None of them. The president is too far removed to really do anything that will help your daily bike ride. You'll have better luck with local and state officials that way. Maybe.
But if you asked Obama about it, he'd promise that as president all bike riders will be living in a golden future of hope and peace, where all their rights will be respected, and motorists will be imprisoned if they are so much as rude to cyclists...just don't pester him for petty details like exactly how and when this will actually happen.
If you ask Hillary, she'll nod and make grave statements about how she supports more federal support for the rights of cyclists 100%. But she won't be able to stay long because she has a meeting with the Roads Should Be For Cars Only lobby in 15 minutes where she willl, of course, agree with them 100% too. A vote is a vote, after all.
McCain will listen patiently to your concerns, then vow to cut off all federal funding for Amtrak, bike lanes and public transportation and use the surplus money to lower taxes so that all those people he sees out there riding bikes will be able to afford a decent car, thus solving all their cycling problems.