I definitely need to do some testing!
I have the 2.3 Fast Trak Controls, 2.25 Aspens and 2.4 Aspens. I anticipate I’ll be on the 2.25 or 2.4 Aspens, depending on the course.
I used to ride Fast Traks in 2014-2015 and liked them, but the tire has changed quite a lot since then. I only rode them twice on my new Epic and while I did like them, I missed the predictability of the Aspens (drifty, but you know what it’s doing and know where it’s limits are) and although I don’t have any data to back it up, the Fast Traks felt slower. Gotta test that to know, though.
They are heavier than I anticipated, though. The Fast Trak Controls measured 680/681g, where as the 2.25 Aspens were 638/640g and the 2.4 Aspens were 698/701g.
Between the 2.25 and 2.4 Aspens, this one is tricky. I feel like the 2.4s roll slower on a perfectly smooth road, but I don’t race on perfectly smooth roads. They are very impressive at increasing your traction (particularly when climbing) and they do a lot to help preserve momentum on bumping, rocky trail.
But, whether it’s in my head or not, I find myself thinking their increased size also comes with a rolling resistance penalty. I just can’t understand why Nino seems to run 2.4s all the time, even at a race like Cape Epic. If he’s doing that, I’d like to think they have data showing he isn’t bleeding watts, otherwise I’d assume he wouldn’t use them.
I am using Tubolight inserts in the Roval Control SLs (can’t wait to swap those rims for ENVE M525s, but that’s another thread for another day), so I have been trying pressures as low as 12.5psi all the way up to 23psi with the 2.4 Aspens. The sweetspot for me in terms of handling and preservation of momentum on rough terrain seems to be ~16psi (150lb rider weight), whereas that sweetspot seems to shift to 18.5psi with the 2.25s.
I am planning on doing some testing this spring for all 3 tires.
Record wheel speed at 150w, 200w, 250w, 300w and 350w with all three tires on the rollers. (This is likely the worse test in terms of applicable data since tires aren’t designed to roll on a smooth drum, but will be interesting just the same.)
Coasting rolldown tests on road, gravel and typical trail where the gradient starts downhill and ends up uphill. I start at the same spot, no pedaling, take the same line and record the distance traveled before I stop.
Record time on 3 climbing segments at 300w. One climb will be a consistent and hard-packed surface fire road climb, the second will be a consistent and soft fire road climb and the third will be a consistent and rocky/bumpy fire road climb.
Hopefully that will give me an idea of when to use which tire.