drive the bike over the log while pedaling. The trade-off of not getting the teeth ground off or bent on rock-overs or concrete is well worth it though. The chain drop plate function was wonderful! Because of all the pivots and brackets and whatnot on this frame, I was unable to install a seat tube type chain drop plate, so this feature of the XCG is greatly appreciated.
Recommended
Approximately $50 USD
Note: Ckucke ordered a gold one directly from MRP. After two weeks, it didn’t arrive, so he called them back. They told him to wait another week. When it still didn’t show up e called again, and was told, “so what do you want me to do about it?” Thankfully, the guard appeared in the mail the day after, so his anger was mitigated a little, and he got it installed in time for the weekend ride. His worked fine also. MRP had sent it regular USPS First Class, but with no Delivery Confirmation or other trackable number. It just doesn’t make sense to do that with a $50 product when sending it Priority with tracking would have cost maybe a buck more – and they were billing him for the shipping anyway! In the meantime, Jarrel had ordered mine with the regular QBP order and I got mine several days before Ckucke’s arrived. WTF?!
Paul from MRP here. Glad you guys like our new guard. When people order directly from MRP, they have the option of going with USPS (for less money) or by UPS, which usually costs a little more but does offer good trackability. Chucke selected USPS basic service. USPS told us that it usually takes 11 days for mail to reach Hawaii from Colorado. I arrived on Day 15. If you want faster service and better trackability, please select UPS. Thanks.
What upset me is the severe lack of customer service I received. The MRP website says the USPS service takes 3-5 days. Paul’s response to me was “what do you expect me to do about it?” As a sales rep I would never dare tell one of my customers that. MRP never offered a solution, all they told me to do was keep waiting. I contacted them when they told me to if I didn’t receive the item and their response was to just keep waiting. The product is nice, but the company leaves much to desire.
Buy direct from Billy’s BMX – fantastic service & delivery! After fitting this bit of kit I feel so much more confident when it comes to changing external BBs! The instructions & bits included were easy to follow & it looks great on my 2007 Orange 5. What’s great is it looks subtle but has an ‘escence of bling!’. Took my wheels to Afan Forest, Wales & had no fear of ‘loosing teeth’ as I dropped down the big slabs & steps……makes so much sense…do it!
Thanks for the honest review. I ordered one of these to put on my hardtail. I ride at Phoenix’s South Mountain and there are so many rock ledges to bash your big chain ring on that a bash guard is necessary, but it also has long stretches of smooth single track where it sure is nice to have that big chain ring. I hope this is the solution.
Joshua – I think you’ll really like it. Both of us here who are running them have had good results. They’ve held up to boulder and log bashing without any slipping/moving or bending. The slight weight penalty is definitely worth the utility on a long-distance triple MTB!
Hi G Lowe
Just tried putting one on my 08 Orange 5 but it would not fit without chain rub even with the enclosed spacer. But when I put the original 2.5mm plastic spacer on instead that was too much and over compressed the BB.
What combination did you use?
Regards
Chris Watson