Chandne

So I was coming down Vail Pass and it is a really twisty section, and basically hot a corner too hot. So I touched my brake to scrub a little speed but was still leaned over...I did not straighten up. Unfortunately, the rear brake was pressed a bit hard ( I really need to switch to Brit style) and I heard the tire slide just a bit. No big deal, I thought. I slide corners on the MTB sometimes. Yeah, not the same. At that second, the sidewall blew out, I went down super fast, bounced on the asphalt, slid a few feet, and thankfully went into the dirt right after so my skin loss was not high.

Anyway, there was some bleeding and road rash but all seems good- nothing broken on bike. I tried to change tubes but the tire hole was huge and so I put all I had- an empty gel pack between the tire and tube. The hole was bigger than my thumb and tearing apart it seemed, so I only put in maybe 30-40 PSI since higher was causing the gel pack to bulge out.

I then limped to the next town over maybe 14 miles away and kept my weight mostly on the front. I had a 5-6 mile climb and decided to not try it on that tire, so I managed to find the free bus line and it took me home.

I learned two lessons- don't hit relatively unknown corners so hot, and don't brake at all while leaned over. I believe the sidewall abrasion caused the blowout. I was using tubes with Conti GP4000S tires. Tires are relatively new. I don't have my proper iPhone charging cable today and am out of town. I'll try to upload pictures tomorrow, unless I figure out how to do it to Photobucket via my phone and then post the image link.

nycphotography

I'd be checking very carefully for brake rub.

Do you drive your bike to the ride? Any chance the brakes got bumped?

The fact that a "fairly new" tire blew right when you were cornering is a coincidence... and most coincidences aren't. They usually suggest that you haven't yet quite figured out exactly what happened and exactly why.

NYMXer

You said that you Mtb, so you should be very familiar with the term "brake modulation". It works on the road bikes too.
Glad that you are not seriously hurt and the bike is fine but mostly glad that you made it home safe and learned a few things so that it doesn't happen again.

kbarch

Sorry about your crash, but sounds like you're OK.
That's convenient!

See, that's a lesson I don't have to learn. Even on corners I've been on dozens of times, I'm still super cautious. I'm most comfortable when I can see for miles.

Chandne

Yeah, I was probably a little too leaned over at the time. This happened around 25 miles into the ride. It is possible the tire was defective but I think it was because I slid a little and it abraded the sidewall enough to cause the blowout. It was likely what we call "user error" and I agree about modulation. I do still sometimes get confused by the right-rear and left-front thing. I grew up the reverse way so that stick in my head. It is hard to be 100% sure about the exact cause except I went in hot and hit the rear brake to hard. The brake was a bit skewed but I feel that was caused by the crash and not the cause. I'll post a picture or two soon.

Chandne

Oh, the bus system is freaking amazing...bike racks in front, all free, and they run every 10-30 mins depending on where you are. I'm floored by that. The driver was quite concerned, though he prob was just worried about me bleeding in his bus. I wasn't by then but he could probably see the red skin. That may have been the highlight...the bus situation.

nycphotography

I seriously doubt it's possible to abrade through a sidewall and blow out a tire by over braking in a single corner.

I had a blowout in the mountains (ironically, a front range trip) and it turned out to be the brakes rubbing.

turns out a mountain descent may be what it takes to get a sidewall good and hot so it will blow.

otherwise, the brake just tends to rub a little without blowing out the tire. at least that's what the shop told me later that week, ie that my brake may have been rubbing for a while, but the descent overheated the sidewall and boom.

post up pics of the tire.

Chandne

I'll definitely post pictures. So it was about 50 degrees and I had just started my descent. Rear PSI was about 100. It was actually the first time I braked on that descent so if it had overheated, it was brake run, not me braking. So that is a good point- the brakes rubbing. The brake was definitely over to that side but I figured it was due to the crash. I'm curious to see what you guys think after seeing the tire. I have 2-3 pics on my phone. I can take more.

Chandne

Chandne

The white-looking sheet inside the tire is my energy gel pack holding in the tube.

Maelochs

I wonder if he had locked up the tire and was skidding on the sidewall---I have eaten 90 percent through a tire's tread---the thickest part-- in a severe lockup so it seems possible to me that a couple seconds sliding on the sidewall might have torn it enough for the 100-psi tube to squeeze through and any contact with pavement then ... would leave us where we are now.

