Bicycle Computer on the gpz

Julian Solomensky jsolo at
Mon May 7 17:24:16 PDT 2007

My saga with the speedo replacement prompted me to get a bicycle computer for more accuracy.

The zx11 unit on the average reads about 5 mph too high.  Even more at higher speeds (70 vs 62 actual).

I saw some pics on Art Lischer's pic page, liked the installation and figured I could do something similar.

The unit I got was the Sigma BC1606L - it has back light capability so it should work at night.  Shows all the typical functions including timers, clock, max/avg speed, trip distance, total odo, and a few others I can't recall (cadence - like that's going to help on a motorcycle).  $25 or $26+tax from REI locally.

I really liked the clever magnet Art used for his (little thing, about the size of a dime), but while waiting to order and/or see if he has any more I tried the one that comes with the unit.  Originally I thought it would be too weak to pulse the receiver given the distance and would require one of those rare earth magnets.

The one included with the unit looks like a slightly larger tylenol capsule shape wise.  I attached it to the brake rotor carrier as can be seen in the pic below.  Three cable ties were used.  Two to secure the only and one at the outer edge.  If it's going to go anywhere it's going to want to go outward, so that third cable stop ought to stop it.

The pickup was attached using an old oil filter oring!  Don't ask!  It was something I had on hand which worked very nicely actually.  The cable tie around it is for extra measure.  I'd say the pickup is about 1/8" to 3/16" away from the magnet on the carrier.

The bracket for the main unit is designed to fit on a bicycle handlebar.  It has a curvature builtin.  The closest thing on the triple tree that resembled a curved surface was the side of the clip on.  I did pick up some heavy duty double sided tape from radio shack (the 3m VHB stuff), but opted to see how well the included sticky works.  Seems to hold pretty good actually, so I may just leave it that way.  When routing the cables, car must be taken to ensure there is enough slack when the fork is fully extended.  Aside from that, the extra was gently cable tied to the clutch line.

I'm still playing around with the calibration factor, but thus far the unit itself seems to work very well.  Visibility could be better, but it's adequate where it is.  We'll see how it is with the helmet next weekend when I go on a longer ride.

Pic's below,  dialup folks be patient, these are large.

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