Pressure. Â No, not this pressure… air pressure! Air pressure can make a HUGE difference in how a bike rides, how a tire feels, and – recently for me – in how a bike test rides.
I used to run my tires more toward the max rating on the tires – around 60 PSI. Yeah, kinda crazy… especially on a full rigid bike!… but I didn’t know any better. Gradually I wised up and realized that a less-inflated tire grips better and provides a little more cushion on a hardtail or rigid bike. Now I tend to ride with my tires somewhere around 30-32 PSI – low enough to give me those advantages in spades but not so low I run a huge risk of pinch flatting or rolling the bead off the rim.
So now the story: I went out to a shop about 30 miles from me to test ride a Salsa El Mariachi 2 a couple weekends ago. Once I got out there it turned out they didn’t have the 2… but they did have the titanium-framed version! I said yes to a test ride (but “no” to buying it, the price jump was a little much for my wallet!).
On the ride, I felt the tires were over-inflated – so I let some air out. Then I let some more air out. I still felt like the bike wasn’t absorbing much of anything, so said something about it when I got back to the shop. They put a gauge on it – and it was still at 45 PSI! The guy who’d inflated the tires had apparently filled them up to 50 PSI or more. 
Lessons learned: experiment with air pressure, and make sure the pressure is the same on any test bikes you ride as it usually is on your personal bike. Oh… and don’t test ride bikes out of your price range, it just makes you sad…
Exactly, I love the lower tire pressure and went through a similar experience with over pressurized tires. I tend to run 25-30psi now on 26″ and 20-25psi on 29″ I can shed almost an extra 5psi with tubeless compared to running tubes. I do it mainly by feel at this point. If I can compress the tire by hand and touch the rim, it need more air. I’ve found I need a few extra psi if I plan on getting airborne. Don’t want to burp anything mid ride.