Pinch flat after 600+ miles on same tires

DDRider62

I have not had a flat for a while. I bike (or used to) most every day, about 30 miles during the summer. From July 30 to August 20, I biked 600 miles, and pumped up my tires whenever I found the air a little low (normal air loss tires go through) 4 times. One of the 4 pump ups in those 20 days include August 20: the morning of my last ride.

I went out to bike a hilly 60 mile route (about 4800 ft. ascent) with a friend. In mile 40, going downhill on a road, at about 35 mph (according to my GPS unit since I don't remember anything), I had a pinch flat. How do I know? The tube has snakebite marks on it. The tire was pumped up to 115 psi that morning, so I am sure the tire was not low that day. I weigh 175 lbs. Somehow when my tire exploded, I lost control of the bike and I fell. As I said I don't remember anything. I know I was biking uphill fine (don't even remember the downhill part), and woke up at the Intensive Care Unit in Harbor View Hospital in Seattle, which is the best trauma center there is. The fall was bad! I am very lucky to be alive. I spent 5 days at the hospital. A little over a month has gone by and I am still recovering from traumatic brain injury (yes, I was wearing a helmet, which appropriately saved me and broke). Luckily I"m doing much better, and should be back to normal in a matter of weeks.

My wheels are Fulcrum Racing 5 LG, on a Cannondale Super Six EVO bike. The tires are Schwalbe One, and they have been used a lot, but are still in good condition. I checked the rim tape, and all the spoke holes are properly covered. It's the original rim tape Cannondale put on the bike. It appears to be in good condition. I use 700 x 25c tubes.

OK. Now the questions:
1. Can someone explain in detail the snakebite flat? I don't understand how the rim would cut the tube. It makes more sense in my mind that the bead border in the tire would press the tube against the rim so hard that it would cut it. I found nothing very detailed online about how it happens. I want to understand more. Are the 2 cuts from the snakebite mark the same cut on 2 layers of tube, or are these 2 independent cuts, one on each side of the rim (and hence the tube)?
2. Why a tube that has been going fine for over 600 miles, pumped up multiple times to the proper pressure without ever losing a lot of air, will suffer a pinch flat after I biked so much (including a full RSVP ride from Seattle to Vancouver, BC the week before), and many other rides including several at about 100 degrees Farenheit? Does this even make sense?
3. I need to learn how to avoid snakebite flats if possible 100%. Based on all I am telling you here, I feel like going downhill with my bike and reaching over 20 mph becomes a game of Russian roulette. If the pinch flat happens in that moment, I'm basically done, and might wake up in a hospital again, or even worse scenarios I don't even want to consider.

Please provide me with reasonable information and advice. I hope this story will help me, and prevent others to go through the same awful experience. Should I change to tubular tires? Are they completely snakebite proof?

Thanks.

sloppyschleckonds

Sometimes in life there are no answers to the questions we pose.

Thank god you lived to be able to type all that.

Maybe investigate using tubeless or tubulars. In my experience tubulars never fully deflate so a lifesaver.

Good luck

redbikejohn

When I got my new giant I had a few pinch flats from hitting broken up road surface so I bought some conti tyres again. Mine is most used to commute to work three time a week but it a 50 mile round trip at odd shift times so I can't afford to be late with a puncture so I bought some Continental GatorHardshell Road Tyres and pump them to 100psi. They have been fine for months now.
Snakebites I found to be two small slits on one side of the tyre or one either sides - it tends to vary ! It could be possible that there was a small loss of air due to a tiny puncture or a valve leak from pumping it up earlier and that lowered the pressure enough for the failure. All the best with recovery...

pblakeney

You do not get a pinch flat on smooth tarmac.
You hit either a pothole or an object. Avoid those.

First.Aspect

A pinch flat is two cuts either side, where the rim wall cuts the tube.

You've been unlucky, but I cant see how you can attribute it to anything other than luck.

You can get a slow puncture at any time, which can then lead to a pinch flat. I don't think there's anything wrong with the tyres.

In that case you just learn to sense the bike feeling different.

Alternatively you might look at bike handling. On a descent there shouldn't be too much weight on the front of the bike.

Bigger tyres and wider rims help. As does tubeless, I'm told.

