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"Genius" was about a boy who invented an anti-gravity machine, but I don't think it was in the form of a bike. You may want to check this list if you haven't already: http://en.wikipedia.org/wiki/List_of_Disney_Channel_Original_Movies
Ahah! Found it via a Bing search that linked to a Yahoo answer. Ask Max
starring Chunk from The Goonies. It was produced by Walt Disney Television, but apparently was not one of their DCOM properties. Out of five reviews, there seem to be 3 massively positive and nostalgic and 2 saying that it stank. :) Honestly, I don't remember... and apparently it's kind of tricky to find the movie anymore.
Edit: And apparently not as difficult to find as I thought
. "Disney Sunday night movie" was the promotion that aired it.

OK, this time I did more research and still failed to find anything. Looking for a Disney movie, probably around the 1980s to 1990s, involves a kid who finds a way to make his bicycle jump, I think using hydraulics, by pressing a button on the handlebars. There's a section where he proves it on a horse-jumping course. He sells the idea to the company and gets a lot of money for it, but finds that the money doesn't make him popular (there's a section where his mother is consoling him after his birthday party, complete with a laser show, smoke, and maybe Michael Jackson, where no one came.
Near the end of the movie, he realizes that he made a mistake about selling the invention and so he pulls out his original bike and rides across town using its jump ability to... do something. I don't remember exactly what.
I remember it being aired as a Disney movie (there used to be a standard day of the week and time when they showed them) with little commercial bumpers involving people in the character suits. I believe that Goofy pulled the bike out of the crate and somehow wound up floating into the air with it.