rruff wrote:
It's a shame they test tubulars at higher pressure than clinchers. My favorite thing about tubulars is I can race them at lower pressure than clinchers with less risk of flat, and in my testing on real world roads I have not found a situation where higher pressure is faster than lower pressure (tested between 60 and 120 psi).
I'm interested in your protocol for that testing, and what your roads are like.
IME clinchers with latex tubes can be run at low pressure also. I've been running 70 psi on the chipseal, 23mm front and 25 rear, 170 lb.
i've done indoor Crr testing on rollers using Tom A's formulas (thank you). indoors, i can run things in a much more controlled fashion.
for the outdoor testing, i had to be a little bit looser. my competitions tend to be on chip-sealed road, so i picked a road with what i felt was representative/decent chip seal. (i race in CA, OR, UT, NV, AZ, NM, WA, CO, WY.....and less often east of the mississippi.)
i picked a steep climb (~10%) in a relatively protected area on a low-wind day. not all wind could be eliminated, but i figured the low speeds of climbing this grade would further minimize any effect of wind.
i'm pretty good at riding in a relatively narrow power band. i did 10' repeats at a pretty reasonable power (think it was 4w/kilo, something that was easy to keep consistent).
i started out at high pressure (something like 115 psi -- don't have my notes in front of me) and then let out air with each run...i think it was 15psi.
i simply noted how far i made it on each run. every time i dropped pressure, i made it farther -- and not just a couple meters. again, i don't have my data in front of me (this was 3 years ago), but the effect was fairly linear. small data set, sure, but the results for each step were pretty close if memory serves.
what i found was that there was no pressure too low where i did not travel further than the prior step -- even pressures that i would NOT race (~60psi).
i got the results i was interested in. for me, the message was to always race as low as i can get away with. this is a balance of road hazards (e.g. potholes--though i race tubulars so pinch flats aren't really a thing), the type of race (in a RR with 100 racers i'm more likely to hit stuff vs, say, an uphill time trial), and handling.
hope that helps.
