Flat tire troubles

I have been commuting to work on my KH29 (4.6 miles each way) anyway, the other day in my office the tube just popped very loudly. I then went to the bike shop and picked up a replacement. While filling it - up to about 50lbs, it blew out as well. Today I took the wheel to the shop - they inspected the rim and tire - he thought that the tire (Schwalbe Big Apple 2.0) was loose on the rim (from the blowouts?) and that it might be the problem. He then put a new tube in and I left to put the unicycle back together for Mondays ride. I just joked with my wife that I better go check to see if it is ok - and guess what - it is totally blown out. What gives? I replaced the rim strip with a much better quality cloth rim tape as well - does anyone have any advice to offer?

Thanks Bo

Is there anything that ties together all the flats? When you say “blowout,” I assume it’s a big hole in the tube–is that so? If so, does the tear show up in the same spot on each blown tube? It could be a weak spot in the tire, I suppose, if there’s some consistency to the failures.

I haven’t had anything similar, although I did have a pretty catastrophic blowout when commuting on my KH29 a couple years ago–but I think it was an extreme snakebite, as I had bumped through a pothole when it happened. It sounded like a gunshot, and tossed unceremoniously off the uni. And at that point, I had only had the uni for maybe a couple weeks. The original tube was not particularly good, but the replacement has lasted me probably 1500 miles since.

It sounds like you are blowing the tire off the rim. The problem is that once a tire blows off a rim it can wear that section of the tire where the bead seats in the rim. It will cause the tire to blow off consistantly in the same spot. Sometimes the wear is obvious, and other times the wear is barley noticeable, but still results in the same blowout. If the tire is new and you don’t want to replace it you may try gluing it on the next time you mount it. It would be better if you knew the section that was blowing off, and just apply the cement to that section of the bead. I would use sew-up glue like tubasti. It’s my favorite because it doesn’t dry out like some of the other’s.

One thing I noticed about my Big Apple is that it is a loose fit on my KH 29" rim. I have to inflate it partially and take my time seating the bead. At least once I saw my bead pop off the rim while I was inflating, and I immediately deflated it, and seated the tire manually.

One last point, although this is unlikely because a bike shop installed it, is that you need to make sure that you don’t pinch the tube with the tire as you mount it. If there is a little bit of tube between the tire and the rim it will blow your tire off the rim.

I feel like I am rambling on a bit. I hope this helps, but if not I’m sure there will be more help on the way.


Yes, sounds like you may need a new tire. I’ve experienced that a couple of times over the years, where a massive blowout has damaged the bead so the tire will no longer fit. Sometimes it’s more obvious than other times.


Thanks guys - I will order a new tire, does a Schwalbe Marathon fit on the rim better than a Big Apple? I want to avoid this forever - and just ride without worry.

Thanks again for the replies - I really appreciate it.

What size tube is it?

Is it a 29" tube, or a 700c touring tube?

I’ve had this happen with touring bike tubes (usually rated up to 40mm tyres, they tend to pop in 50mm tyres), and bike shops will often fit them as they don’t have proper 29er sized tubes.


I have only ever had one tyre come off of the rim, which also happened to be a 2" Big Apple. It didn’t pop the tube though! It was on a particularly rough bit of road in the centre of London with pot holes and deep trench like grooves from the busses, so I blamed the road surface. I’ve probably done as many miles on the Marathon Plus tyre as on the Big Apple, and never had a problem with that.

STM - a big fan of the Marathon Plus tyre anyway.

it was a 29" ATB tube - I am going for the Marathon I think. I wish that there was a 29" Hookworm out there.


I like the look of the Kenda Small Block Eight

If the tyre and tube are OK (undamaged and correct size), make sure you’re not pinching the tube when fitting the tyre. It’s quite easy to get the tube trapped between the tyre bead and the rim, and they can often survive some time in this state before suddenly blowing out for no apparent reason. When you fit the tyre, make sure you check all the way round the bead to make sure the tube isn’t trapped (putting a tiny bit of air in the tube while fitting helps). Sorry if you’re a seasoned tyre fitter and you already know all this of course!


It’s not a hookworm, but I saw a Serfas Drifter City 29x2 at my LBS, and it looks like it might be a good uni tire. It has a round profile, and sturdy sidewalls. It’s also rated to 65psi.

That looks like it might be pretty good for fire roads and mild muni, but I think it would suck as a road tyre though.


Schwalbe is going to send me a replacement tire (2.35 Big Apple) - There are some nice people at that company, you can feel confident that they stand behind their tires. He even said that he will send a tube. He said that the 2.0 is way too small for the KH rim and that the bead is barely hanging on - use caution if you are using this combination.