Product Test: RK’s GB520MXU Sealed Chain
By: Jason Giacchino
We’ve all heard the old philosophical brainteaser, if a tree falls in the woods and there’s no one around to hear it, does it make a sound? To add to the unanswerable riddles we’ll present our own with a unique ATV twist: Is it still an O-ring chain if it doesn’t have O-rings? RK seems to think so and in the case of the GB520MXU, we have to agree.
It doesn’t take a scholar to realize the simple fact that your chain takes a lot of abuse on even the most docile of rides. The final link between your ATV’s engine output and the rear axel itself, it is the chain that withstands massive loads of force and extreme friction. Add in the fact that it’s often peppered with stones, dirt, mud, and water-spray while managing such extremes and it really comes as no surprise that riders would be interested in as much protection against the elements as possible.
O-ring chains, which were popular in many other arenas for their superior lubrication and thus chain-life made their way into the ATV game in effort to solve some of the scenarios mentioned above. The downside of course was that they were more expensive, heavier (since they contained more parts), and wider (to make room for the O-rings). The bad news is that these factors contribute to a loss in efficiency, after all, powering more mass results in more friction and drag.
RK has taken direct aim at the issue by releasing a chain that attempts to capture the benefits of an O-ring system without the inherent disadvantages. Enter the RK GB520MXU; a name perhaps better suited to NSA code breakers than your average ATV rider. Designed specifically for motocross applications, this particular chain is rated up to 500cc so big bore and open class riders would be better suited to looking into the 750cc rated GB520EXW. RK calls this particular model a sealed-ring chain (rather than O-ring) and here’s how it works.
Using much flatter seals than traditional O-rings, the GB520MXU incorporates a pair of tiny grooves within each seal as a means of trapping and holding vital lubrication. As an added bonus, the flatter seals reduce the point of contact being made with the metal of the links and hence decrease resistance. As a result, the GB doesn’t actually look like a typical “extra-wide” O-ring chain. About the only visible proof that you’re sporting something special comes in the form of the chain’s color, which as if touched by King Midas himself, comes only in gold.
The good news is that a standard chain breaker is all you need to remove links. RK leaves no stone unturned and even includes the flat rubber seals to be applied on the master link itself!
Fanatics need not worry about added weight as we took our GB520MXU on to the scales against a whole plethora of competing chains and get this- the sealed-ring MXU weighed less than our non-sealed stocker! Suffice it to say, this means it’s certainly lighter than most traditional O-ring chains on the market as well.
The real deal sealer here is the GB520’s durability. We’ve been running it hard and in all sorts of muck, mud, and goo since winter faded and the chain still looks and rolls like the day we installed it. Removing the chain and measuring it reveals that it has suffered no stretching in the two and a half months of daily abuse we’ve subjected it to. Keep in mind that a non-stretched chain means less wear on sprockets as well.
The only complaint we can come up with for this product is the price, which at 6 (120 link length) is more than double the asking price of an OEM replacement. However, we offset such considerations by reminding ourselves that it will pay for itself by having to be replaced far less often.
There’s no question that O-ring chains are a great addition to the world of ATVs, especially on today’s high output 450s; they last longer, take abuse better, and don’t require the endless lubrication efforts of a standard chain. The only downside until now has been increased weight, more resistance (drag), and initial cost. RK has addressed two of the three issues with the GB520MXU right off the bat. And if the words of Meatloaf are of any consolation: two out of three ain’t bad.
For more head over to:
http://www.rkexcelamerica.com