An OCWSatCentury group ride organized by Chuck Bramwell. I coaxed Judy and Allison to join the ride; they were up with the faster, lead group when I stopped to take off my vest, and a middle group which included Margaret, Molly, Vic, Daniel and a couple of OCW riders went by. I caught up with that group and one of the OCW riders erroneously called out a left turn that took us off route at Lakeview Ave (mile 15). My Garmin sounded the alarm, and Chuck Bramwell's group, which was a little further behind, called out that we were off route; I chased down the other riders and we all turned around and took the river trail outbound., which I think is a nicer route (certainly more scenic). We stopped at the first water stop, and the OCW riders skipped it. We spent significant time at each of the rest stops, and we also stopped to work on a mechanical that Molly suffered which prevented her from being able to shift into her large chain ring. Vic eventually was able to fix that problem. As a result of the stopped time, though, we never caught up to even Bramwell. Still, it was a nice day of riding, if a little on the cool side. Between being off route and on the river trail, my Garmin began acting up and was directing me to take many wrong turns, and I led us on several wrong turns, but someone else quickly caught each mistake. I reset the Garmin a couple of times and it continued to act up until near the end of the ride. I think that, when Garmin crashed and reset itself, it changed to a default setting for recalculating the route, which needs to be turned off. The out-and-back sections of the route may also have contributed.