mountain unicycle   ...   random thoughts , unicycle
tue 2005-feb-22 17:21:38 pst   ...   permalink

So last Sunday I went on a 16-mile mountain unicycle ride (or "muni ride" as those in the know call it, and yes we know that makes it sound like we're riding the bus in San Francisco).

I borrowed Seth's muni, since he couldn't come that day. I actually got it from him a week in advance, so that I could get used to it by riding it around campus for the week, in place of my (non-mountain) uni that I normally ride as my primary means of transport around campus.

Seth's muni is a KH24 (2004 model) (I mention that it's the 2004 model to distinguish from the fairly different new 2005 model). The noteworthy differences versus my Miyata (circa 1993, though I don't think it's particularly different from the current ones) are: 24-inch wheel instead of 20-inch; fat knobbly tire instead of thinner, not very knobbly tire (though my tire is a bit knobblier than the one pictured at the above page); and 170mm cranks instead of 110mm. (Also of course the whole thing is built to be able to take more abuse.) The knobbliness of the tire doesn't make a huge difference when riding paved roads, but is nice for the off-roading. The bigger wheel is also nice for off-road, because it means you more easily run over small obstacles (branches, say), plus it means that you travel further for each revolution of the wheel. The longer cranks give you better leverage, which is helpful when going uphill, and again, when running over small obstacles. Basically, you only have one gear; a larger wheel with the same cranks is like a higher gear, while longer cranks with the same size wheel is like a lower gear. (I'm not sure whether the end result is a higher or lower gear in this case of larger wheel and longer cranks -- I forget, is leverage linear? i.e. do you just compare the (radius of wheel / radius of crank) ratios? Hm, that would mean that this is a lower gear...)

Anyway, I've been thinking of getting myself a unicycle better suited to muni than my old Miyata. And I've ridden 24-inch wheels before, but always felt that I preferred the 20-inch. When riding on paved roads, I find that in spite of requiring more RPMs, I can easily keep up with (and generally even out-pace) most unicyclists on 24-inchers. So I figured, what do I need the bigger wheel for? A 20-inch is more maneuverable... The uniycles with knobbly tires and robust construction in the 20-inch size are called "trials" unis, rather than munis, since for muni you want a bigger wheel, whereas for trials (fancy moves like hopping up onto things and so on), you don't need the extra travel or running-things-over ability. So I was considering getting a trials uni to use for muni, even though everyone thinks I'm crazy for preferring the smaller wheel... But then since everyone thinks I'm crazy, I figured that before making such a purchase I should probably borrow a 24-incher for this ride and see how I like it.

So as I said, last week I was riding Seth's KH24 around campus. I found that the extra travel of the bigger wheel didn't really make much difference to me (either good or bad), but that the long cranks were just insane -- your whole leg is flying around these immense circles. Plus, since it rained, I discovered that the up-spray on the backs of my legs was much worse than I'm used to, probably mostly because of the bigger wheel, though perhaps also the knobblier tire. And I found that with such a big uni, I felt more self-conscious about bringing it with me inside places (I sometimes lock it up outside, sometimes bring it in with me, depending on the building). Anyway, so I wasn't real thrilled about it, and was still thinking about a trials uni.

Okay, so then I went on this 16-mile ride. There were eight of us for most of the ride. We started with nine, but one person had to bail not very far into the ride after his seat-post broke (at the weld joint to the plate that attaches the post to the seat). Plus there were three other unicyclists on the trail who we remaining eight ran into but didn't actually travel with (not a coincidence that we ran into them -- they went there that day because we were going, but didn't travel with us because they've only been unicycling for two months; I think they didn't do the full 16 miles, but even so it's pretty incredible that they did the section of it that they did with so little unicycle experience). Anyway, it was a great ride, though I'm pretty out of shape and so am still sore two days later.

I actually wound up walking probably 4 miles of it, mostly during the really long, really steep uphill stretch and the really long, not quite as steep uphill stretch that immediately followed the really long, really steep stretch. I had wanted to keep open the option of turning back early (so, for example, I didn't carpool down there), partly due to uncertainly over whether I could make it the whole way, but mostly just due to not wanting to be the weakest link, holding everyone up. The worst thing about being the one that the group has to wait for (besides the fact that you're making everyone wait for you) is that you always get the least amount of rest, since they've been waiting for a bit before you get there. The last ride I went on (with some of these same people), I wasn't generally the slowest, but nearly. And that was a much shorter ride.

But a little ways in, I decided to stick it out and do the whole ride, partly because it seemed like I probably wasn't the slowest, and also because I did want to challenge myself, push my limits. And I'm glad I did, because after all the grueling uphill, the descent (down a different path) was incredibly fun.

