Couple ideas....

1) Kill the freakin' ant mound near where you park.
2) Spray the underside of the bike with "Ortho Home Defense".  It's fairly odorless and doesn't hurt paint (at least not my baseboards in the house).

There are only 3 points on the bike that they can climb up on the bike from - front tire, rear tire, side stand.  Spray the tires and side stand with Home Defense.

What is it with ants liking electrical stuff?  For whatever reason, the little bastards like the electrical panel on our outside AC condensing unit.  I have to fight the little assholes all summer.

You can park your bike on a verry hairy carpet. That will stop them. And sprey the carpet whit poison.