Of course my comments were in answer to the question of “Why are bicycles more popular than unicycles”. To reinforce the why, I’ll add that by far the main reason is that people can ride them. If you’ve watched peoples’ reactions to unicycling, a very large percentage of them instantly remark that they could never do it. Only after that come the questions of speed and practicality…
I concur, with the exception of Schlumpf hub (or other gearing). 150mm seems to be the sweet spot for me with my 36" Schlumpf. But on an ungeared 36, I would consider 125s a little long for any ride that doesn’t have a lot of climbing.
All of that makes a lot of sense! I still ride a 36" for my “fitness” rides, but we have a good bike path. Having a common, normal bike bell works great for riders in front of you; the sensible ones just move over without having to look.
But for a more everyday commute, that isn’t really long (I used to do an 16-mile round trip commute by uni), 29" sounds like an optimum size if you have to ride near people and/or in an urban environment. I used to race my 29" with 102mm cranks.
If you have a loose shoelace on a uni, you’ve already made a mistake. Stop and fix it so it can’t come loose, and then remember to do this before every ride! Your collarbones will thank you.
Of course to all of that. But really for most of us, if we commute by unicycle, it’s because we really want to commute by unicycle! When I originally started cycle-commuting to my old job with the 16-mile (25.75 km) round trip, I used by bike (yes, I have one, but it hasn’t been fully assembled in years). But this was mostly to prepare me for making the trip on my relatively new Coker, to make sure I was up to it. It became an easy ride pretty quickly, and I even did it on some very hot days; I think my record was riding home in a temperature of 108 degrees F (42.2 C)! Sweatty.
Actually, given the discussion on why people use a unicycle for commuting (just because), a different answer occurred to me. Depending on what you want to do and your skills levels, you can do trialsy stuff on a 24, for which you’d want at least 125, though 140 is probably more optimum. Not a huge amount slower than shorter cranks, not even much slower than a 29er, but the potential to have lots more fun. The main reason I sometimes think I need to fill the hole in my fleet - a 20er really does feel a bit slow if I want to get anywhere, but even the 26 is a bit too big and unweildy for hopping around stuff, so a 24 might be nice for short distance transport combined with messing around.