85

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 ...


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. ...


20

It's not unusual for narrower tires to need pumping up every day or two, but if they really are losing air after "a few minutes" then the tubes have been holed somehow. Did anyone check the tires for small pieces of wire, etc, sticking in them? A tiny piece of wire can puncture a new tube within minutes. Did anyone check the rims to make sure that the ...


19

Note: this calculation makes many assumptions, so it's only useful in an 'average use case', not some sort of exact measurement. If you find better information, please post it and I'll update the answer. How many pumps you would need to fill up a tire depends on many variables. First, the volume of your inner tube, which can be approximated as a torus (...


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

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 ...


17

From personal experience, I'd say a larger-than-usual hole in the tire could have these undesireable side-effects: The tube might get a bit exposed, and the day-to-day rolling over the hole might wear it down until the tire eventually flats out. Chemical aggresion from road grime or mud could also be involved. The fabric of the tire might get damaged to the ...


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

Sometimes it can be hard to find a small hole. Sometimes it helps to mix water and dish soap together and either pour that over the partially inflated tire, scanning for leaks or submerging the tire in a bucket of soapy water. The soap will bubble and make holes more apparent. You also probably want to immerse the valve to see if the leak may be ...


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 ...


15

Generally, if you are using an inner tube in the tire, you should replace the tire if there is more than a 2 millimeter cut in the tire casing. Not in the rubber, mind, but it the threaded cloth casing that your rubber bits are laid on to. I personally err on the side of replacement rather than risking a serious injury from a blow out at a bad time, so I ...


15

The inner tube has no significant effect on max pressure. The valve stem area is the only area sensitive to pressure, and in general the valve can withstand 200 PSI or better. (And if you exceed whatever limit there is the result is "catastrophic" failure, not simply the inability to pump in more air.) What it sounds like you're noticing is the geometry ...


15

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 ...


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

Schrader valve/Schrader tube aka "American valve" or "Automotive valve" The Schrader valve consists of a valve stem into which a valve core is threaded, and is used on virtually all automobile tires and most wider rimmed bicycle tires. The valve core is a poppet valve assisted by a spring.


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 ...


13

The size of the tube is usually written on the box. Tubes stretch a bit so they fit a variety of sizes. For a 27 x 1 1/4 tire you would need one that says 700x32 which is the equivalent new size of tube, although both the old system and new system are usually written on the packaging. This size is very common and you should be able to purchase the tube at ...


13

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 ...


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

That's called rim tape and it protects the tube from sharp edges in the rim and the ends of the spokes and spoke nipples. Without it you will get endless punctures. Most wheels come with rim tape installed, but you can buy it separately. It's not hard to install, you just have to make sure you get the right width for your rims: wide enough to cover the ...


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 ...


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.


11

Generally, you repair tubes, not tires. From your last sentence, it sounds like you are indeed talking about the tire. As it is with the tube, the real answer is "Size Matters". In this case, both the size of the hole and the size (okay, type) of the tire. If I was looking at damage to a road tire "slick", the hole you describe would likely having me change ...


11

According to Yehuda Moon (google it), you can take a properly-sized ball bearing (or even a pebble) and put it inside the valve cap, then screw the cap halfway so that the ball/pebble will keep the valve open. Then, you roll the tube like toothpaste, and when you finish you remove the cap and the pebble to avoid the natural elasticity of the tube to suck ...


11

It's not going to be directly proportional. Leaving aside the quality of the tyre and what it will be rated for, the shape of the graph is likely to be a U shape: at the lower pressures the tube will be susceptible to puncture because it cannot repel sharps adequately, in addition really low pressures might let you trap the tube between the road and the rim....


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