Originally Posted by
chas58
I don't see the benefit of hard and narrow on a tandem either. A 300lb team on 25mm tires would need 140psi to get the deformation as a 28mm tire at 120 psi. Heavier than that, and your off the chart.
Are you 25mm guys pumping your tires up to 140 psi, or you don't mind the higher rolling resistance of a 25mm tire at the same PSI as a 28mm tire (120psi). Just curious as to the thinking and actual inflation used there.
I assume you have seen this chart:
Yeah, there seems to be a movement towards wider tires and lower pressures, with the realization that thinner, high pressure tires do not have the advantage in rolling resistance that has seemed intuitive. Thus, in half-bike, 25 mm tires are gaining favor in comparison to 23 mm, and in tandems, 28 mm.
However, low-resistance
racing tires are hardly available in 25 mm, let alone 28 mm. As mentioned above, the sportiest 28 mm tire is the
Continental 4 Seasons, which will weigh 40 grams more per tire than a 25 mm GP4000s, lack the Black Chili, and have higher rolling resistance.
If 28 mm Conti 4-Seasons are advantageous on tandems, then you'd probably find examples on tandem racing venues, such as RAAM, time trials, etc. The photo's I've seen always seem to have 25 mm, despite what is extrapolated from Bicycling Magazine, June 1989.