Looking for some advice.
I moved from using 38mm GravelKing SK's with TPU tubes to 30mm P Zero Race tires.
I never had a flat with the SK's but I'm doing more group rides this winter and less light gravel rides, and wanted a speed boost.
My First ride was 20 miles and fine, but got a pinch flat as soon as i hit my drive way.
my drive way is a moderate incline certainly not flat, and a mild transition from the road.
At first i thought it was because i reused my TPU from my 38mm tire, so i used my spare (also 38mm tpu) and it did the same thing immediately hitting my drive way. ( snake bit 2 sharp holes)
This was confusing for me because i did go over speedbumps and roll off a curb at my coffee shop on my route without issue. But my drive way apparently hates the combo.
I'm using Butyl in the rear for now, the front tire has held up, but have ordered TPU in the right size to try it again.
I'm running 85psi in the rear and 78 in the front.
Is there a to installing them wrong, should i just know i need to unweight or dismount prior to my drive way? (nothing real sharp just a slight lip before the transition from road to driveway).
If they were the tires out of your 38mm they will be too wide. Tpu stretches and doesn't unstretch. So you can't swap between tire widths.
I may have misread but if the spare was not new, same issue.
Otherwise I don't know.
Ok I am super confused which happens at lot for me. Clarifying, you went from 38mm gravel tires now to 30mm road race (p zeros) and you are running at 85psi, doing wheelies over speed bumps and jumping off curbs?
Ok i see how thats confusing.
I roll off a curb at a coffee stop, and pop over speed bumps without issue.
But gently rolling into my driveway causes a snake bite.
So I had similar using butyl tubes when I first started riding a road bike with 28’s after years of commuting on plush 2-2.5” tires. When I came into my driveway it had a short but sharp step, maybe 1.25-1.5” tall. Often I was at an angle as I banked into the driveway. I used to be able to plow over this with ease, no issues. With road tires I got a few flats, simply too sharp and edge given how I was sitting on the saddle with usually tired arms resulting in locked elbows.
If I came into my driveway more head on, shifted my weight back and kept my arms slightly bent the front would roll over easily, and then I would shift my weight forward as the rear came over with knees bent and butt out of the saddle I had no issue. So be mindful as you roll over, don’t be sitting down or stiff arming the front as you hut the edge.
Ok right on. I feel like 85psi is way too high for 30mm hooked or clincher road tires with TPU tubes. I run my 30mms at 67psi but I weigh almost 100 kilos. Are you sure they arent blowing out? Have you run a pressure calculator on that setup? Especially those "RideNow" tubes for me I have found can be sensitive to overpressure. Why it happens at your driveway more often I am not sure.
Yea im quite a bit heavier.
Rechecking silca, says 75 rear 72 front. Ill give that a shot.
I used that one and sram before and went with the higher one.
Ah right on. The only thing throwing me off is the snakebite puncture you mentioned which does sound like pinch flat and not a pressure blowout. I think Silca and Wolf Tooth and Pirelli's calculators will all put you around low 70's which sounds about right if you are much heavier.
Wait you're running 85psi on 30mm tires and hitting curbs/speedbumps? That's asking for trouble right there. Those TPU tubes are way more sensitive to pinch flats than butyl, especially when you're basically riding on rocks with that pressure. Try dropping to like 70-75psi and see if your driveway stops eating tubes
Just as another data point, I run 28-32mm Ridenow metal stem TPU tubes at 60psi rear and 55 psi front on Bontrager Aeolus Pro 37 rims with Pirelli Zero Race 30mm.
Combined weight 76kg.
My driveway has a shallow lip which I ride over and I’ve never had any snakebite punctures but I don’t do wheelies!
lol yea i think i oversold that part, just popping the front wheel over a speed bump lol
Try using the correct size TPU in your P zeroes. My experience with Pirelli tires is that they run narrow, and so using a TPU tube that was in a 38mm tire means you're definitely using the wrong size tube. It's possible that when fully inflated there are some folds in the too-big tube, and maybe that makes them more vulnerable?
So many of you people underinflate your tires based on sketchy advice from the internet then you get problems like pinch flats and wonder what went wrong.
Also in my opinion these 'tpu' tubes are too new a technology for bikes to really be more than an experiment, meanwhile there's little advantage to using them especially for the casual/amateur/commute riders compared to traditional butyl rubber tubes.
You’re contending that 85 psi in 30mm tires is underinflating?
What's the minimum pressure stated for the tire in question?
Also what do you weigh? If you're a big guy you need more pressure.
Regardless of all that if you're getting pinch flats for no damned good reason then your tires are underinflated.
Tubeless exists, use it