I will switch sensor 1 to shock, 2 will be front tire & 3 will be rear tire. Biggest issue so far is because high pressure alarm setting maxes out @ 99psi ( I think but am working on solution ) so as your riding and the rear shock compresses / rebounds the psi changes which set off the alarm so with every big bump the monitor will flash letting you know the psi changed ( is pretty constant changing with an air shock ) the audible alarm is present but you can't hear it unless the bikes off, no helmet & is zero background noise, the screen flashes from regular blue to red grabbing your attention without hearing the beeps if goes beyond 99psi ( my set perimeter) Am still very pleased with system. I noticed riding into work just now that while solo the shocks sensor will flash as pressure changes with every compression / rebound of suspension stroke but solo it doesn't exceed the 99 psi perimeter so doesn't flash red, it still will flash alerting you that the pressure has changed. My 2 days worth of hind site is to only buy the 2 sensor system, you'll immediately feel the difference if the rear shock suddenly looses air pressure ( is also unneeded if you have a Penske ). A third sensor on the shock is only good for reading the preflight psi & is pretty much useless while moving on anything other than glass smooth surfaces esp if your 2 up & loaded dwn.Wonder if it would be better to have your tires the two trike rears (since they are similar) and the shock the "front" since it is vastly different. That way, your alarm could be set closer to what pressure you actually run and could be an earlier warning sign if anything g happens.