I had my first significant puncture of the year on my rear tire. I’m running 28mm tubeless GP5000 with Orange Seal. The puncture sealed up and when I felt the tire, it was soft but seemed to hold my weight without deforming too much. That said, when I continued on the ride I was surprised at how I couldn’t hold speed on a familiar descent and powering up rollers felt more difficult than usual; for example I usually go about 40 MPH on the descent with minimal power, this time I was pedaling relatively hard but couldn’t get over 34 MPH.
When I got back to the car I check the tire pressure and was very surprised to see it was around 35 PSI . I’m 99 KG and normally pump up the tire to 90 PSI. Yes, in retrospect it was very stupid for me to bomb a descent on a soft tire but at the time, it didn’t feel super soft at the time.
The rim seems undamaged, thankfully, but I’m curious as to what the “cons” are for running a tire that is too soft. I know the benefits are a smoother ride on rougher roads and better handling in the rain, but do softer tires have more rolling resistance or is that just in my head?
EDIT: I’m not planning on running my pressure that low on purpose, but if there’s no effect on rolling resistance then maybe I’ll reduce the pressure to 60 PSI.
I’ve ridden home on a completely flat rear tire, over 5 miles, albeit at a slow speed. GP5000 tire on a Roval CLX64 carbon rim. No issues after I swapped the tire.
Your wheels are fine. You’d know if they’re not (wobble wobble).
Main issue = tire coming off the rim during a turn.
I’m about your size, and did this with a 28mm tire that I didn’t realize had gone quite so low. Lost all air pressure from the rear tire in the corner and down I went, skidding across the pavement.
I wouldn’t feel bad for going hard, shirt happens sometimes. And having 35 psi left is certainly better than flatting entirely, which would have been your fate with inner tubes. And carbon rims are not that fragile. Just inspect them for damage or wobble. But in all likelihood they are fine.
Recommended tire pressures have significantly decreased over time, especially on wider rims and when you are running your tires tubeless. But they depend on a lot of factors, including rim width, tire width and rider weight. If you look at Enve’s recommended tire pressures or Zipp’s tire pressure guide, you see that even at your weight Enve recommends 65 psi if you were on their AR rims, 77 psi if you were on their narrower rims. I have 3T carbon wheels with 25 mm internal width (3T’s equivalent to the 4.5ARs) and run 55–60 psi (at 74 kg), which is roughly in line with the recommendations by Zipp and Enve. That feels great on the road, my tires are glued to the tarmac without feeling draggy in the slightest. Like you, I run tubeless. I’d definitely not run my tires at 90 psi any longer, that’s for sure.
Thanks for the links to Enve and Zipp. I’m running Roval C38 rims which are 21mm internal width, so yup, 77PSI looks like the ideal pressure but I’ll probably run them at 80 for a bit of fudge factor. And yea, 30 PSI definitely felt draggy (or I was just sucking today).
I’d definitely experiment a little with tire pressures. For example, I run slightly lower tire pressures when it has rained (Zipp’s tire pressure calculator asks you for the conditions). I basically trade grip and safety for rolling resistance. The ideal pressures for you also depend on the tire you pick.
. I’m 99 KG and normally pump up the tire to 90 PSI. Yes, in retrospect it was very stupid for me to bomb a descent on a soft tire but at the time, it didn’t feel super soft at the time.