I've always thought of making a bike poncho. One that fits over the entire top portion of the bike, including the rider (cyclist). However, when you dismount, you just unzip the poncho and step out. Once you're out, you zip it back up and lock it to the bike. In order to ride the bike, the poncho has to either be legally unlocked or illegally cut.

When it's time to leave, you unlock your poncho. You step inside of the poncho and zip it back up, over your body.

- Slim