Gerard Vroomen and Andy Kessler are unveiling their Open mountain bike brand today at Sea Otter. Fortunately, they invited me to give it a spin yesterday and take a few photos.
Called the O-1.0, the name refers to it being model number one for the Open brand. It’s a UD carbon fiber 29er hardtail, and it’s light. It’s also pretty stiff with tight handling, and they put some unique features on the frame to help set it apart.
Their geometry is done by stack and reach rather than top tube length. Vroomen says this tells you that if you’re on one frame and you want to go with a 10mm shorter or longer stem, you’re probably on the right size bike. If you want to change stem length 20mm, you need to go to the next size bike. It’ll be offered in four sizes, Small thru XL, each with 20mm changes in reach from 395mm to 455mm (reach is the horizontal distance from the BB center to the top of the headtube).
Now for the good stuff…
Paint finish is a simple matte clearcoat with clean white logos and their four logo colors painted around the bottom of the tapered headtube. They said it’ll become a little more opaque to hide some of the carbon layers. Personally, I thought it looked great the way it was.
The bike come with mechanical cable stops and ports, shown above. But the frame is designed to accommodate electronic shifting like the K-Edge conversions (until Shimano introduces something) and the Acros hydraulic group. For mechanical shifting (aka: cables), the housing stops right here at the headtube and run directly to a guide at the bottom bracket:
Shown on the right, a cable guide plug holds the cables inside the frame. During install, you run the cables through the guide and out of the bottom bracket shell (front der.) or though the chainstay (rear der.), then pop the guide into the BB shell. Once that’s done, you run the cable into the derailleur clamps and set it up.
At left, a good view of the asymmetric BBright bottom bracket.
BBright because it gives you the most stiffness for the weight by using the extra space not used on the non-drive side to flare out the downtube and add diameter for improved strength and stiffness. Kessler says there are other brand cranks that should have something on offer for mountain bikes soon. SRAM makes a road BBright crankset, just nothing for mountain. Yet.
Seat tube is square at the bottom where the side loading forces are greater (reminiscent of Cervelo’s Squoval shape, no?) then rounds off at the top.
Chainstays are somewhat flattened toward the rear. Nothing like Scott or Cannondale’s flex stays, but noticeable. Shift cable exits into a small piece of housing to the rear derailleur. The derailleur hanger bolts onto the carbon dropout.
The post mount rear brake section is reinforced to provide strong braking, and all of the material and mounts are on the chainstays. This lets the seatstays flex as intended.
“Most seatposts have a minimum insertion, but that tells you nothing about what’s safe for the frame,” said Vroomen. “So we put a small hole on the seat tube and i you can see the post through it, you’re safe.”
Monostay seatstay design is thin and flat. He said they could get good torsional stiffness with very little material in the seatstays, and adding more would have reduced vertical compliance. Speaking of which, Kessler says the built-in frame compliance is more for vibration damping than to act as a mini suspension.
Minimal material was also used in the seat tube. Vroomen said when the seatpost is loaded (aka sitting on it), the seat tube bows forward slightly, and slightly more under impact. They’re not making any claims as to total axle movement, but on my ride it seemed to take the edge off without any discernible bounce.
All models use the Rotor crankset because it’s the only brand offering something that fits the 84mm BBright standard used on Cervelos. To keep the matte color theme, they had Rotor do custom cranksets with a mild gloss on matte crankset without their otherwise bold graphics.
I heard 890g being tossed arpund, but Vroomen says a large frame with all hardware is just under 900g, without any bolts or the derailleur hanger it’s around 850g. The large bike built up with all ENVE cockpit and rims, the Rotor cranks and full XTR brakes and drivetrain otherwise came in at just 19lbs 5oz.
Vroomen said the low weight is achieved simply by choosing the right materials and the right layup. For example, he used ultra high modulus carbon fibers, which are more brittle, running alongside the flat sections of the downtube and used stronger materials where they’re needed.
Passes the German EFBe tests, which add about 20% to 30% to the EN standards. Vroomen says this is the lightest mountain bike frame to ever pass it.
“The light weight is nice, but it’s just a by product of building the frame right,” said Vroomen. “It was more important to us to get the stiffness and strength right, but it’s nice that we got both.”
Frame is $2,700 alone and $3,400 with the custom Rotor cranks, BB and chainrings. At launch, they’ll also offer an X0 build with 3T stealth components and DT Swiss wheels and Magura MT6 brakes. Fork will be Rockshox, they’re still deciding why model. Pricing will be about $6,500, but not finalized until fork spec is decided. They’ll also offer a limited edition model with Acros A-GE hydraulic shifting and ENVE wheels ad cockpit. Pricing on this is likely to be around $12,000.
Interestingly, Kessler said another limited edition they’re thinking off will be a 1×11 SRAM build. Hmmm…
FIRST RIDE IMPRESSIONS
Kessler and I rode the flowing singletrack around Laguna Seca for a little more than half an hour. The section we rode had plenty of climbs and descents, corners and straights. As lightweight as the bike is, it didn’t feel flimsy or feathery. It climbed well, feeling stiff under power both seated and standing. The headtube angle is a somewhat steep 72º across all four sizes. I didn’t get the bike into any super tight and twisties, but it felt quick in some of the corners without being twitchy or unstable. Vroomen hinted that it’s designed to be a very quick handling bike, I just didn’t get a chance to really test that.
Overall, it rode well and I can see it appealing to racers looking for something a bit different and super light. The build I weighed was light, but there are lighter wheels out there, and XX still edges out XTR in total group weight, which should make weight weenies super happy.
