After my crash during the week, I was anxious to get back on the bike. The road rash was painful (at this writing, still is), but would rub against nothing while in the saddle, so riding wouldn’t be a problem.
But I needed to replace my trusty old Schwinn bike computer. It had been flattened when a car ran over it right after my crash. I swung by Wal-Mart after work Friday and picked up a new one.
So, I sat down with the instruction booklet Friday evening and set the computer. I inputted the wheel circumference (after manually measuring it in my driveway), and all the other stuff you’re supposed to do. Saturday morning, I mounted it on the bike for its first ride.
Immediately, I saw that something was wrong. As I pulled out of my driveway, still with only one foot clipped into a pedal, the computer was reading 15 mph. Farther down the block, once I started cruising, it showed a speed in the high 20s.
Hm. I must have set something wrong. I did my ride along a familiar route, so I would be able to save some of the data. But the readings I was getting on the new computer were around twice as high as I should get if it was accurate.
Sunday morning, after resetting the computer for the umpteenth time, I set out on another ride. I had decided to skip the club ride because of my road rash. Although I could ride easy, I didn’t think I was up for a 40-mile, two-and-a-half hour jaunt in the country. Next week.
Again, the computer registered high numbers. I stopped a few blocks into the ride, and adjusted the sensor mounted on the fork. Then I reset the computer to kilometers per hour, assuming that maybe there was a manufacturing flaw, and the miles and kilometer settings had been reversed at the factory. All that got me was cruising speeds upwards of 60 kph.
This disappointed me. I’ve been somewhat smug about not needing a fancy bike computer when all my friends have one. Current speed, max speed, average speed, and distance are really the only numbers I need. But now, after spending considerably more for this unit than the one it replaced ($23), I wasn’t getting any usable readings.
As I pedaled along, I noticed something odd from the front wheel. That sensor magnet was really spinning fast. Why, it looked like it was going twice as fast…oh, crap.
I stopped at the side of the road again, and this time I took off one of the two magnets on the front wheel. When I disconnected the old unit’s wiring and sensor, I had forgotten to take the magnet off the wheel. Instead, I installed the magnet from the new unit. Now, I had two. Double the magnets, double the fun.
I set off again. The speed was right where it should have been — between 12-15 mph. On the slight downhill through a nice subdivision, it registered 26 mph. I rode over to the Veloway, which has a known distance of 3.1 miles per lap, and did two laps. Yep, 3.1 miles each time.
Next time you get a new bike computer, remember to take off the old wheel magnet before you install the new one.
And you wonder why I still call this blog Bike Noob.