No More Flats Inserts

Oscar, are you saying that the second group, 35,608 clicks, was done in the sun? If not, what were your clicks for the rides in the sun?

Duane,
Both were done in the sun with the temp rising but much faster on pavement than in the shade. I have done 3 other sets of tests over a much wider range of temperatures on a shorter course where there appeared to be modest expansion. Below is a highly abbreviated summary comparing my regular measuring bike at about 95 psi with the No-More-Flats tire.
4/27 95 PSI would add 16.3' and NMF would add 4.5' from 57F to 77 F
6/7 95 PSI adds 33.67' and NMF adds 9.74' from a pavement temp of 73 in early morning shade to 136 F in full sun.
What is concerning is that the test done on my cal course over a minimal range would make me have to do something about the constant for the day with the NMF insert vs the 95 lb tire that in my experience would definitely expand.

I don't understand - the counts seem quite large for a 27 inch or 700 mm wheel.

Are you using a 20 inch wheel?

Qualifications: Temps of 4/27 are on a dead limb near the course thought to be air temp representative. 6/7 should be 5/7. The third test wasjust a test of "swamp cooler" effect from spraying tires 90 seconds. Again the NMFs showed less variability but neither showed the huge difference I expected so I quit after 8 each 500' rides.

The 35K+ counts are the total over 8,000': 8 rides of 1000' each. Tires on both bikes are 26". The NMF has a hub mount Oerth (which runs backwards) and the 95 lb tire bike has a handlebar mount Oerth.

Oscar

I get about 3600 counts per 1000' (19000 counts/mile) with a 26" wheel. Are these really old counters with a different gear ratio perhaps?

Maybe they are old meters. I just double checked and I was getting about 23,500 counts / mile in 2010 on the old bike with a 26" tire and hub mount meter and about the same now with hub mount Oerth and NMF insert. With the handlebar mount Oerth, I get about 24,800 these days.

So I would probably be OK with the NMF tires calibrating at dawn and recalibrating at noon but I would think twice about it on an overcast, constant temp day.

Oscar

How many counts does your counter get with just one revolution?

Both meters get right at 30 counts per revolution.

The tire I have been measuring with is a Kevlar thorn resistant variety 26" x 1.25" and the one with the NMF is a 26" x 1 3/8". I know those are supposed to be different because the Cyclometer I just got has different factors for different widths like 26 x 1.25 is 1953 and 26 x 1.5 is supposed to be 1985. That's what I was trying to set up the day I did the two groups of 8 rides on the cal course. Oddly what finally worked out to be a NMF mile was 2060.

Paul Oerth sold a counter with 30 counts per revolution briefly, if I recall correctly.

This is the continuing saga of my ventures into airless measuring. Airless tire options are somewhat limited by your bike and wheels. I got a 26 x 2.0 airless tire and did not even ride it around the block before measuring with it. Big mistake, it must have gone "kachong" settling in during the ride because I had to drive 15 miles to add 7 feet to a 2 mile course! It has been stable since then but a buddy (170 lb) rode it doing a HM a few weeks ago and was getting 24,712ish when I (150 lb) was getting 24,701. He was also exhausted as you still have to pedal on a slight downhill. That bike also has a rear airless insert 2.0 that feels a little stiffer than the airless tire.
Saturday night before going to do a 5K 65 miles from here, I tried swapping in the 1 3/8" insert tire and found that the brakes on the bike which was using the 2.0 marshmallow tire with the good gears did not have enough travel to hit the rim so I put it all back like it was and rode the marshmallow.

I got another wheel and ordered a 26 x 1 3/8" airless tire expecting it to be much easier to pedal. Still puzzled by why tires from 2 26" bikes are not interchangeable.
So selection and what works remains a matter of trial and error. Contacting the Airless folks is difficult if even possible. The only tires I can find with "equivalent pressure ratings" are all for 700 C types.
Stay tuned.

Oscar Wagner
Johnson City, TN