A Savior for the Wet: Donnelly Cycling’s CDG

A Savior for the Wet: Donnelly Cycling’s CDG

Traction is a funny thing. When it comes to bike tires, the basic thinking is that a bigger contact patch will result in more traction. That’s not the whole story though. Traction is a measure of how well something (in our case a tire) grips a given surface. As that contact patch grows the pressure per square centimeter decreases, provided the amount of weight on that contact patch remains consistent. There comes a point where the traction is notably decreased and slides occur more easily.

It’s a phenomenon I was reminded of when I began switching back and forth between 27-plus wheels and tires and 29er wheels and tires. I was finding that a 29×2.3 was giving me better traction than a 27.5×2.8. The surface has a role in this, as well as knob size and shape, but after riding several different flavors of both, for the trails I ride, it was apparent that the larger diameter tires had superior traction in turns.

My experience on the road is similar. On rougher roads the bigger contact patch has always resulted in better traction, in part due to running lower pressure. On smoother surfaces—I’m looking at you Orange County—I don’t notice a difference in traction as much as I notice a difference in control. That is, when a tire breaks free, how able am I to steer into the turn and keep the bike upright. This isn’t a skill I can recommend developing because it requires a pretty high degree of risk; ending up on your hip can have … ramifications. So my experience here has threaded a nether region of not quite deliberate, but not alarmingly accidental, either. My experience is that a wider tire breaks away more gradually, giving me both an early warning system of sorts, as well as more time to react and keep the bike under control.

During my recent tour in Taiwan I experienced several days of rain. The first day of the tour, at the northern coast of the island, which was mopping up the leftovers of a recent typhoon, included truly ark-building amounts of rain. I know I’ve been rained on with that ferocity in the past, but not in more than 20 years. Combined with the fact that part of Taiwan hadn’t gotten much rain recently and the experience can best be described as a Florida-style deluge on the streets of Los Angeles. The roads were slicker than a politician’s promises.

My tires for the trip were the Donnelly Cycling CDG, named for the airport code for Charles de Gaulle in Paris. Donnelly, you may recall is what Clement was until recently. Owner Donn Kellogg elected not to renew his licensing agreement with Clement due to its high cost. So these are the same exact tires, just with a new hot patch on the sidewall. The tire is Donnelly’s nod to the demands of Paris-Roubaix. And while this is a clincher, a style of tire no self-respecting classics rider would dare run at the Hell of the North, the tread is more sophisticated than anything being run over the cobbles.

The CDG comes in two versions: one with a folding bead and one that is tubeless ready. The folding bead goes for $50 while the tubeless goes for $68. The tubeless version has a claimed weight of 420 grams (mine came in at 422g) while the folding bead is a bit lighter, with a claimed weight of 344g. The tire comes in but one width: 30mm. I ran the tires with tubes (because travel bike) and at 70 psi front and 72 psi rear.

The tire contains a puncture protection belt, one that has yet to provide any real benefit in that I have yet to find a single nick or cut in the rubber.

At first glance, the tire looks straightforward enough thanks to a tread with a center strip bordered by mirroring herringbone patterns. But take a closer look and you’ll see that the center strip is covered with tiny nubs only a couple of millimeters long and wide. The herringbone on the sides is deeper and more precisely molded than anything I’ve seen on a bike tire before. The nubs are arranged in an interrupted chevron patter. I couldn’t stop running my thumb over the tread to feel the delicate edges of the herringbone and the nubs on the center tread. Novelty will do that.

So, back to the tour: While I’d done nearly 200 miles on these tires in dry and occasionally dusty/hardpack conditions, it was in the wet that these tires really excelled. They’d already been garden-variety terrific on my early rides, but once I started rolling through standing water and feeling the rear wheel slip in turns—and on one occasion I got a two-wheel drift—what I found notable was how the wheel would ease into the slide and then gradually stop sliding as I turned into it.

I’ve got more than 500 miles on the tires now and while the front tire barely shows any wear at all, I must admit that the little nubs on the center section of the tread of the rear tire have worn away. Were I about to do an event on roads that I knew would be wet, or where dust or sand coated an otherwise hard-packed dirt road, I’d invest in a fresh set to get maximum benefit out of the design.

Final thought: The tire I’d trust for riding on a freshly mopped shopping mall floor.


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    1. Author

      Yes, they do. On a more relative note, they are bigger than any 28 I run and smaller than the 32s I have, no matter which rim.

    2. Robert

      hmm- my conti gp4000 28’s run 31.5 on any wide rim like ardennes or bontrager paradigm elite. But they are 28mm high if that is possible (confused:)

  1. Mike E.

    These sound like they would be awesome for our spring parking garage races, which has some pretty slick concrete involved.

    1. Author

      Indeed. Or if you’re riding your road bike in a skate park. Not sure that’s a thing yet, but in case someone starts….

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