If you're going to use gel tape under your bar tape, make sure you don't leave it under the bar tape for too long without an occasional check on it's condition. Here's a link for a thread on another cycling forum that shows what happens to gel tape if left unchecked.
n-a-s-t-y-cable-maint. The gel tape was put on the bike by the previous owner and the new owner bought the bike to as a trainer bike. He went to replace his cable set and ran into a mess caused by the gel tape.