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Old 2018-01-06, 01:12 AM   #53
Viva la revolucion!
Join Date: Jul 2014
Location: Aliso Viejo, California
Age: 50
Posts: 1,083
I just read this entire thread. For the second time. The first time was when I was choosing my first muni, trying to decide on a 24" or 26" wheel. I ended up going with the 26". Fast forward to 2017, duh 2018 I mean, and now, for some riders, the big question is 26" or 27.5"? I think some of the answers to that question are in this thread.

Anyhow, my most recent unicycle is lightweight 24" (Impact 24" frame with smaller, lighter bearings, Exceed titanium hub, KH rim, Schwalbe Smart Sam 2.1" tire, Impact Naomi seat). I have been doing a lot of riding on it, recently. So, here I am, back on this thread, comparing my 24" x 2.1 vs. the 26" x 2.4 (Ardent).

I am a middle aged rider. I have been riding less than 4 years. I am not particularly strong or brave. Whatever I accomplish, is is through practice and improvements in technique and efficiency.

So, what's a more efficient ride, my 24/150 or my 26/165? There are sooo many ways of looking at that question.

The heavier tire/wheel (26") is more efficient to the extent that more mass has more momentum. So, for example, rolling over obstacles, the unicycle is less likely to slow down, which maintains momentum. Conversely, on a steep uphill, where there may be momentary still-stands, the greater inertia works against the rider. And then, on the other hand, pedaling through the weak 12/6 part of the pedal stroke on a slow, slogging hill, the bit of extra momentum of the heavier wheel (and the increased force = MA ) helps get through the weak part of the stroke.

For a given wheel-diameter and crank-length, a graph could be drawn, comparing the pedal position to the strength of the pedal stroke (at that particular pedal position). Some riders describe an increase in the "dead" zone on longer cranks. So, comparing a 24/150 to a 26/165, saying that they both have a similar crank/wheel ratio may not provide a complete enough model for comparing efficiency. I took a couple rides using 165s on the 24", and the dead zone really bothered me. Using 165mm cranks on the 26", however, feels fine. Go figure. Maybe the dead zone is exaggerated on a smaller, lighter wheel with longer cranks, due to greater inertia across the dead zone.

The lighter tire/wheel (24") may be more efficient because when it twitches left and right, it is actually turning into the path of least resistance. But, more energy can be spent trying to make the twitchy unicycle ride straight. The 24" may be a tiny bit easier to pick lines with, making things more efficient. Maybe harder to pick lines, as well, because of the twitchiness. In other words, if you can control it, the twitchy wheel may be more efficient.

The first muni ride I took on the 24", I expended much more energy than was necessary. After several more rides, however, I really started loving it. I felt as if my response times had to speed up on the 24", compared to the 26", and this made riding more engaging. Then I took a ride on the 26", and it felt boring by comparison. My speed on the 24/150 is compatible with the 26/165, because I'm able to spin faster circles on the 150mm cranks. I might try experimenting again with 150s on my 26", but I'm afraid I'd fail climbing many of the local hills.
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