Muni experiment - the Camelback Effect?
I took advantage of a local mountain bike race today to test wheel sizes off-road. This is a 2hr race, 3.3mi laps, I usually end up doing 4 laps with a lap time around 35min. The course is ‘semi-technical’. It has lots of small and medium hills (~900ft total climbing), a crapload of curves, a fair amount of roots, and a dozen or so obstacles to get over (logs, wood planks, etc…). Here’s a map an elevation profile.
Making muni comparisons is complicated by the variability in riders skill and in course difficulty. However, I would suggest that some indication of rough number of UPD’s a rider typically makes on a course with a 24" unicycle is a good index to help compare. In this case, for me, I probably fall ~10 times per lap on a 24. I’ve ridden the course a lot, and have made every obstacle except one at least one time, but never strung together one perfect lap. So my wheel-size results here are probably roughly comparable to some course you ride with a 24" and get ~10upd’s.
I rode a kh36 (165mm cranks), then a kh29 (150mm), then a kh24 (150mm), then my last lap back on the kh29. Overall the KH29 had the best lap times and average speed, although the three wheels were actually surprisingly close in their average speeds for the lap (5.3-5.7mph), which works out to 2-3min difference per lap. [note I started my gps a bit late on lap 1]
The 29er was best because it was still agile enough to get over most of the technical bits and also fast enough to take advantage of the zoomy sections. The 24 was roughly equal on the technical sections (but not completely, see below) but felt very slow on zoomy sections. The 36er went fast some times, but was very difficult on the sections of trail that went up and down and up and down the hills, resulting in 21 total upd’s.
In my first lap I really pushed myself hard, I was riding with some mtb’ers, passing and getting passed, and was jazzed to be going fast on my 36er so I didn’t hold back - somehow exceeded my ‘maximum heart rate’ according to Garmin, and spending most of the lap up around 95% heart rate. Maybe not the best strategy for lap1. My legs were shot at the end of this lap and I still had 3 more to go. The 29er let me stay more in the 90-95% range, while the 24 was a bit lower. Exertion wise, I’d put the 36er as too much, the 24 as too little, and the 29er as just right - for this course.
The Camelpack Effect? I was a little surprised I didn’t have fewer upd’s on my 24", but figured it was because I was tired as it was my 3rd lap. So I jumped on my 29er for the last lap to see how many more upd’s I would have than I did on my 2nd lap. To my surprise, I had 1/2 as many. I was really nailing the course, it was fun, and ended up being my fastest lap.
No way my last lap should be the fastest, with fewest upd’s! The only other difference was that I didn’t wear my camelpack on this last lap. I drained it in a break between laps 3-4 so took it off. Does a camelpack really increase your UPD’s by a factor of 2? I figured it would have some minor effect, but not this much. Anyone else noticed this?
-Ro