I always like to hear a crash story that ends "... so I picked up my bike and rode on " ... Particularly when it starts "I was descending at insane speed .... "


So, thanks for surviving to entertain me.

Chandne

Well, I would not call it "insane speeds" but just a bit hotter than usual. Yeah, I'll certainly be slowing down and you are welcome.

EDIT- I added some pictures. I can take more, though I think these are pretty clear.

Jiggle

Yep, that'll do it. iirc the sidewall thickness is less than 1mm. You can carry a needle and thread in your gear in the future to sew these up and get you home.

woodcraft

Maybe first went down, then wore through the sidewall...

Chandne

Good observation but it definitely went flat just before I was down. When I went down, the rear tire was practically off the asphalt.

nycphotography

Second picture, I see what looks like brake wear right above the rim on the right. Might be good to see the rest of that feature?

Yet the blowout definitely does not look like brake rub.

Fascinating.

Fiery

How far would you have to lean in order for the sidewall to actually contact the ground? Is it actually possible to lean that far without sliding out, even without locking up the wheel? I would think that you were already beyond the point of no return by the time the tyre ripped.

Lanterne Rogue

I wonder if your tire was over-inflated. If you set your tire pressure at, say, 5,300 feet in Denver, it would gain significant pressure as you doubled your elevation to the top of Vail Pass.

rm -rf

Down near the top of the rim? That looks like the usual tire casing wrap over the bead. Continentals can look kind of messy there, but it's normal. A frayed look or loose threads there are common.

Yeah, a very big lean over. I thought that about 45 degrees of lean was the limit for road bikes.

Perhaps a small rip at the top, then a quick deflate and wheel lockup did the rest? Still, kind of unusual.

Air pressure at 5000 feet is about 12 psi, and at 10,000 feet about 10 psi. Only 2 psi difference. Even sea level, 14.7 psi, to 50,000 feet is only 13 psi less.


~~~~~~~~~~~~~~~~~~

Braking for a sharp turn

I use just the front brake, slowing as much as possible before the turn. I've fishtailed when hitting both front and back brakes hard--the rear locks up and starts sliding around.

My plan is to let off the brakes completely in the turn, so all the tire friction force is available for turning the corner. But it's hard to actually let off the brakes, I really want to keep braking!

I'd like to avoid those situations, so I'm trying to slow down more than usual on unfamiliar roads.

~~~~~
Glad you could get home okay!

Gladius

I assume this is descending from the top towards Copper? Those are some twisty paths, and narrow in spots. On RtR and Copper Triangle they post a state patrol on a motorbike on a couple of the tightest turns in order to warn people to slow down.

Regardless, none of that explains the blowout. It definitely looks like a friction abrasion, now to figure out what caused it...

Gladius

Is it possible that you were *under*inflated, maybe due to a slow flat, and that the abrasion occurred as the sidewall collapsed and the tire skidded?

andr0id

Look at last photo an how much rubber is missing all around that hole. The tire is abraded all the way to the shark fins on the left and right.
I think your psychic forensic skills are spot on.

No, and and a brake rubbing a tire leaves a worn ring just above the rim all the way around the tire. That's not in the photo.

noodle soup

Sounds like the old Summit Stage.

mpath

Good work, MacGyver.

Chandne

I did not check the tire pressure on top of Vail Pass but I inflated in Breckenridge to 100 PSI. It felt fine. I'm used to leaning over pretty far but this corner caught me off guard so like my motorcycles days, I just stayed leaned over and should have counter-steered a bit like I have. It was my mistake to hit the brakes at all in this case. Now, it is entirely possible that I have a slow flat and I would not notice for a while.

Yes, this was descending from vail Pass to Copper, but pretty close to the top where there are 3-4 really tight turns. It opens up right after that. It was the left turn right before the bridge.

The casing looks like that because in that pic, the tire is pretty much deflated and folded over a bit. I just looked and it is perfect. Well, except of that massive hole.

I think I have been getting too bold over this past year and really leaning over too much, enjoying tiefeeling I used to get on my motorcycles and on the occasional track day. I think the sudden nature of that corner just overwhelmed my skills. If I had not braked, I probably would have made it through just fine. Honestly, this was a good lesson and I will be much more cautious around corners.