The Ping duct tape battery is still performing well after 2526 miles and 221 cycles. I have found the bike is a little bit slower (voltage sag) if the battery is very cold (below freezing out), but I think this occurs with many types of battery. The rough roads that I take to work have destroyed two previous aluminum rear racks, which made me decide to go for home-brew tubular steel and all-thread. This homemade rack has worked out much better than either of the other commercial racks that failed previously. The battery is also much more stable with a lower center of gravity.
