August 3, 2015: I have started to assemble a BOM. The key to a sensor like this is a pressure sensor IC that is small, cheap, and can go up to at least 100 psi for bike tires. Unfortunately, these criteria make the selection pretty thin. I found two candidates: The Nova Sensor NPP-301 and the TDK C32 family. Both are Wheatstone bridge designs and will likely need to be amplified. The TDK sensors are much cheaper, according to Digikey, so I will plan to design with them. http://www.digikey.com/product-search/en?vendor=0&keywords=B58600H8400A038

Unfortunately, none are in stock.