Crankbrothers Cobalt XC Disc Wheelset
Crankbrothers is based out of the one and only, Laguna Beach, California. With inspiration coming from Apple, Bang & Olufsen, Smart Car, and Lego what could possibly fail? First it was a radical pedal design, and then simple and elegant multi-tools. The brand has established itself not by inventing new products all together, but by reinventing existing ones. They basically go out to re-invent the wheel with everything they do. A few months back a pair of the radically different Crankbrothers Cobalt XC wheels landed on our desk for review. To be honest we had not heard a lot of feedback at the time, so it began as an unbiased review from the beginning.
To begin, the Cobalt packaging looked more like something from an Apple concept store than a mountain bike company. Out of the box the wheels weighed 1560g for the set, minus skewers. By comparison the Mavic CrossMax SL set weighed 1610g and the Industry Nine XC Wheelset weighed 1620g. While installing our cassette we did have one slight surprise when the entire free hub body slid off while in the vise. Upon further inspection and phone call, we discovered that nothing holds the free hub on except for a perfect fitting system, then the skewer and rear triangle of the bike. Of course this will never cause any issue when riding, but it was a surprise nonetheless. It’s not all bad though, with this in mind we now know servicing on the fly is easier than just about anything else out there. Once exposed, we saw the six pawls which drive the heart of the rear wheel, and ultimately the bike. They were coated with a very light oil to keep them engaging easily without attracting excess dirt and debris. Everything was kept together with a thin tension ring, so there was no worry of the tiny pawls finding their way onto our shop floor. Between the free hub body and hub shell was a thin rubber gasket to keep things sealed up. Once we slid the free hub body back onto the axle we were good to go.
We mounted a pair of Schwalbe Rocket Ron UST specific tires to the 6061-T6 aluminum welded rim; it measured 19mm internal width. Crankbrothers recommends running any tire between 1.9-2.3". As always, we dropped a small cup of Stan's Tire Sealant in before sealing up the tires. There was no issue mounting the bead onto the rim, and even more importantly they sealed up immediately when inflated with our air compressor.The removable valve stem is similar to the widely popular Mavic version, but Crankbrothers uses a slight convex shape where it seats itself into the inside of the rim.
The rim is UST certified but will also accommodate any non-UST tire. What makes this design truly unique is that it has no spoke holes in the rim. This allows the rim to be extremely stiff while still keeping a minimal profile. Crank Brother used double butted (2.0/1.6/2.0) spokes from the highly regarded Belgium spoke manufacturer Sapim. To connect the 24 spokes Crankbrothers used 12 small vertical "ribs" around the perimeter of the rim, holding two spokes each side-by-side. Rather than being drilled in 24 places like a traditional rim, each pair of spokes connect with a small steel pin where they meet the rim through a single hole. Because the rim itself is not drilled, it greatly increases stiffness and fatigue life, all the while eliminating the chance of air seeping out of spoke holes.
After running through the pin, each spoke met with a corresponding nipple half way down the wheel. They were threaded together using a standard sized nipple, so no special spoke wrenches are needed. The elongated nipple is threaded around the spokes in a male/female arrangement. Throughout the two-month test our front wheel stayed perfectly true, so there was no need to play with adjustment. A bent spoke on the rear lead us to believe a decent size rock found its way into the wheel. This turned out to be a good thing for the review as we could see how much adjustment this design actually allowed. We were pleasantly surprised at how predictable and simple the truing was. Just as with a traditional style wheel it worked its way back into alignment. However, we still don't know how well the wheel can be trued if it were to have a significant wobble. On a side note — we were surprised that the set did not come with any extra spokes. Granted they are readily available from Crankbrothers direct, but it could take a week turnaround just to get rolling again. Maybe they can take a page from Industry Nine and include a few spare spokes for that extra bit of convenience should something go unplanned.
At the heart of the Cobalt wheels are oversized hubs, accepting 6-bolt rotors only. The front uses a 17mm axle, while the rear beefs it up to 25mm internally. The wheels came setup with quick release style hubs, 100mm spacing in the front and 135mm in the rear. Because these hubs were both oversized to begin with, they could easily be converted to accept 15mm thru axles with a simple $40 adaptor kit. The rear hub uses two 25x37x7 and two 17x28x7 sealed cartridge bearings.
On the topic of quick releases, we do love the matching Crankbrothers front/rear split quick release. The quick release closes in one simple motion, but to open you can flip each side independently to split the pulling force in half. This is achieved by using two different sized cams on the end of the lever. We could always snug the QR down tightly without worry of them becoming too tough to open, especially when closed flush against the frame. In Crankbrothers style, they were anodized in cobalt blue to match the nipples (the rims are a slightly lighter color blue).
Before riding the Crankbrothers Cobalt wheelset, we were most recently aboard Mavic CrossMax SL -- one of the most popular wheelsets around for good reason. Even with big shoes to fill we didn't notice any loss of lateral stiffness. The rear hub engages nearly immediately, and although it doesn’t have the distinct sound a Chris King or Industry Nine, it did have a tone of quality. These wheels are all built here in the United States. Thanks to the hand signed build specs card, we know ours were built with love from Sam and Tim. While adjusting air pressure, we experienced no blockage of air flow throughout the test. The valve stem has a wide enough internal diameter to prevent buildup of sealant inside. This is something we will continue to watch as we release little bursts of air to fine tune tire pressure.
As you will see in picture, the spokes on the front wheel came awfully close to our Formula K24 brake caliper, mounted to a Rock Shox Reba fork. Although we would like to see a little more spacing here, it appears the rub on the caliper is from a previous set of wheels because there are no distress marks on the blue nipples/spokes.
During the review we did several XC races and the wheels performed beautifully. Unrelated to actual wheel, we did rip a sidewall resulting in a flat during one race. During the panic of changing a tire with just three miles to go we had difficulty grabbing enough valve stem on our tube for the CO2 to grip. The rim has just enough depth to it to make the process difficult, especially in those conditions. After a few moments we realized we could thread on the nut used from the stock valve stem, and pull our stem out enough to grip for inflating with a CO2.
The Crankbrothers Cobalt wheelset has once again taken an existing product and made it cooler. We won't say these wheels will totally change your life nor make your race lap 3 minutes faster, but they surely won't slow you down. Chances are you'll look like a million bucks and your wheels will look like they belong on Oobject.com.