With the bike in the shop, I decided to go for a run yesterday and thought it would be fun to bring the GPS along to track elevation, speed, etc. I waited until I was outside before turning the unit on and gave it a few seconds to get a fix. After about 30-seconds, it didn't have a fix, but I was ready to go so I figured I'd start running and it would eventually get everything sorted out in a minute or two. Wrong.
Apparently, the Garmin Edge 305 needs to be stationary while it tries to get its initial satellite lock. Even moving at jogging speed seemed to put it into an endless search where it could never get a lock on more than 3 satellites. I'm guessing the situation was made worse by the unit being turned off where the bike broke and then turned back on again about 20 miles away (I think its optimized to re-acquire satellites when turned back on in the same location it was last turned off). Even so, you would think it would be able to get a lock on a nice clear day while moving at such a slow pace.
So, now there are 2 things to remember with this device. Don't start moving until it has a satellite lock and remember to hit the start button when you want it to start tracking your movement.