Sunday, February 16, 2014

Tandem: Tire Selection

For several years we used Continental Grand Prix 700x25 on our road Cannondale Tandem. They worked fine on the smooth, mostly debris-free roads of Lancaster County, but were no match for Western Pennsylvania rail trails and rough roads. The Contis rolled well, took corners solidly, and always provided a firm sense of the road.
After some research I decided to try Schwalbe Marathons. I picked up a set of wire bead 700x28s. It took me forever to mount them – they are unbelievably tight and I hope I never have to change a flat on the road – a reason to reconsider these for next time, surely.
I took the tandem out solo a couple of times to test the brakes, shifting, and ride with the new tires. Inevitably some comedic genius would see the empty stoker seat and yell as I rolled by, “Hey! You lost somebody!”
I’d reply, “Oh no! Where’d she go?!”
The tires did not give me the same confidence as the Continentals. The Marathons sounded squishy, turns were wobbly and uncertain, and rolling resistance seemed higher.
I returned, fiddled with the brakes and checked the tire pressure. 80 PSI, yet the range was 80 to 110.
I pumped them up to 105 and tried again – better. Resistance was down, turns were slightly more stable, and the squishy sound was reduced. Still, turns under load with two up are not as solid – there is a definite hunting that seems to be a result of deeper sipes and zig-zag tread pattern. The Contis and Vredestiens we used to ride were basically slicks, with a solid feel all the way over in the lean. But the Marathons seem to grab unevenly on the edges in a turn, resulting in the slight wiggle that reduces confidence.
The Schwalbe Marathons are probably the ultimate tire for wear and puncture resistance. The thread is thick (and is apparent in weight), and the rubber hard. These are probably a good option for western roads where goathead thorns are a problem.
We took a twenty mile ride over rolling terrain past farm yards, along rough shoulders, over gravel and potholes with no complaint. The 28mm wide tires absorb more road shock and inspire confidence for higher speed runs in the 30s. Still, the tire deforms somewhat under load (such as standing to climb a steep, short hill) and the wiggles in the turns are not confidence boosting.
Despite the confidence these tires inspired I switched back to Continental Grand Prix 700x25mm. The Contis provide the stable, smooth, fast ride I'm used to, while being tough enough to inspire confidence.

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