There is lots to digest from that title alone. Let's start with the name of our new wide carbon clincher - the Rail. The phrase "corners like it was on rails" is as ubiquitous to high end bike reviews today as "laterally stiff, vertically compliant" was a few years ago. The difference is that it actually means something to racers. Cornering matters. If you do it with confidence and aplomb, it's free speed. If you're unsure or cautious, gaps open that you have to burn matches to close. We're calling our new wheel the Rail because it is designed not just to excel in the wind tunnel, but in the real world as well. Racing is accelerating, holding speed on the flats, climbing, bombing descents and railing corners. When we thought about what attributes we wanted to design into a new racing wheelset, we kept all of this in mind. The Rail is (we think) the first wheel optimized for every part of the race course.
That leads us to the next part of the title of this blog I want to focus on - Wide. What is a wide rim? The most common answer is 23mm. But if you think about the attributes of a wide rim - that it results in less casing deformation and broadens the tire's contact patch on the road, increasing road feel and traction - it becomes clear that the width that matters is not the brake track width, but the inside width. The inside width of the Rail is 18mm. By comparison (and not coincidence) the inside width of the Velocity A23 rims we use in our alloy FSWs is also 18mm. We positively love the road feel of good rubber on a set of our FSWs, and deliberately modeled the Rail to replicate that feel with the same inside width.
But alloy brake tracks are thinner than those on carbon clinchers. In order to achieve an 18mm inside width, we needed to expand the brake track to 25mm wide. So technically the Rail is 25mm wide at the brake track, but when we say "Wide" we're actually referring to the 18mm wide on the inside. That's the wide that matters.
By way of reference, here are the brake track and inside widths of some other popular clincher rims:
RIM: Brake Track / Inside
November Rail: 25.0mm / 18.0mm*
ENVE SES: 26.0mm front, 24.0mm rear / 18.0mm front, 15.5mm rear*
November FSW: 22.7mm / 17.8mm
HED C2: 23.0mm / 17.2mm
Stan's NoTubes Alpha: 20.2mm / 17.1mm
Zipp 404 Firecrest: 23.5mm / 16.25mm*#
Mavic Open Pro: 19.7mm / 14.5mm
November RFSC: 21mm / 14.0mm
Mavic Ksyrium: 20mm / 14.0mm
Kinlin XR-300: 18.5mm / 13.7mm
# Brake track width measured at the tire bead. Zipp FC rims widen to 25.2mm at the bottom of the brake track.
You'll see that the delta between inside and brake track width is higher on carbons, which means that a rim that the brand describes as 23mm or even 25mm wide may actually have a narrower inside - where it matters - than a 20mm wide alloy. The width at the brake track likely does matter in the wind tunnel, which is easier to measure and market than "road feel" (something I expect we'll learn all too well in the near future), but our philosophy is that inside width matters more for wheels designed to race fast instead of test fast.
And the final word from the blog title I want to point at here is Proprietary. We've made no secret of our practice of using open mold rims and framesets. Our belief is that performance is a meaningful differentiator, but simply being different does not always mean improved performance. We really like our original open mold RFSCs for their light weight, stiffness and durability. When we elected to switch to a wide carbon clincher however, we couldn't find anything in an open mold that offered the performance we wanted. We found rims at 23mm - 24mm wide, but the inside width wasn't the 18mm or so that we feel strongly is critical for all-around race performance. We also see the trend of going as wide as possible in the bulge for aerodymamics, but that adds a lot of weight that racers jumping out of 80 corners every Saturday start to pick up on. When we couldn't find what met our needs in the market, we set out to build it ourselves. Starting from scratch was the only way we could offer what we think is the ideal racing wheelset, combining road feel, aerodymanics and low rim weight (our target for the Rail is between 475g and 495g).
Does this mean we're abandoning open molds altogether? Not necessarily. What it means is that we will take whatever path necessary to pursue a product strategy that keeps November at the intersection of performance and value, even as the bar is raised on both.
Also, start training, seriously. It's January for chrissake.
Mario – No, they aren't. Read http://www.novemberbicycles.com/blog/2012/11/19/old-and-proved.html for more infor on that. Cedrick – Between CK and WI, we are at our maximum viable number of hub options for standard builds. Each hub has separate spoke lengths we need to verify and track, a new vendor to deal with, and just a whole lot of variables.
Thanks for the detailed answer Dave! Have you guys looked at Alchemy elf/orc hubs for this wheel? Seem like a great option to build into a really strong, stiff wheel… though the WI T11 is killer too.
Are the new wide tubulars proprietary too?
Hi Mike,Sorry to have missed your comment. As you probably read, we used the same exact tire in each test – it was switched from wheel to wheel. It's generally accepted that the tire/rim interface is a source of a lot of turbulence. There is enough data from many angles to support this without relying purely on Bontrager's data. FWIW, I think that it's possible to emphasize different things that happen in a wind tunnel, but the data is the data. Dave
There is significant turbulence at the tire – wheel interface according to Bontrager. http://bontrager.com/technology/r4_aeroWondering if your tests control for tires. Also like to see if Bontagers claims are true