Cateye Velo 9 Wired - inaccurate speed

Triathlon Forum
1

My son’s wired cateye velo 9 is showing the wrong speed. I bike alongside him with my Garmin and his Cateye is always about 4 km/hour faster than my Garmin (which i have to believe is accurate). He has a 650cc wheel size and we’ve changed the Cat eye to reflect that. Is there any other callibration i can do?

Thanks, C

2

My son’s wired cateye velo 9 is showing the wrong speed. I bike alongside him with my Garmin and his Cateye is always about 4 km/hour faster than my Garmin (which i have to believe is accurate). He has a 650cc wheel size and we’ve changed the Cat eye to reflect that. Is there any other callibration i can do?

Thanks, C

Consider measuring the actual wheel to confirm with him on the bike and tire inflated to riding pressure. I’ve taped a small string on the ground, start the valve core directly on the string and roll wheel one revolution and measure the distance.

3

If it is calibrated and functioning correctly, the cateye should be more accurate than a device relying upon GPS data.

4

650c
650c wheel circumference can vary greatly depending on tire brand, bike + rider’s weight, and inflation pressure. As already mentioned, do a weighted wheel rollout to get an accurate circumference. I used two pieces of tape on the floor, one at the start of the revolution and one at the end, and used the Park Tool R-12 to measure the distance in millimeters.