Size Matters

Tubes and Valves

Mavic supply their Cosmic Pro Carbon wheels with their own Yksion Pro tyres and tubes. One small challenge is that, presumably for aerodynamic reasons, the tube's valve only protrudes a little beyond the deep section rims. I found it essentially impossible to get any of my pumps to grip the valve to allow inflation. I was able to attach a CO2 inflator, because that screwed onto the valve. But I couldn't make any normal, mini or track pump attach properly.

The obvious solution was to change the tube for one with a longer valve. The trouble is that the next size up in valve length protrudes a very long way. They're also pretty expensive. In the end, I went for short stem Continental tubes, which have removable cores, and some Topeak presta valve extenders. These can be used with tubes with fixed or removable cores. I also have one long stem tube, which I carry as a spare.

The valve extenders come with a small tool for removing the cores, and replacing them in the extenders. The cores themselves simply screw in. They have a small O ring to ensure a good seal. I chose the standard extender length that leaves about 3cm of valve protruding above the rim on the Mavics.

Tyres

The 883 with Cosmic Pro Carbon wheels comes with 23mm Yksion Pro tyres installed. Over many years of riding my local, north Hampshire roads, I've concluded that only the toughest tyres will survive the local mix of poor surfaces, pot holes and flinty debris. Currently I use Schwalbe's Durano Plus tyres. As I was going to change them anyway, I decided to experiment with 25mm wide tyres.

I'd suspected that the clearances on the 883 might be quite tight, since the Ribble BikeBuilder doesn't include a 25mm option on the wheels, though it is available when buying the wheels separately. It turns out that there is just enough room for 25mm wide tyres, but they need to be deflated when attaching and removing the wheels, to clear the brakes, even when fully backed off.

The Verdict

So far so good. The Duranos perform well around here, as always. The Cosmic's are affected more by cross winds, due to their deep section, than other wheels I've ridden. but that was expected and it's easy to control. The one thing I hadn't bargained for, when choosing a deep section rim, is that they are noisier than conventional wheels. They're not as noisy as a disc wheel, but even so, it can sometimes sound as though you're being followed by a car, even when you're not.