I took the dog out on a few miles of gravel road as a test of the gravel roadster setup. Getting this bike on the road has had some silly setbacks, including two broken rear spokes at the beginning of two separate rides. There are other silver spokes mixed in with the black, so I bought three spokes when the last one broke. That should ensure that no more break!
We had a great run, up some brief hills, and along orchards and blueberry farms, looking out over the valley to the West. The sun only cracked through the overcast a few times, but cold gray is weather I like. We rode out a couple miles, and I goofed around taking pictures of the bike. We turned around to head back, since I didn’t want to stay out too late, and you never know what might happen.
Such as the rear wheel making a weird noise and sliding around on a descent! When I stopped, I saw that the tire had unseated, and the tube, still inflated, had doubled in size, looped out like a giant intestine, and herniated itself. A loop was bound up in the stays, and two feet of it jabbed out in the air. The tire had rolled off the rim somehow, and wouldn’t go back on.
I can put it on, but it just falls off. No matter how I try to mount it, I can see an air gap between the rim and the tire. I think the wire bead may have broken. I shlepped the bike back about a mile; sometimes carrying it, sometimes rolling it, but it didn’t roll that well.
I had a good laugh at my own expense, and I was out having an adventure in the countryside, so it was fine.The dog was a little non-plussed, though.
I did find a half-mile stretch of unharvested rose hips. They’re already withered, but they might be a possible gleaning site next year.
That bike looks great…except when spilling its guts. I’ve never seen anything like that before!
I’ll be happy if I never see it again! I’m glad it didn’t happen to the front. I still need to engage in a little scientific experimentism to see what’s going on with the tire.
Your rig looks like what I built for commuting/rough stuff.
I fooled around with big tires and had similar outcomes with no real explanation from basic rim and tire dimensions. I look and feel things to get my confidence meter to start reading.
Some tires have a shaped bead wire that limits the angles at which it can effectively engage the rim bead (they do differ). Even the round wire ones can exhibit a similar effect by the way they are laid up in the tire carcass. It is like the letter “S” . The negative result I have seen is when the rim/tire combo needs too much of an arc, in too small of a radius to keep the bead engaged.
Sidewall materials can be too stiff to permit this tight bend to form and increasing tire inflation, which seems intuitively the thing to increase bead engagement, actually makes the convolution pull the lower loop of the “S” straighter-reducing the engagement, if not just letting it off the rim.
The other thing I’ve experienced, when the really fat tire stayed safely on the rim, was premature wear presumably caused by the tight turn of the tire’s carcass as it bends over the rim/bead engagement. It seems to concentrate flex and wear right there as the “balloon” profile is exaggerated.
I ate 40′ of unimproved USFS dirt coming off the continental divide in Mineral County, Colorado when one of my Specialized Hardpack 2.2 tires running on a a set of rolled down Bontrager Mavics opened up along the bead line with a similar result to yours. Those tires were new with only a few miles of riding on them prior to the trip.
Owwwww…
I’ve ridden Hardpacks! We used to go Hardpack in the front, and Farmer Johns in back.
I think I get what you’re saying – some rim and tire combos don’t hook up very well, and under-inflating is better than over, since the pressure is pulling the bead ‘up’ as well as pushing it ‘out’ against the bead seat.
Also, the fat roll of the wide tire can wear on the rim itself.
I will definitely keep an eye on my tires.
Dyslexic agnostic cyclist with insomnia lays awake at night wondering , Is there a Dog?Rim tire problems can sometimes be solved with baby powder , tube does not stick in tire ,tire bead seats better.Back in the day ,prior to” scabs” ,patch kits came with a bit of talc to stop patches sticking to tire. I even carry my spare in a Zip-lock baggie with baby powder.All tire beads are not equal
Check out Sheldon’s page on and scroll down to the chart titled “Which tire fits safely on which rim?”
Having said that, it definitely looks from another post that your bead is broken. Glad to hear that you didn’t get hurt- that could have been a lot worse (for instance, as you say, if it had been the front tire…)
That was supposed to say, Check out Sheldon’s page on Tire Sizing” with the last 2 words linked…
Sheldon’s site is the best! I once spent 20 minutes trying to mount a 3 speed tire on an old Schwinn. Soap, water, tire irons, blisters, cursing, and then I slowly realized I’d seen something on that Tire Size page of Sheldon’s… about… multiple 3-speed tire sizes? Yep. 590, 597 (schwinn), both labeled 26×1 3/8!
http://sheldonbrown.com/tire-sizing.html
oops…