CR1 Engineering Boxxer Cartridge Review

CR1 Engineering brings a level of suspension performance that is hard to come by in the mountain bike world. Not only do they offer full custom tuning for rear shocks, but they also have fully sealed fork cartridges to fit both Boxxer's and Marzocchi 888 forks. Inside you can read about how the CR1 Boxxer cartridge performed for us over the last eight months that we've been using it and you'll also find a great riding video as well.

Read on...CR1 Engineering Boxxer Cartridge

Watch the video to see the CR1 Engineering cartridge in action

Cory on the CR1 Boxxer

by spoiledgoods

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CR1 Engineering offers many different services, from thorough rebuilds for shocks and forks, to custom tuning if you know exactly what you are looking for. They also provide their fully custom Factory Race System tuning which replaces all of the stock internals of your shock with their own CNC'd and anodized parts. This includes CR1's custom piston, seal head, needle valve, and valve seat, not to mention a shim stack layout that is tailored to you instead of a generic off the shelf tune. Just like their other services, the Factory Race System can be added to nearly any shock on the market today. Perhaps the most interesting upgrade that they offer though are their CR1 fork cartridges. These are available to fit both the '02-'10 RockShox Boxxer chassis, as well as '04-'07 Marzocchi forks, and they completely replace either fork's damping internals. I've been able to put a lot of time on their Boxxer cartridge and you can read about my feelings on it below.




The CR1 Engineering Boxxer cartridge is a sealed unit that completely separates damping oil from lubrication oil, which can present a number of advantages over an open bath system. While suspension theory can be argued about for countless hours, it is generally agreed upon that consistency over extended rough terrain and long term reliability is increased when the fork's damping oil is kept independent from lubrication duties. Another advantage of the CR1 cartridge being sealed is that it makes it infinitely easier to do a simple service as you can remove your fork's lowers for a proper cleaning without having to do a complete rebuild of the damping unit.




If you were to take the CR1 Engineering cartridge apart, which is possible because it is completely user serviceable, you'd find that it's internal parts are either CNC'd and anodized aluminum to prevent breakdown and oil contamination over time, or stainless steel. What you won't find though are any plastic parts or unproven designs because the CR1 cartridge is based off of proven motocross technology. There are two anodized high flow pistons, one for compression and one for rebound duties, that each use CR1's one piece glide rings and are custom shimmed to the riders needs. This is the same basic system that you'd find inside a top end motocross fork, just scaled down. There is a reason that much more demanding sports still use proven flexible steel shims to control damping, there is nothing better for the job, and while mountain bike suspension has progressed a lot in the last few years towards what works best, I've yet to see anything that comes close to CR1's quality and finishing detail.




CR1 also incorporates a hydraulic bottoming cone into the cartridge's lower seal head that ramps up the force needed to bottom the fork in the very last bits of it's travel. Also common on up-scale motocross suspension, the bottoming cone uses oil pressure to slow down the fork's stroke as it enters the oil filled bottoming cup. No cheesy rubber bumpers that can and will break down over time, just proven technology. The cone itself is held in place with a removable C-clip that lets the user install a larger unit for more progressive resistance, or a smaller unit for more linear ending stroke. External adjustments are as simple as you can get: a rebound dial can be found at the bottom of the fork leg and a compression adjuster at the top. There are 40 clicks of adjustment for both.










While the quality of the CR1 unit simply blows away anything else I've seen in the bicycle world, their ability to fully custom valve the cartridge has to be the biggest advantage. Off the shelf suspension has to be built to handle everything from a skinny 100 lb grom that is just starting out, to 250 lb chargers that ride hard and push themselves on every ride. A stock fork will be valved to somewhere in the middle ground and feature a large enough adjustment range to handle a wide range of spring rates that the different end users may need. Conversely, when you order a CR1 cartridge it is tailor made to your weight, riding style, and terrain that you frequent. This sort of service isn't just for riders who happen to know exactly what they want their suspension to be doing and understand the technology, but also for riders who simply want a better handling bike. If you aren't sure what you need, but know you want something better, talk to the guys at CR1 Engineering and let them guide you through the process to put together something that suits your needs.

