MrTri123 wrote:
How much would tire pressure change from say 70 degrees to 95 degrees?
Rule of thumb is about 1 psi for every 10 degrees. For a road/TT bike, that's nothing. For gravel or MTB, it's not much, but it is something. As Josh has explained in the Marginal Gains podcast, a few PSI in a race on cobbles is the difference between the fastest possible setup and two broken rims.
For MTB and Gravel, I think the TyreWiz is somewhat useful. On training rides or preriding a course, you can stop and go as much as you want to inflate with a handpump or deflate until you find the pressure you really like. You can also do this with a portable gauge, if you want to save about $175. I really like my accu-gage, and it reads within about 1psi of my Silca Superpista Digital
On race day, a small puncture is often sealed with a good sealant, but often times some pressure is lost. Maybe I'm not attentive enough, but often times i don't even notice when this happens. I just keep riding. The Epic in Missouri a few weeks ago was an example of this. I set my pressures before the race. In the second half of the race, I felt my rim hit rocks a few times. I told myself that next time i need to start with a couple PSI more. However, after the race I checked my pressures again, and they were about 10 psi lower than when I started. I must have had a small puncture at some point. I was lucky I didn't snake bite my tire and lose all the air, and a lot of time. If I had the tyrewiz, i would have known i was 10 psi down. While riding i could have gotten my CO2 ready, then hopped off my bike, gave it a quick shot of air, and chased back on in almost no time at all.
It's a niche product. If you don't understand why somebody would buy it, then it's probably not for you. For road riding and triathlon, i think it's near pointless. For offroad use, it has a purpose...you just need to justify if the data is worth it to you.