87

I happened to do just that. I took an old hand pump and an inner tube to the bath tub. Submerged the pump and pre-filled the tube with water, complete with burping out any air bubbles. With the tube moderately full and free from air, I put it on the rim with the tire. Then the final pressure up. The first thing to notice is that the pump operates with ...


32

TLDR answer: you ran over something Given the ding/cut in the rim itself that aligns with the cut in the tire, you ran over something metal that was sharp enough to cut your tire and even dig into your rim a bit. That looks like a deep carbon fiber rim - if so, I'd recommend doing a better job watching what you're riding over because the next bit of debris ...


31

Most likely this low number refers to inflating the tubes without the tire, as a balloon. When installed inside a tire, the majority of air pressure is held by the tire casing, not by the tube. A similar warning about not inflating outside of/without a tire came with my Tubolito inner tubes, but the wording was more clear in my case.


22

It is talc, and it is used in the tube making process to prevent the inner tube rubber from sticking to itself.


22

I've seen that color before. If you are filling from a compressed air tank, make sure the tank has been bled recently. More frequently in humid areas air tanks will get condensation inside. Normal maintenance is to bled the water out of the tank. The condensation rusts the inside of the tank and can eventually cause tank failure. When you put an air line on ...


22

Do whatever works, really. The problem with the container of water approach is that it requires a container of water. It won't damage the tube. Also, if you need to patch the tube, you have to wait for the wet tube to dry. So, I'd generally recommend doing this last (usually leaks are not subtle enough to need the immersion), but no harm going there first. ...


22

Definitely a cut - the damage to the rim and the fact that the rubber and carcass fibers are clean cut through confirm that. If the tire burst from over pressure you'd see ragged edges. Also, from what I remember of mechanical engineering classes in college tubular shapes split along their axis when over pressured, not across. My first thought when looking ...


21

There is a mark in the middle of the valve stem as if something has pressed against it: Given that it was a fresh new tube, it likely means that it had been installed with the valve protruding at a sharp angle from the rim hole. Externally, it will look like this: This is bad because the air pressure creates additional uneven stress to the rubber around ...


21

Check that the rim tape (tape or liner that sits in rim bed) is not loose or spinning. I had an identical issue where a brand new tube would be ruined after a 10 minute ride. The rim tape spins on braking and drags the tube with it effectively tearing the tube away from the valve. If this the culprit, throw the current rim tape away, it can’t be fixed. ...


21

Yes, some people still patch their tubes I've worked sales at a bike shop for three years, and patch kits are still one of the most common small items for us to sell. It still makes sense from an money perspective--a patch kit is $2 and can fix 10 tubes, while tubes are $10 dollars each (for good ones, at least).


19

The usual causes for this: Presta valve in Schraeder hole without proper reinforcing grommet. Valve crooked, or being forced crooked at the expense of extra stress on the tube/valve joint by riding with pressure too low. Burrs around valve hole. Knock down and replace with a neat bevel with swivel deburrer, tapered reamer, small round/needle/rifler file, ...


19

Yes, you will need a rim tape to protect your inner tube from the spoke holes or the spokes in your rim. There are a few exceptions we come to later. The rim is the outer part of your wheel. Along its or circumference run two flanges to hold the tyre in place. Between the flanges is the rim bed. A rim tape usually needs to be in this bed. Thus can be a ...


18

I've glued hundreds of tubulars and learned the craft from some of the best mechanics in the sport including a former wrench with the Motorola team and a former Mavic Service Course mechanic. These days tubulars are really only used in cyclocross, track and at the very top level of the sport. There are some very distinct downsides: Safety. Improperly ...


18

It can't burst the tube, because the tube is completely surrounded by the tyre and rim. Bear in mind, though, that higher pressures don't automatically mean a faster ride. There are two competing factors: a soft tyre is constantly losing energy due to being squashed flat against the road, but a hard tyre loses energy because any bumps you go over have to ...


18

I think its worse than that - your valve core is not there, but the thinner thread where you connect the airhose is there. That tells me the shaft of the valve core broke off, the acorn nut was lost, and the guts of it fell into your tube. This is what a removable valve core looks like: Your tube appears to be like the one on the right, with no removable ...


