defective tubes?

I recently purchased 5 20x2.125 tubes. Now I have had tons of experience with these…never really any blowouts, even on huge hops and drops…pinch flats used to be rare, but more frequent as I ride more now…but still no blowouts… I also use 45-50 psi , which is what the tire calls for…well…35-50. anything lower than that, and the rim bottoms out too much as i weigh 170.

anyways, tonight, after 4 days with no unicycling because I had no tubes…I
received my 5 tubes.

1st tube: I aired it up to about 45 or so psi and hopped up once. Decided it was too low. aired it up again to 49 psi…and rode to the end of the driveway. I suddenly fell forward, thinking i hit a pinecone i didnt see. as i was angrily falling forward thinking about how i was going to kick the pinecone out of my way, boom. the tube exploded.

2nd tube: More cautious now as my ears are ringing and im a bit startled…aired slowly…slowly by about 3 psi each time, checking it with the pressure guage to make sure its not going too high. BOOM, exploded right in my face.last psi I measured was 45. luckily I had put on my headphones because I was afraid of an explosion.

3rd tube: once again ears ringing…VERY cautiously airing it up this time…with TWO pressure guages being used to check, and on a different 20" nimbus.(both have cc though). I decided I was only going to try 40 psi this time. I got it to 40, rode literally 10 feet …fell forward…BOOM. only a measly 40 psi.

I think im going to email and see if they will replace my tubes.
this is 21$ instantly burned. for nothing.

i am also now too afraid to try my last 2 new tubes. ill be putting in ear plugs and wearing glasses and gloves when I do. hell, ill just put on all my unicycling armor and do it.

has this happened to anyone else? will udc replace my tubes?

what kind of riding do you do? 40 seams a bit high. i think i ride down about 30

I do trials. I used to ride at 35, but as my legs got stronger and I started doing higher stuff ive had to increase the psi gradually because of the rim bottoming out. 35 is now incredibly low…

did you check the rim for anything that could damage the tire? spokes?

Wild story. I’ve never had such a thing happen to me, even though I buy cheap tubes from Wal-Mart and such. Could very well be a defective batch of tubes, unless you have a piece of glass or something in your tires. Even then, I wouldn’t expect it to explode.

I like my tire pressure high, like 60psi. Maybe that’s because my tire is not as high volume as the ones you guys use…

i checked both tires and both rims for thorns/glass etc…lifted the rim strip to see if there was any spokes sticking out…none. its really weird.

A batch of faulty tubes is possible, but first everyone is going to want to know if there was any “rider error.” Sound like you’ve covered the search for sharp edges inside the rim and tire. Is it possible you did something destructive when putting the tire onto the rim? Any metal tools involved? Anything else you can think of that may have killed a non-defective tube? If you can’t think of anything, it could be the tubes. Report all of the above to and see if they’ve had any other problems with those tubes. If it’s the tubes I’m sure they will replace them for you.

A single blowout can render a tire useless. I have seen many tires that looked almost perfect that wouldn’t stay on a rim after a blowout.

I would try to install another tube and slowly inflate it. Bring it up to maybe 10psi, and look all the way around on both sides to see if there is any sign that the tire isn’t seating.
If all look good then give it a little more pressure, and look at the mount again. if you hear it moving around as you inflate it that is usually the tire seating, but in your case it might be the tire blowing off the rim. You should have a valve tool handy just in case you need to get the air out of the tire fast.

If you are blowing out your tubes it is unlikely that it is the tubes unless they aren’t in the tire. The tire holds the pressure, not the tube. Blowouts happen because all of the pressure finds a weakness in the container (tire/rim) and goes there. If that small part of the tube suddenly has to accomodate a huge volume of air it will blow. The only times I have seen tubes blowout without destroying the tire, or blowing it off the rim was when the metal part of the valve was poorly vulcanized to the rubber part and the tube blew out at the valve.

