Muscle through them.
That could work during the training periods.
Loud horn too. More than one? A funny sounding one (ooUH-ga) and one more like a train.
If there was a passenger on the motorcycle, then have them carry a super-soaker water gun. That could be fun. Hell, on a hot day the bicyclists might even thank you.
If you want a loud horn, this is an option: http://www.amazon.com/Stebel-Nautilus-Chrome-Compact-Motorcycle/dp/B003SEBYF0