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Riding impressions

Our CR1 cartridge was installed into a well used 2008 RockShox Boxxer chassis for testing, although they have versions to fit Boxxers from 2002 to 2010 model years. When going this route it is important to give your lowers and stanchion tubes a thorough looking over to check for any damage, also be sure that you're bushings are in good shape. Our fork started life off as a Boxxer Team and although the lowers had some cosmetic damage, the stanchions were in pristine condition. The first impression that I got from the CR1 equipped Boxxer is that it felt a bit under sprung and under damped. The fork is incredibly sensitive to the slightest input and at first felt very eager to enter it's travel at slow speeds. While having great performing and active suspension is always a plus, I've certainly felt far too many stock forks that suffer from being both under sprung and under damped as to feel great on the showroom floor, but suffer badly when on the trail. The first cautionary push had me a bit worried as to whether or not it would come together on the trail and at speed. I needn't have worried.




At slow speeds or on tame terrain the CR1 cartridge gives the feeling of having very little compression damping. It responds well to small trail chatter and absorbs things that less sensitive forks may deflect off of instead of soaking up. This can go a long way in helping traction, especially when the terrain is loose or covered in marbles. The incredibly responsive nature of the CR1 equipped fork will make even the smoothest sliding stock fork feel like it is over damped and not moving freely. The usual result of having such a characteristic on a off the shelf fork is that it will tend to blow through it's travel just when you don't want it to. Not the case with the CR1 Boxxer. Despite being hyperactive, the fork stood up in it's travel incredibly well, much better than when the fork was in stock form, which was a welcome surprise. This trait was especially welcome when riding fast on demanding terrain and under heavy braking that would usually force a fork deep down into it's stoke. I don't pretend to know how CR1's cartridge can be so active, yet feel as if it has more than adequate low speed compression damping that keeps things composed when the trail is steep or under hard braking. This really highlights the advantages of a fork that is valved specifically for you, as opposed to one who's job it is to do a satisfactory job for a lot of riders who would need different spring rates.




The faster and harder you push the CR1 equipped fork, the better it feels. The front wheel moves up and out of the way incredibly fast when smashing through large rocks and roots - you can certainly feel them, but they upset the bike a lot less than they should. I found myself having more confidence when the terrain got big, and possibly even more speed because of that. High speed hits that result in other forks basically feeling like they are locked out were handled much better by the CR1 cartridge. Full travel was used, but the hydraulic bottoming cone did it's job and it was never a hard or jarring hit. When ordering our CR1 cartridge we told Adrian our weight and what we were looking for, as well as how we thought we rode, and it very much feels like he nailed it. Because of this we spent less time fiddling with dials than any other fork in recent memory, but keep in mind that although both the compression and rebound knobs have 40 clicks, their effective range is quite small. This isn't a drawback, but it may not be what some of you are accustomed to. Instead of being able to slow the fork's rebound or compression down an excessive amount, the range is far more usable and riders are less likely to end up with the completely wrong setup. This lets you make subtle differences to the already dialed baseline settings.

While the performance of the CR1 cartridge was certainly impressive, all was not perfect on the reliability front. After nearly eight months of hard use we experienced a loss of damping that was traced back to a small O-ring that must have been nicked at some point. While the fork was still ridable, there was a loss of damping on both the compression and rebound strokes. Being able to call up and speak directly to the guys at CR1 to sort out the problem was definitely a change from the usual warranty runaround and it was nice to know that the problem could be taken care of quickly and easily. Yes, we had a failure, but the performance and customer service would still have me using a CR1 cartridge on my personal bike.




So where does all that leave us? The CR1 performed incredibly well and I would recommend it to anyone who knows how they want their suspension to behave, as well as those riders who may not know all the lingo to what is exactly happening under them, but still want the best performance possible. The cartridge itself is not inexpensive, retailing at $599.99 USD, but keep in mind that that is still much cheaper than a completely new fork that probably won't offer the same level of performance that the CR1 cartridge can bring you, let alone the custom valving. The other option, one that should appeal to a lot of riders, is CR1's ready to ride fork. For $999.99 USD (2011 models will be go up in price slightly) you get a complete 2010 Boxxer chassis with a CR1 cartridge already installed.


Visit CR1 Engineering to get more info and see all of their suspension services.

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