Earlier today I was in the bathroom an heard what I thought was a gunshot outside, VERY close to my front door! I was pretty startled and slowly opened the door to peer outside. No sign of anything unusual. I walked around the house and looked all around and still nothing unusual, and I forgot about it. Several hours had passed and I went to change the cranks on my 29er, and that BANG I had heard earlier was actually the TUBE blowing the tire off the rim! Just glad that didn’t happen while I was riding it!
Fast forward to my LBS.
Turns out that this particular tire was just a very poor fit; It was going on the rim way too easy, without the need of tire levers. The tube wasn’t defective. It simply blew the tire off the rim, which also caused the tube to fail. This was the exact same issue we had when trying to find a lightweight 24" tire for my Fargo climb last year. We tried a couple different bmx tires, and I even made videos of my practice climbs, where you see the tire blow off the rim! This happened three times until we found the perfect tire!
So at my LBS earlier tonight, when we were installing a new tube, we were having trouble getting the bead even, (bad sign) then pumped it up little by little, until we got it to 50 psi, which is 15 under max. All seemed ok, but then we noticed the bead had partially come OUT on one side! We let the air out and tried to re-seat the tire, thought we had it, but after getting it to 50 psi again, I noticed the bead was creeping out - again! We threw in the towel at that point.
So I need to find a tire that fits properly and snugly. I do have two ardent 29er tires, but I want a lighter tire with less aggressive tread, for road climbing. I’ve got this one on order, arriving Tuesday. If it fits tight on the rim, it should be ok.
When I bought my first 28", the tube was inserted badly - I assume with a Z fold. I pumped it up to about 60 psi and I was tonking along an unmade road when suddelnly there was an almighty bang as the tube exploded. The uni stopped and I carried on. At the time, it felt like I’d hit the ground running several yards from the uni.
Years before that, well intentioned friend pumped up my 20" tyre using a track pump. He then left the uni parked in the sun, leaning against a white painted garage door. The heat took the pressure up a bit higher and the bang was pretty spectacular!
I had a bike tire blow out in my cubicle at work one day - usually I rode the beat up fixed gear bike, and would leave it outside, but I’d ridden the nice bike and wanted it safe - there had to be 100 people in close earshot when it went BANG!
Also had one blow in my car when I was driving home from a race. That was kind of exciting.
I think both times it was due to a combination of poor mounting and then a temperature rise, cold outside, 40+ degrees warmer when they blew.
Traditional road tires are typically much too narrow to be compatible with the kh rim, which is 47mm wide. Some have opined that the 29 x 2.1 tire that just blew off, was probably too narrow for the kh rim. I’ve run 2.0’s before without issue, so I’m not sure the 2.1 width was to blame.
The KH rims are super wide by road bike standards, and also much more or a square profile. They are ideally made for wider, heavier MUni-type tires with a wire bead. The narrowest folding tire I’m running with 100% success is the 26 x 2.25 Ardent on my G26er. It is a mountain bike tire with profile that is perfectly compatible with the kh rim.
I do think that if the tire fits on the rim much too easily, a blow off is more likely. My blowout reminds me of bad situation a few years ago, where there was a bad batch of 36er TA tires that were made just a tad too large, and several people complained of tires blowing off the rim, some while riding! One option for running a narrow, tubeless road-only tire would be to simply build a new wheel with a proper road rim. Only problem there is, most road bikes are 26ers, not 29ers. Here’s one.
Only problem with a narrow rim is that my magura rim brake pads will not be able to reach it, because the KH frames are made for the wider rims. I might be able to get away with the KH “XC” 29er rim, which is 38mm, or 9mm narrower than the drilled rim.
Something like This might make a great road climbing tire with the right 700c rim, built with my nimbus hub. Wire bead, 32mm wide, and only 400g. Just hope the hub’s width would be compatible with the much narrower rim.