I've just put new 32mm Continental GP5000's on my road bike. I ride mostly on tarmac but there is the occasional gravel or dirt trail, I've previously used the Bontrager R1's the bike was sold on on these trails with no issues.
With the GP5000's I've so far done two longer (100km+/60mi+) rides and got a flat in the rear wheel each time, both times on gravel tracks. As far as I can tell what happened was that a rock cut through the tire and tube, that started slowly letting air out, and after the pressure went low enough I then got a pinch flat on another rock.
First time I had 5bar/70psi in the tires. For the second ride, because I initially thought it was just a pinch flat, I went to the max pressure of 7bar/100psi.
Here's one of the cuts I've found on the rear tire with ~200mi/300km on the tires right now. I suspect this was caused by those gravel trails.
The trails I got those flats on had this kind of gravel on them:
To me it looks like either:
- the GP5000's are meant for the road only and gravel trails are off limits, so I need different tires
- I'm running them at too high pressures - should I try 3-4bar/40-60psi the next time?
The full weight of me + the bike + my pannier bags on these trips is approx. 95-100kg/210-220lbs.
conclusion from answers and comments:
The GP5k's are not the correct choice for the kind of rides I do and that's the main reason for my issues.
My tire pressure should be more in the 3.5-5.0bar/50-70psi range based on the Silca calculator, so I was running it too high on the second ride for sure, and at the upper end of the range on the first ride, but I don't expect that would've been the main reason for my flats (especially since the second flat I got was actually a regular pinch flat even at 7bar/100psi).
I'll ride the 5k's in the city and look at getting 5k AS TR or maybe Gravelking Slicks for those rides involving some offroading.
