Cyclometer calibration

I rode the Strada to work the other day, as noted in my pages on mycyclinglog.com. When I got home, I looked at my average speed and distance, and was puzzled that I was showing over 25 miles instead of my 22 miles I usually got on the Vanguard.

The next day, I watched for--and found--mile markers on Westport Road. I found that over the course of four miles, I was off by half a mile--eleven percent.

The cyclometer on the Vanguard is a Vetta RT55, purchased when BikeE was still around. It's served me with minor problems--mostly that the bracket kit was not well-designed and has to have the contacts tweaked from time to time to keep the thing working. I've gotten to work some days to find that the thing didn't read a mile of my journey and was in sleep mode. I haven't bothered to replace the thing for one reason or another--mostly bordering-on-apathy. Still, having it work right is a good thing. Anyway, it doesn't keep its calibration when I change the battery. I had calibrated it well years ago, but at the time of the last battery change I couldn't find the paper on which I had written the calibration number. I got lazy, and used the number I thought was right, based on memory of calibrating another model of computer a LOT of times over the years I worked at Scheller's.

It was off by eleven percent.

Rats.

I was off that bike for a few days--the last day I rode it was Tuesday the 21st. I tried re-calibrating the computer that day before I left the store, but used the online instructions rather than actually measuring the roll-out, and was off by even MORE than eleven percent.I had some time Thursday, and measured the roll-out to calibrate the thing properly, but didn't test it against mile markers until this evening on my way home from the store.

It was within a few yards of dead on. I MIGHT tweak the calibration a bit, but I may leave it alone.

Now to decide whether to edit all my mileages for that bike since early this year based on more accurate calibration. It will add another couple hundred miles to my overall total, of course.


On a different topic--at least slightly--one of the things I enjoy about riding instead of driving is the amount of cool stuff I find along the roadside. I have, among other things, two or three pair of Vice-Grip pliers (the real deal, not imitations!), a four-D-Cell MagLite flashlight, and a couple of screwdrivers that were roadside finds. I've found several dollars in change over the last six months that I would have missed had I not been on a bicycle. This morning, I found a pair of bandage scissors in the middle of Goose Creek Road at Westport Road. They had not been damaged by tires going over them, as they were in one of the inevitable gravel patches found in such an intersection.

Finding stuff--yet another reason to ride instead of driving!