i still have not had a chance to do a roll-out measurement yet because it has been so crappy out and i have been feeling a bit sick but i think i have it fixed. i moved the magnet and pickup closer to the hub and it seems to have corrected it. now when i walk my bike it says 5km/h. i don't have a GPS unit so that is not an option. my guess is based on the fact that the average person walks at 5km/h