And I must say, I'm a convert. I think the descent would not have been as much fun had I been riding a 20-inch wheel -- the 24-inch is great not because of the extra travel with each revolution, but because of the ease of running things over. And the long cranks are great for both that and the uphill climbing. If in fact the smaller wheel is a lower gear, then the ascent might have been easier, but probably not by much, especially considering the percentage of that time that I was actually on the unicycle!

I also understood for the first time how, though clearly not necessary, a hand-brake could be really nice (though Seth's KH24 does not in fact have one, so this is kind of speculation since I haven't actually tried it). Especially on a long ride like this, it would be great to be able to save some of the energy that gets expended pushing back on the upstrokes while going downhill (especially steeper downhills). The other use for a brake (which I'd heard of before, but which didn't seem important) is to allow yourself to "coast" when going downhill, meaning that although your feet still have to circle on the pedals, you basically don't push either on the upstrokes or the downstrokes -- while going downhill, you can accelerate in this way, and it's possible to get going fast enough that the upstrokes and downstrokes come so fast that you're "out of control" in the sense that you can't slow yourself down, even though you're still in control in the sense of the balance. If your uni has a brake, it becomes possible (if scary) to allow yourself to go that fast, since you can then slow down again with the brake.

Now, my only fall of the day where I didn't land on my feet was while we were on the fire road -- so no trees or anything, and it was a nice, straight, not-too-steep downhill bit, so I let myself coast a bit. I figured that since on a 20-incher I can out-pace a lot of unicyclists on 24-inchers, I was curious how fast I could go with the bigger wheel. (It's worth mentioning at this point that I was of course wearing a helmet, as well as wrist, elbow, and knee pads.) Well, I did indeed get going pretty fast! Probably about as fast in RPMs (and therefore even faster in MPH, due to the larger wheel) as I've ever gone on my 20-inch. I wasn't quite at the "out of control" point, where you really need a brake -- I could still have slowed down even without a brake (I think), except that, due to the rain, my left foot slipped off the pedal. I was still balanced just fine though, so I went another three or four revolutions with just my right foot on the pedal, until finally the unicycle went out from under me, and I crashed and rolled in the dirt. The whole thing was pretty awesome!

Not sure what that would have been like with a brake -- possibly when my foot slipped off the pedal, I might have hit the brake hard enough that the unicycle would basically have stopped suddenly while I kept going, and then I might possibly have landed on my feet, though more likely I would have rolled out of it much as I did anyway. If this were to have happened after I'd had a good deal of braking practice, then it's conceivable (though probably not likely) that I could have slowed it down and stayed balanced and gotten my left foot back on the pedal.

I would say that over the course of the day, most of my dismounts were due to lack of confidence, and I think once I get used to what kinds of things I can and can't run over on that kind of uni, I'll be able to stay mounted more of the time and will therefore have even more fun at it.

So anyway, the end result is that I've now ordered myself a KH24. I decided to get the 2004 model (which is still available, though presumably only while supplies last), largely just because the 2005 model is blue, instead of black. But also because the improvements don't seem significant for my purposes and the old model is cheaper. And I went ahead and ordered it with a brake.

I figure I'll probably go back to riding the 20-inch around campus, since it's really just off-road that it seems to matter to me, and I think I do still like the smaller wheel for day-to-day riding. The one thing on campus for which the bigger wheel might be handy is practicing going down stairs, which really isn't all that hard (even on a 20-inch), it's just scary as hell...

And maybe at some point I'll also get a trials unicycle. Heck, maybe I'll even start practicing my hopping. But that might be expecting a bit much.

wed 2005-feb-23 09:49:11 pst
posted by Zoe

I've been thinking some about crank arm length vs. wheel size lately. I've been using my long crank armed 26 inch MUNI for BANG events, and I do, indeed, notice that my legs are going around in huge circles, which seems like a lot more effort than I need to be putting in. I've considered using my 20 inch uni for BANG, but its frame is ridiculously heavy, it has a significantly shorter distance traveled per wheel turn, and I know I can't get up to the same RPMs that you reach on your 20 inch. I should figure out the gear ratios of my two unicycles, and use the higher geared one, I guess. What I really want is a 24 inch with short crank arms, but I have a very hard time justifying my owning a third unicycle given how rarely I ride the unicycles I already own.

Well, in any case, if you want to go on some less intimidating MUNI rides once you have your new MUNI, you and Seth and I should get together and go for rides occasionally. Maybe if I actually used my MUNI for MUNIing, I could better justify buying a different unicycle for BANGing.

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