Noonievut

I was thinking of running a 700x42 tire that is not tubeless ready, and wasn’t sure about risk of pinch flats and whether tubes vs. tubeless greatly affects how plush the ride is.

I currently have 700x40 Ventures, tubeless, and run them around 30-35 (I’m 155 pounds). They grip well and feel plush over rougher terrain. I also have 38mm Barlow Pass, with tubes, run them down as low as 35mm (paved and rail trails) and they’ve been flat-free though not as plush over rougher terrain as the Ventures.

I wanted to get Soma Cazadero 700x42 and they’re not tubeless ready. I want them to run them low enough for ride quality, but wasn’t sure about pinch flats?

79pmooney

What are you riding over? That makes a big difference in the lowest pressure you can get away with. So does your riding style. Some of us are gentle to tires and rims and others of us can trash anything on that same road or path. I've run 38c Paselas at lower than 40psi on a fairly gnarly logging road for a multiple thousands of feet descent quite fast with no issues, just a huge smile. (Your weight exactly. Fairly kind to wheels.)

Try it and see. Bring two tubes and a patchkit. Start from the hard side so when you do pinch flat it's just barely and not a rim killer. 5 psi more should be perfect. (And old-fart tip. Old fashioned frame pumps, not mini pumps, make the research a lot more fun.)

msu2001la

As you're discovering - one of the big benefits of tubeless is that you can run lower pressure with minimal risk of pinch flatting. Tubes can pinch very easily, so you want to run enough air that the rim will not strike the ground.

Finding this limit will require some trial and error, and is dependent on your bike/body weight, tire size, riding style and terrain. The rougher the terrain, the more air you'll need because your tires will be compressing more as they hit rocks/roots.

I've run tubed 33mm CX tires as low as 30-35psi for training/racing and it's been fine, but I'm also aware that I'm on the edge with that setup and am careful to avoid hitting anything that might cause a pinch flat. Conversely, I run 33mm tubeless at 25-26psi and have no worries about pinch flatting, even if I'm bottoming out on big hits.

Rolla

I've used those very same Cazaderos, and got no pinch flats running them at 40 psi (170 lb rider weight). The sidewalls, however, seemed very thin to me -- and were perhaps more supple as a result -- but I never fully trusted them on shard gravel. I switched to GravelKing SK 43s and have more confidence. The comfort seems about the same.

Katzen

One of the main reasons I switched to tubulars for CX was a barrage of pinch flats at the sub 40 PSI level. In my opinion, running clinchers that low on anything other than a smooth paved road is leaving a lot to chance. I’d keep running tubeless if you’re looking to run in that pressure range.

rumrunn6

+1 for trial & error. been having fun keeping an eye on my various tires, at various pressures, over various conditions. it's funny how sometimes even a slight rise or bump will deform the tire. & of course the bigger bumps, even more-so. while I try to avoid it, I do sometimes change pressure up/down during a single ride

same pressure in both photos (nothing surprising, I know)




this was a different place, day & pressure