On Wednesday, February 20, 2019 at 4:32:10 PM UTC-8, Frank Krygowski wrote:
On 2/20/2019 6:30 PM, jbeattie wrote:

Another thing about these tires is that they have a pretty high recommended inflation pressure for a 32mm. IIRC around 90 PSI, which makes the ride like rocks, but if they are under inflated, they ride like slugs. A 10-15 psi difference really affects the perceived "speed" of the tire.

It might be interesting to try some simple coast-down tests. If you have
any hills with pretty consistent slope but not too steep, you could run
them at (say) 75 psi and coast down noting your time between two
landmarks. Then ride back up, inflate to 90 and repeat the trial. If
done on a day without wind, you'd probably get a realistic estimate of
how rolling resistance varies with those two pressures.

You say you don't use cyclometers. But those with cyclometers mounted
might just use the speeds indicated to tell the difference.


--
- Frank Krygowski

Remember that I was describing the coast down test I had up in Cull Canyon where I would coast down a really rough section of road and then it would flatten out and when I hit a 100 yard long patch of new and very smooth pavement the bike would actually accelerate? Everyone wanted to argue that wasn't possible but I did it again and again. As the summer wore on the asphalt aged and got rougher and though it was still pretty smooth the effect had disappeared.