OPEN 0-1.0 Frame

Open Cycles thought they could do hardtail 29ers like nobody else. Maybe it comes from the fact that Open was started by a co-founder of Cervélo, Gerard Vroomen, a guy who prefers thinking outside the box. Their 0-1.0 is a super light 29er hardtail that is not only in the stratosphere at 871g for a Large, but also laterally stiff, vertically compliant, and more than tough enough to survive hard crashes. At Cervélo, Vroomen innovated both layup and tubing shapes. With 0-1.0 is no different. At the front end, he has a tapered 1 1/8” to 1 1/2” steerer to keep the fork torsionally stiff. The down and top tubes are shaped to brace the the head tube. You’ll notice that the top tube is as high as the upper lip of the head tube. And the downtube is as far from the top tube as possible, also extending to the lower lip of the head tube. The larger distance between the two helps with bracing the head tube. Also, you’ll find that both tubes are as wide at the head tube when they join and then taper to meet the seat tube and bottom bracket respectively. Here, too, Open is maximizing lateral stiffness. The downtube not only changes shape, flattening as it approaches the BBright bottom bracket, but also has a unique mix of plies, with the highest-modulus bits on the sides of the tubing, to maximize stiffness where issues like impact strength aren’t important while the rest of the tube has a mix of lower modulus plies for greater strength and flexibility. The top tube narrows to the seat tube, eventually reducing down to no wider then the width of the 27.2mm seat tube diameter. As mentioned above, this bike takes advantage of the BBright standard. Pioneered in his days at Cervélo, it presents an easel that’s wider and taller to work with. 79mm wide, with the extra width on the non-drive side allows for not only more room for tires and shorter stays, but also better bracing of the left chainstay. The extra diameter, 42mm on the inside, allows for larger bearings and a 30mm bottom bracket spindle. When you look at the chainstays and seat tube coming out of this central area, you’ll see the advantages it confers. The seat tube starts out square-ish and large and tapers to a round 27.2, and the stays start out tall, but flatten quickly. This allows for Open to design in vertical compliance while still having plenty of lateral rigidity. The system is so rigid, there’s no need for a thru-axle to stiffen up the rear end. And, as on their other bikes, the seat stays are wire thin and flattened in the vertical plane for more comfort. The bike is light, stiff, strong; all of which you’ll notice on the trail, but what stands out is the ride. And that’s due to the geometry. They base their numbers on having a 90mm travel fork unsagged (or a 497mm rigid fork, measured axle-to-crown), but 80-100mm travel forks work, too, but the angles change a bit. With the 90mm, the seat tube is a slack 72.5-degrees, which saves system weight, because most will be able to use a zero-setback seatpost. The front end features a 72-degree head angle, which may seem steep, but the precision it yields, is worth it. Even at high speeds, it’s stable enough not to have to over-think where you’re pointing the bike. Open also worked on shifting. All the cables enter the bike on the left side of the head tube via their MultiStop port. It can take electronic or mechanical, or hydraulic shifting, and mechanical or hydraulic braking. It threads in a direct line, no cable stops necessary, through to the bottom bracket cable guide. The brake hose wraps around the bottom bracket and is quieted by a foam bumper you can easily insert. The bike also works with 1x systems, and the S3/E2 mount is embedded in the frame, so you can easily install a front derailleur or not. The rear derailleur hanger has also been redesigned: it is threaded rather than the frame, so you can’t damage the frame if you damage the hanger. The frame comes with: seat collar, headset, bottom bracket guide, foam bumper, cable sleeves, and a spare derailleur hanger. Tires up to 2.25” should fit, but with no tire or rim width standards; it’s just a guide. The Open Cycles 0-1.0 delivers the most performance from the lightest hardtail 29er around.