Just received the cadence sensor to use with my forerunner 305. I used the ‘auto’ function for the wheel. It gives you the option to do the roll out and put the wheel size in in mm, as you would with most cyclocomputers.
A few questions: 1. how does the auto function work (and does it work with 650 wheels) 2. has anyone used this combo and found any problems with speed accuracy using the automatic calibration? 3. How does the GPS speed/speed sensor speed work together? Does it just pull from the sensor once installed and realtime speed only comes from the sensor or does it somehow correlate/average with the GPS position and the speed sensor at the same time?
I don’t have one, so I can’t tell for sure, but I remember somebody saying the speed portion of the GSC10 only kicks in when the 305 can’t get a satellite signal…like when you are on a trainer in the basement.
Victor
The auto-calibrate bases its calibrations on speed/distance data received via the GPS signal. Therefore, when using this feature it is best to make sure you have a solid sat lock before starting your activity. While you are riding, the unit continues to take readings as long as there is a GPS signal and computes what it believes the best figure is for your roll-out. This feature will work with whatever wheel size/tire/air pressure you have. That said I myself feel more comfortable programming my figure in directly (not that I have found this feature to be inaccurate–I’ve left a cheap cateye on my bike as a backup and want my figures to match). As has been said, real-time speed only comes from the sensor when the GPS signal is disrupted or turned off.