The Range

CNC'd shape proofs to confirm mold detailsIt's time to officially announce the newest member of our rim family, the Range. The Range is a disc specific, tubeless ready, 45mm deep by 27mm wide by 20mm bead seat width carbon rim with an offset spoke bed. We will be launching the preorder at the end of the month, for delivery in late winter. 

After announcing that we had discontinued the Rail 34, you might have thought we were of the "why bother" mindset with regard to carbon. In certain instances, that's true, but as with the Rail 52, this is an instance where carbon does offer a lot of advantages. First, by removing the braking from the rim, the rim can be made lighter. In a rim brake carbon clincher, there's an amount of carbon that's just along for the ride to deal with brake stress and heating (this is why I always die a little inside when I read people talking about improbably light carbon clinchers from unverified sources - they're headed for trouble, and soon). The 45mm deep Range, built into a 24/24 set, will weigh less than a 34mm deep Rail 34 in 20/24 rim brake trim, despite the 65 gram penalty of the disc hubs, plus the extra spokes. 

Second, while disc brake rims can last a long, long time - they don't have brake pads grinding them down, after all - those of you who've done a lot of cross or other off-piste riding on aluminum rims may have noticed a bit of denting at the bead hook. Every disc rim I've retired, save for one that I wrecked in a pileup, has had "terminal denting" on the death certificate. Aluminum rims can suffer a lot of dents before they go off to ride the great gravel grinder in the sky, but at some point they stop holding air as well and you get concerned that they're just going to fold. The threshold of abuse that carbon can take is much much higher than what aluminum can take. These aren't designed to be downhill-proof, but within their use category they're brutes. 

Astute observers may notice that the rim shape looks offset, which it is. The spoke bed is 2.5mm off center. This is a nice thing that discs make readily possible. Off setting the spoke bed allows you to normalize spoke tensions between the load and the off side spokes. To do this with a rim brake rim, you'd need two molds (one for front, one for rear), and between mold costs and production and inventory costs, it's economically unreasonable. With discs, however, you just orient the offset one way for the front, and then flip it for the rear. Instead of eking out somewhere around 55% tension balance between drive and non-drive side on the rear, you get about a 70% ratio. On the front, you get comfortably over 80%. All clincher tires compress the rim, tubeless tires compress the rim more, and really the only you need high tension on the load side spokes (by "load side" we mean the disc side of the front and the drive side of the rear - that's the lingo we propose and are using for that) is to keep the off side spokes tight enough. Between the offset and a carbon rim's improved ability to resist the compression from the tire, that makes a big big gain. 

Aerodynamically, the Range covers a lot of ground (sorry, had to). The bead seat width is 20mm, which favors slightly wider tires than the Rail 52 (18mm bsw). Rails generally get used with tires marked 23 and 25. We envision Ranges getting used with 23s at times, but for sure they're going to see heavy use in CX, and it's certain that 40s will often be used with them. The 20mm bsw is right for that. Working back from there, we've shaped the Range to hold maximum width all the way up to the tire to optimize the transition to wider tires. We avoided going super wide on the overall width for a couple of reasons. First, dedicated road disc bikes have good wheel clearance, but there are limits, and we want these to fit every bike. Second, going too wide would slow them down when you use narrower tires. Since aerodynamics is presumably more important the narrower the tires you're using, this makes sense. Third, and perhaps biggest, we believe that the 20mm bsw is correct for the range (sorry, had to again) of tires you're likely to use with them. To go wider on the outside with a 20mm inside would just torture the shape, or add a bunch of weight, or both. Plus there's the offset to consider. We'll be benchmarking the Range's aerodynamics in the tunnel, but since there are so few similar rims out there, it's a bit of a strange task.

The standard Range build uses Nimbus Ti CLD hubs, available in 24/24 and 24/28, lacing, with CX Ray spokes. We expect the 24/24 to cover most uses. Tubeless tape will be installed and valves will be inclus. Custom builds using King, Tune, and Powertap hubs will be available. Preorder will open late January, with first deliveries following by about one month.

A huge part of design success is identifying and addressing all of the relevant considerations. Given the range (okay, just get used to it) of use cases for the new rim, we're darn near certain that we've hit close to the bullseye on what this rim needs to be.