bump!

I was wondering about the old "15% tire drop" chart recently and googled it up, only fo find this post I forgot I had written!

The original links are dead, but here's a Rene Herse article with the chart in it.

Nowadays my commuter is wearing 2 inch ThickSlicks, and the past week I was finding they seemed a little too soft. The pump gauge this morning told me they were both down to 20. I increased the rear to 35 and the front to 30, and the ride in to work felt fine, probably I didn't need to go that high (but they'll find their way back down over the coming weeks).

So the formula which would require 150*600/(50*50) + .75*50 - 25 = 48.5 (plus or minus, depending on uneven front/rear load split of my 260lb+heavy bike) is way too high.

It must be that, since the chart stops at 37, the extrapolation of what the chart is showing is not really valid all the way out to W=50. I'm virtually certain that the 30/35 I rode this morning, was not dropping 15%. I don't think 20/20 was even dropping that much.