erratic speeds/ erratic power measurements

[gordo3000]

Hi guys,
I've got two running problems with my isport (I've purchased the ibike pro upgrade so I can download the data once I get a reply).

to compare, my cadence sensor is rock steady accurate.

1. I get erratic / very inaccurate speeds. I am certain, simply converting from gear and candence, that I am not cruising with minimal effort at 45+ kph (yeah, I wish I could, but those are speeds I am working my ass off for). Add to this, I have done a few rides of highly accurately measured distance and I get a significantly longer distance. my standard bike ride to work is 5.7 km and this morning, my ibike registered 6.4km.

2. I am getting very very erratic power measurements. yesterday during my fitness ride it had me chugging at 250-350 watts for the first 10 minutes... then when I started heading home, it had me between 50 and 100 watts. I don't I"m not as strong as 300 watts, even for 10 minutes, and I'm not as weak as 50 or 60 watts if I'm moving at 20 mph + in calm wind conditions.

I did do only 2 coast down rides but the cda it displays is pretty close to teh accepted level for my size (0.46 I think) and crr I just set to 60.

At first I thought the erratic signals were due/could be due to my reflectors on my front wheel but even after removing them I still have problems. I do have another sensor on the opposite side of my front fork for my old bike computer but I removed it's magnet to prevent noise. Could the sensor itself cause interference?

[Velocomp]

It sounds as if you have a wired cadence mount; correct?

Make sure your sensor is mounted near the rim of your wheel, not near to the hub. Also, make sure your spoke magnet passes very close to the sensor.

The erratic speed signal is the cause of the erratic watts.

If these fixes don't work then your speed sensor is defective; please contact Aaron Timmer at atimmer@velocomp.com