Really? Double pinch flat at 30mph

pdmtong · #1 10-07-2015, 07:15 PM

Conti 4000s at 105psi on mavic kysrium SL (2010) // 170# rider

Everything was going great. Descending the straight 1500m section I've ridden hundreds of times (Portola east just west of whisky hill just west of stanford) when I feel a thud as I hit a pavement discontinuity in the bike lane. Damn spackled light. No time to lift the front or hop.

The thud is followed by a whoosh as the air immediately leaves my tire and now I feel that thud thud thud as the tire comes around and I am hitting the valve stem bottom on the rim. Except whats different here is I feel it in the front AND the rear.

Are you kidding me? Oh, and I am going 30mph. I guess the 45,000 feet of DH at lift-assisted Northstar-at-Tahoe my daughter an dI did the past month helped to stave off panic as I tried to slow the bike down in a straight lone and not roll a tire off.

Managed to stay upright. Made the cell phone call for pickup.

Each tube has a 4mm knife slit parallel to the seam on the rim side where the tube just opened up. No gashes or cuts or holes in the tire in that location.

I have never had this happen in my life on the road. MTB once.

Anyone else experience this catastrophe? Maybe its a signal to switch to tubulars? I guess one is an accident but both has to be just bad luck.
Went back and looked at the offending pavement - yup, its there. A lip that shouldn't be a problem evidently is a problem when the speed increases.

Black Dog · #2 10-07-2015, 07:24 PM

Speed multiplies force. You should try latex tubes. Much better in a situation like that.

unterhausen · #3 10-07-2015, 07:42 PM

I had it happen, fortunately it was at the bottom of a hill, but I was going fast. I went back to look to see what it was and couldn't find anything. I have been through that section of road many times. I also had a double pinch flat in the dark, but there was a giant pothole involved that time. That was annoying, 10 miles into a 300km ride.

moose8 · #4 10-07-2015, 08:09 PM

I'm glad you came out of it ok - I have yet to have a double flat like that and really hope I never do but I imagine it's pretty scary (I have had horrible luck with lots of flats on a ride, but not for a long time since I paid more attention to the wear on my tires).

Louis · #5 10-07-2015, 08:17 PM

Are you sure you were up to 105 psi or had it been a while since you checked the pressure?

ultraman6970 · #6 10-07-2015, 08:19 PM

Go and play lotto, might be your lucky day.

beeatnik · #7 10-07-2015, 08:54 PM

Glad you kept the rubber side down, P.

Um, don't think I've ever pinched both tires simultaneously. But I have had multiple rear pinch flats in one ride. Both flats were a function of speed (25-30mph) and wheel type. I had pretty bad luck with Shimano C50s.

dpk501 · #8 10-07-2015, 09:56 PM

way to keep the rubber side down. glad you're ok!

echappist · #9 10-07-2015, 09:56 PM

at least three occasions. Once descending on a twisty road at 30 mph when i just started riding. Very lucky i didn't crash.

Then a few months ago while on my TT bike. I still don't know what I hit, but as i was on my extensions, there was no chance to do any correction and had my worst crash in five years. The cut was so severe that there were snake bite marks in the tire carcass as well...

i definitely trust tubulars to be safer in this aspect.

mgm777 · #10 10-07-2015, 10:19 PM

Hey, you were able to walk away with all your skin intact. I call that a win. Chalk it up to bad luck and continue on. Probably won't happen again, hopefully, for a long, long time. Sometimes, stuff just happens.

Dr Luxurious · #11 10-07-2015, 10:43 PM

Yes, it happens.

Happened to me here at about 35MPH

https://goo.gl/maps/BdBTDSMsNiM2

Hit something and the front went instantly flat. The back blew about 1 second later.

Tony · #12 10-07-2015, 11:04 PM

Quote:

Originally Posted by Louis

Are you sure you were up to 105 psi or had it been a while since you checked the pressure?

This.

105 psi, 170 lbs rider, double pinch flat, only a thud.
Glad you made it out OK!

pdmtong · #13 10-08-2015, 12:15 AM

Quote:

Originally Posted by Tony

This.

105 psi, 170 lbs rider, double pinch flat, only a thud.
Glad you made it out OK!

Yes 105psi. I just swapped the tires that morning

Like all near accidents - that could have been really bad.

I was on my ciavete respo. Would have really sucked to have helicoptered that frame

A general crash rule. It's either really bad for the rider or the bike but seldom both

beeatnik · #14 10-08-2015, 04:06 AM

pdmtong, you jinxed me. earlier tonite, riding south on Beachwood Drive (the street one takes to get to views of the Hollywood sign) I heard my pal's bike explode. Looked back and expected to see him on the ground. Fortunately (or unfortunately) he had only collided with a bad patch of raised pavement and double pinched. Exact...same...deal...as....you. Best of all the dude didn't have any tubes on him. By chance, earlier in the day I picked up Park Pre-glued Super Patches. We were able to save one tube (the other had double snake eyez or 4 cuts).

etu · #15 10-08-2015, 07:21 AM

Had a double pinch flat when I was visiting Boston and on my way to Ti Designs. It was a rainy morning and I was riding tires that were probably a bit underinflated since I used my hand pump. I didn't notice a water covered small pot hole on the bike trail and went straight into it. Bam, bam! Double pinch flat. The worse part of it was that like most I carry one tube and a patch kit, and trying to patch a tube in the rain, especially a 1cm gash, doesn't work so well. Luckily a generous commuter help me out with a second tube.