Lol, I thought that was a joke question. Well, from the first anime I ever returned as a teenager for being to ecchi here's Golden Boy 5. There are other pics and one of them may be what you were looking for. She's from the episode "Balls to the Wall" according to
wikipedia.
As you are looking for an older image, that series is definitely old enough. It could also be any one of the Gantz covers which usually feature cg girls and bikes. I can understand though. Some images just stick with you forever. These ones stuck with me;