This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.
Because I am on vacation, I am not going over to Europe to suffer on every
climb, so being in shape is of tantamount importance. Plan your pre-trip
riding depending on the type of trip you are going to do. I live for
switchbacks so I go to Europe to ride the passes, so I try to do a lot of
climbing on my rides in the US.