Main thing is to recover and then decide if you still want to cycle. There are lots of things that can go wrong when you are skimming over tarmac wearing what is basically underwear. But it doesn't happen that often. I personally find that act of god events are easier to rationalise than when I've just fucked up myself.

feisty

Road tubeless would avoid pinch flats and, if you were to get a puncture that was too big to self seal, the air pressure should go down much more slowly.

But if you hit a pothole (possible if you can't remember) that could throw you off bike anyhow so nothing is 100% safe.

Thankfully you are ok. I'd just ensure you are careful on descents. Were you to want greater peace of mind then road tubeless worth investigating. I have them on my commuter and been great. I personally find the ride a tad firmer so don't have on my best bike but that's just me. Others say they find them just as comfy.

feisty

Ps. You probably know this but tubular and road tubeless are different. Road tubeless is my suggestion for regular (non racing) riding were you to move from clinchers.

fat daddy

I agree with the above, you hit something .... a decent sized pot hole at 35mph can easily compress a tyre to the rim even at 100+psi

I have managed it at below 15 mph on the flat whilst not paying attention to the road surface .... at 35mph, I imagine even a rock in the road could do it if the rock didn't ping out the way

sloppyschleckonds

OP hasn't said if he was wearing a helmet or not

fat daddy

yes he has :--(yes, I was wearing a helmet, which appropriately saved me and broke)

fenix

Glad you are recovering - but I think you're overstating the risk. A flat tyre does not automatically send you crashing.

You were unlucky to get your flat for starters and even more unlucky for it to send you crashing.

I've ridden 35 years and not crashed due to a flat.

That includes a double blow out on tribars in a pothole and a front tyre blow out descending an Alpe.

stevie63

Just to add that whilst tubeless tyres wont pinch flat that doesn't mean that they can't suffer failures. A couple of weeks ago the sidewall of my tubeless tyre exploded but thankfully I was only going slowly at the time so I was able to bring the bike to a safe stop.

joe2008

stevie63 wrote:

Just to add that whilst tubeless tyres wont pinch flat that doesn't mean that they can't suffer failures. A couple of weeks ago the sidewall of my tubeless tyre exploded but thankfully I was only going slowly at the time so I was able to bring the bike to a safe stop.

I like the reassurance that my tyres are stuck to my rims with glue.

keef66

Firstly, hope you have a speedy recovery!

Even with a brand new tyre and tube inflated beyond 100 psi, if you hit a pothole or some road debris with a sharp edge it's perfectly possible to get a pinch flat. I only weigh 140 lbs and I've done it several times at speeds from 10-30 mph either due to inattention or hitting potholes disguised as small puddles while night riding. Never thrown me off the bike though; they usually take a few seconds to deflate and having hit the pothole I'm half expecting the flat and may be already braking.

My only instant blowout was fortunately on the rear. Something sharp sliced right through the sidewall of a brand new tyre, and the tube just exploded. The bang sounded like a rifle and scared the crap out of me; doubly so since I was descending at 33mph according to Garmin. Suspect I might have crashed had it been the front tyre.

DDRider62

Thanks for all the answers so far. The more informed I can be on the topic, the better prepared I will be when the time comes to bike again (spring of 2017). I appreciate all the responses so far, and read all with high interest and attention.

tgotb

Even tubeless tyres can pinch flat; they just do it less easily.

On the road, you can pinch flat when your tyre is getting soft (possibly due to a slow puncture) and you hit a lump or small pothole. You can also pinch flat a fully-inflated tyre if you hit a pothole hard enough.

I've pinch flatted a 130psi front tyre (clincher with tube) hitting a pothole in a time trial. I managed to pinch flat both tyres (130psi) riding up a kerb at 30mph. I also pinch flatted a tubeless CX tyre, riding over a very small kerb at ~20psi and <10mph. No setup is 100% bombproof, the trick is to avoid riding into/over things as much as possible :-)

de_sisti

DDRider62 wrote:

Thanks for all the answers so far. The more informed I can be on the topic, the better prepared I will be when the time comes to bike again (spring of 2017).

What? No winter riding?

pblakeney

FWIW, if your tyre had been deflating enough for a low pressure snake bite then you should have felt it at the previous corner. Even an instantaneous blow out is controllable for a few seconds. Enough for a serious incident suggests impact.