Sea Sucker

Seasucker are a Florida-based designer, manufacturer, wholesaler and retailer of great marine accessories,
bike racks and board racks for cars, and small electronics mounts for holding iPads, iPhones and similar gadgets.
The bikes are secured via the special vacuum mounted seasucker.
Each seasucker can hold up to 210 pounds each, but even more importantly there is an integrated pump with a check valve that tells you if it has lost any vacuum.
All suction cups and vacuum cups eventually lose power, theseasucker pump will slowly reverse itself and show a red line indicating it needs a pump.
You don't have to take it off and lick it, just pump it and you are back to full power.
It can take days to weeks for any of the cups to loose any significant amount of vacuum,
they do not just "release", they lose power over an extended period of time.