Inaccurate speed

[acevans]

I recently purchased the iPro Gen III. While I have not yet done the coast down or calibration ride, I am getting really high speed readings from my unit. I would guess these are at least twice as fast as true speeds. For instance, on a ride today, the software analysis shows an average speed of 28.2 mph and a max speed of 100.7 mph!! The moment to moment values on the unit's display are correspondingly high and quite unbelievable. I have tried re-pairing the speed sensor but no difference. Put in a fresh new battery in the main unit and had the same problem. Cadence appears accurate. Wattage is also very high (average 395.6) but given the inaccuracy of the speed and the lack of coast/calibration I'm guessing that can happen. I have double checked my wheel circumference and have re-entered it--no improvement.

Has anyone else had this problem? What should I try next? I haven't changed batteries in the speed sensor since it is brand new with a brand new battery.

[pjboyle]

You might try moving your magnet slightly or even rotating it 90 degrees around the spoke. A magnet has a north and south pole and the field around it looks like an hour glass (three dimensional figure 8). In some cases the sensor can pick up both lobes of this field and double count each pass of the magnet.
PJBoyle

[Velocomp]

Make sure your sensor is mount closer to the rim of the wheel than to the hub. That gives a more precise magnetic pulse. Also, make sure your magnet passes close to the sensor. Finally, make sure there are no other magnets "in the neighborhood" that might interfere with the speed sensor magnet.

[bex]

I had a similar problem until I realised/remembered the difference between circumference and diameter!
Fixed in a jiffy, DUH!
I cannot believe I even posted this!
Indeed, I kind of hope yours is a more complex problem than mine was, just to save the embarrassment!

Bex

[acevans]

Thanks...I did both the magnet rotation and repositioning toward the rim. Working fine now. Thanks again.

Suggestion: Maybe put the tip about the location close to the rim in the owner's manual. I looked before I installed it and didn't see that tip. Makes a lot of sense to locate it there. Anyway, if it is in the manual I didn't see it.

I love the device and have been very pleased with Velocomp's devotion to the product and customer support.

A.C. Evans