17

To follow up on what Batman says, what you use to find the leak depends a lot on the circumstances. If you get a flat by the side of the road (and you don't have a spare tube) then you obviously can't use the tub of water (unless you find a convenient pothole filled with rainwater). In other circumstances the water tub (or bathroom sink or whatever) is ...


16

This kind of failure is basically the reason sticker-type patches have a reputation for not being reliable. Scrupulously sanding the area and getting it as clean as possible (ie, with alcohol or other residue-free solvent, cleaner than anyone can probably get it on the side of the road) wards off the problem but doesn't eliminate it. Sticker type patches ...


16

It is common to inflate a tube just a little bit before you install it in the tyre. This gives it some shape and helps prevent it getting twisted or pinched, with a little care from the user. This is the stage described in the manual you've shown. With a standard butyl tube you can inflate those much more than needed with no ill effect, the rubber just ...


15

As a heavy rider personally, I don't have many issues with flats. A normal tire on the high/maximum pressure works fine to avoid pinch flats. The key is to check tire pressure every time you get on the bike. Even a day will allow a tire to soften 10 psi, and that will allow flats to occur. Road hazard flats are not avoidable except by avoiding the ...


15

You have to remove the wheel to replace the tube. A repair can be done in the frame. On older bikes without quick release, and with current gear hubs, electric hubs, Nuvinci hubs, belts etc, you need a spanner and oftentimes, the gear adjustment goes back different and needs fiddling with. This reduces the advantage of tube changes. A fix is only 3 mins. ...


14

This kind of failure is typically caused by excessive wear on the brake surface of the rim. Every time you apply your brakes, you are polishing small amounts of metal away from the rim. Eventually, the rim gets too thin and weak, and will crack, like you have seen in your photo, from the normal inflation pressure of the tire. In general, this means tht ...


14

It should be straight out, perpendicular to the rim. Otherwise you risk damaging the tube. When the valve stem is at an angle the valve isn't free in the hole – it is trapped by the edges of the hole where they bind the stem. The edges of the hole may cut the stem which will be moving a little bit as the tire and tube flex over bumps and the like. There ...


14

Yes - absolutely, though not on the roadside. Here's a spare tube out of what was my main commuter. I counted and it has 15 patches applied, though some of them are snake bites and get two. Presuming a patch costs $1, and a new tube costs $5, then this tube represents $50-$70 in savings of not buying new tubes, and there are not 10-14 other tubes lying in ...


13

The tire sidewall is just hung up on the rim a little. It’s a common problem. Deflate the tire until you can deform it a little with your hands, rotate the wheel so the problematic section is at the top. Grab the tire from the side and lever it back and forth. You should be able to pop it out so the bead sits on the rim properly. BTW, a pressure gauge is ...


13

I believe pre-glued patches were always intended to be a temporary fix to get you home. When they first came out on the market I remember explicit warnings that these were not a permanent fix. Waiting for glue to set up on the side of the road is a pain, and these were intended to solve that issue by providing a quick fix to get you moving again. ...


13

The culprit is the rim tape. The glue that holds it in place has lost its grip, and when the tube is inflated, the tape is pushed away and lets the tube to extend into spoke hole. Eventually the edge of the spoke hole cuts the tube with the results that you described. In my experience, this is what cloth rim tapes do. They can be replaced and there are ...


13

You seem to be missing the valve core in your Presta valve. Perhaps you removed it? It is the most important part, it must remain in the valve. If you no longer have it, you need a new one or a new tube. We have many questions and answers about using the valve here. You just unscrew the small safety bit on the pin, optionally screw on an adaptor and then you ...


12

My rule of thumb is the following: Never patch a patch: when a puncture is too close to another patch so that the patches would overlap or almost, then I toss the tube Never patch too close to the valve: the valve makes is a structural anomaly in the butyl that makes the tube, so is a more sensitive area, not to mention all the air input comes from there so ...


12

What kind of valve do you have? If you have Presta valves then you need to unscrew that little knobbie thing on top until the knobbie is all the way unscrewed against the bump on the end of the shaft it rides on. With either Presta or Schrader you can have a problem with the pump if you do not press the pump chuck all the way onto the valve. Especially ...


12

Yes, inner tubes do that. They are like balloons, except that the butyl rubber they are made of doesn't stretch like natural latex rubber. You are not supposed to inflate tubes outside a tire. Tires have fabric casing to withstand the pressure.


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