Indeed, there are many small air pump that can be installed on your bike, but when you need to use it maybe you have to spend more of your power to pump it because the smaller the pump then the less air that can be produced. So you may spend a long time to pump up one tire alone.
BioLogic PostPump 2.0 Seatpost
But not with Biologic Postpump 2.0, this pump does not take much energy to pump the tires to its normal state. This advanced portable pump for bicycle will be sold for $ 50.Source: thinkbiologic