Is your tire blowing off the rim? If so, it is probably happening in the same spot each time. After having worked on hundreds of flat tires, and blowouts I would say that you probably have a bad tire. Somewhere on the bead of the tire it no longer wants to hold the rim under pressure. If you look at the bead of the tire you can sometimes see a worn spot, or a place where the wire is bent. Unfortunately, it isn’t always very easy to spot. If you can find out where it is blowing off you can sometimes get away with applying a small bit of rim cement to the tire in that location.

In general the best solution will be a new tire.

yeah the the tire on the 1st nimbus was braaaaand new though :frowning:

its really ridiculous and annoying. I bought 3 nimbus trials unis so i would never be out of a 20 inch. now I have 3 disassembled nimbuses laying around with tires removed and no tubes. well 2 tubes but im afraid to use them now.

whats funny is when I got the tubes today and put the first one on…i was like watch this fail in 2 minutes…and sure enough it did.

Did you buy regular 20 inch tubes? Many of them cannot accomodate the width of a trials tire and will explode if stretched that far.

Regular 20x1.75-2.125" tubes are the only tubes ive ever used in my trials.

Jtrops is right about possible tire (bead) damage. It’s happened to me. Was the same tire used for all blowouts? One blowout can screw up the bead so the tire doesn’t fit tight anymore…

Go to a bike dealership. Motorcycle. Get a 15inx whatever. I’m ridding 14 or 15x 3.5-4 or something crazy. I hit rim a good bit, never broken one yet. Ridden the tube for trials for like two years. I’m a super noob, so that is amazing.


what psi are you able to safely use?

I think they were indeed defective. I got a extra thick tube that was 1.75 inch width, which is way too small for that tire and i have it up to 47 psi right now, and its holding, which is a much better start than yesterday.

so i’m going to go out now and do some hopping and ill see what happens…

also this new tube is on the tire that had 2 blowouts.

oh and upon closer inspection…the 3 tubes all blew up in the same exact spot.

im going to try my last 2 possibly defective tubes just for the hell of it…might as well try.

I don’t have a gauge, but pretty damn low. I hit rim a good bit, being a noob and all. Never had a problem yet, I’m guessing being a large fellow at 6,1 190 I run something like 35-45. I like my tire pretty stiff, I’m not so smooth on the landings which is why I hit. I’ve also hit rim jumping on trail tracks/rails/skinnies a fait bit and still no problem.

I was thinking of getting a regular tube since I’m kind of a weight weenie, but hell it’s just a pain in the ass. I’m a weenie, but not so far as to ruin my ride.

I broke something like 5 tubes in 2 days like 2 years back, got the moto tube and it’s been fine since.

yep, has to be the tubes. the 1.75 tube held up at 47 psi doing about 100 hops up 5 pallets and skinny riding etc.

so for the moto tube do you have to like stretch it out over the rim?

and how thick is the moto tube?

I just had the exact same thing - with a Schwalbe Big Apple (60psi) - I went through three tubes, luckily Schwalbe has a great warranty. They sent me a new tire and Schwalbe brand tube (looks to be great quality) and so far everything is great. It is a real pain, but maybe the tire thing is true - it may ruin them after a single blowout.

Not at all, I have to stuff it into the tire actually. I’m pretty sure it’s 14-15in, you can always take your uni in with you if your worried about sizing.

I’m not sure, but thick as hell, it’s quite over kill for a unicycle, but they last forever. Put them in and be done with it, period. In the off chance you do break one, I’m sure you could patch it and it would last much longer. Unlike bike tubes moto tubes are stronger, and meant for higher pressures so when they tear it will probably be small, if you do get one at all, they are definitely not going to explode, probably just kind of deflate.

I can’t recommend them enough, honestly. I like to get on my uni and ride, not fuss about with tubes what whatnot. Nothing like just getting into a good right and having your tire go flat in the middle of everything.

I had a blowout with my 36er yesterday with a 29er tube. Is my tire done for? I’m using a TA. It’s super thick so I think it’ll be fine. I was just about to convert it to being tubeless so I need to know that the tire will be ok.