What information about measuring with small wheels?

MEASURING WITH A SMALL BIKE

Two articles appeared in past issues of Measurement News. In the October 1986 issue Wayne Nicoll reported on his use of a Peugeot folding bicycle with 20 inch wheels and a Sturmey-Archer three-speed shift mechanism. He did some riding and noted no particular problems, aside from having to modify the seat post to accommodate his longer-than-average legs. He found that shipping the bike by air was a hassle.

In the January 1987 issue I reported on my experience with a DaHon folding bike. They are still sold at: Dahon Bikes. It had 16 inch wheels, and a three-speed shifter. I installed an Eliminator tube (like a hula-hoop plastic inner tube) in the front wheel, as I had previously had satisfactory experience with it. The ride got harder but I felt safer against flats. I seemed to get satisfactory results on a few local, flat courses.

I took the bike to Pittsburgh to do a validation. I rode with the original measurer. Because the course was hilly and my gearing inadequate I was huffing and puffing on the uphills, and when I really pedaled hard sometimes the front wheel would lift off the ground. Our measurements did not agree well at all. Since I had observed his riding, I accepted the other measurer’s ride as official.

I also took the bike by air to Phoenix, and had no problems with baggage or the subsequent riding, as the course was flat.

At that point I decided that the folding bike was not a very good tool for measuring courses, and I sold the bike. It was a fun little bike though.

Part of the problem may have been the small wheels. Another problem is that the wheel centers are closer together than those on a regular bike. This leads to greater changes in calibration as the rider’s posture changes, shifting the weight fore and aft, or on uphills and downhills, where similar weight shifting occurs.

Thanks, Pete, for reminding me of the specifics. I just had a general sense that the experiments shared in MN were not overwhelmingly positive. Had not thought about the short wheelbase issue, that is a good point. (In fact, how does wheelbase length and "rake" affect measurement in general???).
I have another theoretical objection to small wheels-- once I got a pair of thick-tread tires, during a time when I was sick of all the potholes, etc. that I had to ride through. But I hated them. I don't feel that I got measurements that were consistent either with other measures of the same lengths of roadway or even self-consistent across different temps etc. So I was thinking this is because there is so much rubber in the tires that the (supposedly negative?) cooefficient of expansion of rubber was interfering with the more predictable effect from the change in air pressure due to heat and cold. Just to finish this wacky theory, is it possible that a smaller diameter wheel also has, relatively speaking, thicker treads?
But maybe somebody is out there measuring happily with a little wheel bike! Who knows.