yes, it's a footpod issue tied to the FR305, on the link I sent above, one of the comment is:
Regarding Question 5
Reviewed by: Donovan Watts, Dec 29 2010 6:03AM
Just a quick comment regarding question # 5 with respect to the cadence being cut in half. I spent about fourth months trying to resolve this with Garmin tehcnical support. We tried changing batteries, new foot pods, and a new garmin. In the end it was found that the latest software revision on the Garmin 305 did not work correctly with the foot pod.
I will try to load an older firmware(2.8) and see if it will fix it. I hope Garmin releases a new firmware to fix the problem.
Regarding Question 5
Reviewed by: Donovan Watts, Dec 29 2010 6:03AM
Just a quick comment regarding question # 5 with respect to the cadence being cut in half. I spent about fourth months trying to resolve this with Garmin tehcnical support. We tried changing batteries, new foot pods, and a new garmin. In the end it was found that the latest software revision on the Garmin 305 did not work correctly with the foot pod.
I will try to load an older firmware(2.8) and see if it will fix it. I hope Garmin releases a new firmware to fix the problem.