If this item works like similar products for the RV industry it should be reading real time and if you mount it on the bars you will have almost real time display.
I say almost because typical RV units broadcast the pressure about every 5 minutes - unless there is a pressure drop, then it is immediate.
The video below is from a tire pressure monitor I bought in July of this year. It monitors my 4 truck and 4 trailer tires. My trailer is 18,000 pounds and "had" what is known as "china bomb" tires. Tire condition is a concern

The unit will scroll between all the tires and jumps to whatever sensor broadcasts it's signal, then continue scrolling. My particular monitor also monitors temperature.
In the event of excessive pressure, pressure drop (couple of PSI) or excessive temperature it switches to the alerting position and displays as below.
3 weeks after buying my monitor I had a tire fail. The monitor alerted me when the pressure was down to about 74 psi (from 80 psi).
Gave me enough warning that I had time to find a comfortable place to pull over and change the tire.
Since it is almost real time it also saves me from having to "gauge" the tire pressure in the morning before heading out for the day