The Zipp Super-9 clincher disc, Zipp's latest and greatest rear wheel, has just landed at BikeRadar towers. We're looking forward to testing it.
Launched at Eurobike a few months ago and aimed at time triallists and triathletes, it claims to be more than just a clincher version of the Super-9 tubular. Zipp say that because of its width and the way the rim interfaces with the tyre, it's actually faster aerodynamically than its tub cousin. It's an interesting premise, and if other aero wheel manufacturers follow suit then the tubular's days are numbered.
Clinchers offer an obvious advantage over tubulars, in that they're easier to fix if you puncture. You can also change tyres easily, to choose the one most suitable for the road surface and conditions you expect to encounter. In the rolling resistance stakes, the best road clinchers are now just as good as the best road tubulars.
One thing you won't get, however, is a lighter wheel. This Super-9 clincher disc weighed 1,092g (2.41lb) on our scales, which is almost 100g lighter than its claimed weight of 1,175g but still 100g heavier than the claimed weight of the Super-9 tubular (995g).
Also, a clincher plus inner tube is usually a little heavier than a tubular plus glue. That said, in our time trialling experience, weight is far less important than aerodynamics when it comes to going fast.
Extra wide for aero and stiffness benefits
The rim of the Super-9 clincher disc is 27.5mm at the tyre bed, tapering to 26.4mm at the brake track. This is to ensure a smooth transition between the rim and a 700x23c tyre, although you should be able to run a 25mm tyre with no significant aero penalty.
The width might cause problems fitting inside your brakes, but Zipp do supply a set of thinner pads (Tangente Platinum Pro Evo) specifically for this wheel. They say the extra width helps with wheel stiffness, however, which should reduce the dreaded wheel rub when you're out of the saddle, provided your frame is up to the task.
Aerodynamic Boundary Layer Control dimples
The Super-9 disc is flat sided, with Zipp's trademark dimples (Aerodynamic Boundary Layer Control) over its surface. These are designed to reduce drag and have long been a part of Zipp's aero arsenal.
The hub is fully compatible with 11-speed cassettes, and can accommodate 10-speeds as well.
The Super-9 should be available in January 2013 for £1,850 / US$2,375 / €2,200. For more information see the Zipp website.