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Existentialism-- Just a bloody good excuse to go riding...

Friday, July 9, 2010

Tire Time 3...

Just occurred to me over morning coffee if too big a tire volume with too low a pressure has reached a point of diminishing return even if pinch flat is not a concern anymore.

The fleeting glimpse of the new rear Ardent folding in a turn mentioned in the last tire discussion stayed in my mind after Sun ride.

Having been fixated with big volume especially if it contributes to high tire height off the rims, its like added suspension that can really help ease the kick over 4-6 inch obstacles while fast pedaling through by tweaking to low pressures. But the same low pressure causes the folding and retarded steering on hard banking first observed with the 2.4 RQ upfront. Now I know its the same on the rear.

The issue I suspect lies with the height itself. With so much more above the rim even the toughest side walls would be hard pressed to hold itself under low pressure. Not necessarily that only weak side wall tires will have this problem but short of a really tough wire bead, the deformation under force will be significant. Likewise, it seems that upfront the RQ was pushing dirt rather than rolling over.

This would also explain why the Fat Albert 2.35 cheapo wire bead remains my favorite front tire (rear duty dislike is more to do with the knob designs which imo do not hold the lines the way I would like as it tends to break a little more than I would prefer it to) The FA in comparison is only slightly shorter in height but the cheapo version being a wire bead has hardly deflected as much as the RQ up front under similar low pressure of 18-20 psi.

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