Found the pressure limits of my Clement MSO s
 

With the ridiculous heat the past couple weeks I didn't get much riding in, and in that time my tires lost a little pressure. Yesterday's ride I kept getting a sensation that the bike was oversteering as well as a feeling that maybe the tires were starting to roll under and lose stability. When I checked my air pressure after the ride I was at 20 PSI. So if you wanted to know how low you can run 40c MSOs with tubes, it's probably around 30 PSI.

I've run them around 25 PSI, but I can feel rocks a bit more than I should. If for some reason I need to take it to a bike shop, they always inflate them until they are rock hard and then give me a lecture about how un-American and incompetent I am for having squishy tires.

bcpriess - did the same thing with some 32mm tires. They were at 30psi, bottomed out easily, and started to wash out under slow speed sharp corners. Then again I have some 54mm tires that tend to wash out under 30psi too. They feel really weird when the sidewall caves in, than snaps back into place.

wgscott: that is funny. Too old school. But I'm sure they have years of experience of people bringing in poorly maintained bikes and complaining. Tire pressure is one of the easiest and most neglected maintenance items.

^Yeah, I weigh about 190lbs and I find ~32 psi to be the bottom of the barrel on 33mm tires, but man do they sure ride nice on grass at that pressure

When the tire company said inflate to 50-70psi, i will inflate my tire to 50-70psi.. and when someone tells me that i should under inflate my tire for comfort, i say "screw you".
only been to gravel grinding 3 years. My first year All my flats were because of pinch flat due to under inflation. Lessons learned all my tires now even the 40mm are all rock solid to 50 or plus psi- flats been 0 so far.

I've found 40 to be my sweet spot. Soaks up everything, still roll fast, no instability.

I don't feel the need to tell people to go screw themselves over tire pressure.

I like to run my tires a little squishy. It can feel a little unsettling on the road, but on gravel, no problem. With a tube, I expect 20 to be a problem for pinch flats

Just did this too.

Aired out my 33 Clement LAS's last night to ride on our cross course. Went a little too far and ended up around 20 psi. Felt awesomely squishy on the rough stuff and hooked in corners nicely but just a little too floppy for comfort.

Tubeless ready rims + tubeless ready tires + the lowest pressure that doesn't feel squirmy = happy gravel riding.

Ages ago when I was in college and riding my MTB everywhere I once had a slow undetected leak in the front tire. Instead of 30ish PSI it was probably at 15 or 10. I found out the hard way when I rolled down a curb, the whole tire caved in to one side, and I went over the handlebars the other way. Lesson learned. Thankful for full-finger MTB gloves (I completely destroyed a pair that summer, fortunately with no injuries, but that's a different story)

I'm thinking of doing my first cyclocross race sept 10th in chicago. With tubes and 33mm tires..what's a reasonable pressure for a 190lb guy? 40-50 psi? I'd rather be safe and finish the race without pinch flats than try to eek out a bit extra performance. I have no idea what I'm doing lol.

If it was me I'd start at 50 and adjust from there.

So much depends on rider weight, rim profile, the characteristics of the tire itself, and probably a few other factors I'm forgetting or unaware of, you just kind of have to figure it out.

FWIW before I upgraded to tubeless, I squirted some Orange Seal into my tubes (only works on tubes with removable valve cores) and was able to drop about 5-10 psi without pinch flatting. Kind of a poor man's tubeless (although ghetto tubeless is actually a different thing entirely but I digress).

Fair enough. Yeah this is my first cyclocross race, so I'm not too interested in getting super involved as far as gear goes. I anticipate I'll probably crash on the first turn and cause a pileup anyway lol :cry:

I actually stopped by the race at this course last year as it's right in my neighborhood..and thankfully it does not seem all that technically involved. Tubes with 50ish psi I think sounds reasonable...maybe I'll throw my cyclocross tires on next week and do a couple 1 hr sessions in the forest preserve per week and just do intervals with switchbacks. Quite curious (terrified?) about how I'll fair. I just started doing a couple group road rides in the last month, and I was able to hang with the faster riders in the group, most of whom have been doing competitive cyclocross for years. So...at the very least, I hope my power output will be more than adequate for cat 4/5. Who knows. I suppose I don't mind being DFL my first race as a 38 yr old haha.

dfl > dns

dns > ddtahbc (Died Due To A Horrible Bike Crash) :(

LOL true but that's probably not going to happen going 10-13 mph on dirt. Not saying it couldn't, just unlikely.