32 votes
Accepted

Why does the manual for the inner tube say the maximum pressure is 4.5 PSI?

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 ...
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32 votes
Accepted

Tyre exploded while riding

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 ...
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  • 8,783
25 votes

What powder is used inside an inner tube?

It is talc, and it is used in the tube making process to prevent the inner tube rubber from sticking to itself.
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  • 45.5k
22 votes

Why does my inner tube have brown liquid inside? Now with internal photo

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 ...
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22 votes
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How to find punctures in inner tubes?

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 ...
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  • 45.5k
22 votes

Tyre exploded while riding

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 ...
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21 votes

Unable to get a tube replacement to last

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 ...
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21 votes

Unable to get a tube replacement to last

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 ...
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21 votes

Does anyone patch inner tubes anymore?

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 ...
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19 votes

Presta Valve Keeps Ripping From Tube

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 ...
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19 votes
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New wheel. Does it need that little rubber lining between it and the tube?

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 ...
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  • 8,962
18 votes
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Tubular Glue vs Tubular Tape

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 ...
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  • 1,594
18 votes

Can I pump my MTB tire to max (55 psi / 380 kPa) without the tube inside bursting?

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 ...
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18 votes
Accepted

Unable to pump air in my bicycle tube

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, ...
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  • 99.3k
17 votes

How to find punctures in inner tubes?

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'...
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17 votes

How can I patch a hole on the underside of an inner tube?

It does not matter on which side the hole is, the process is exactly the same anywhere on the tube. Be sure to let the glue become more viscous and sticky by waiting for a while before applying the ...
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16 votes
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Technique for self-adhesive puncture repair patches

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 ...
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16 votes

Why does the manual for the inner tube say the maximum pressure is 4.5 PSI?

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 ...
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  • 12k
15 votes

Heavy Rider (300lb+) - Please recommend a 26" tyre to avoid tyre pinch

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 ...
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  • 29.3k
15 votes
Accepted

Why using a puncture repair kit instead of a new inner tube?

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 ...
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  • 1,028
14 votes
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Does the valve have to be straight when replacing a tube?

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 ...
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  • 6,886
14 votes

Does anyone patch inner tubes anymore?

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 ...
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  • 99.3k
13 votes
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New high quality tire doesn't sit evenly on the rim

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 ...
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13 votes

Technique for self-adhesive puncture repair patches

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. ...
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  • 29.8k
13 votes
Accepted

How did these pimple/bubble/bump shapes form on my tube?

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 ...
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  • 19.4k
13 votes

Unable to pump air in my bicycle tube

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 ...
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12 votes

What do I do if my bike won't pump with an air pump at all?

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 ...
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12 votes
Accepted

Is it normal for an Inner tube to bulge when inflated?

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 ...
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  • 19.4k
12 votes
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New inner tube bulges near the valve when inflated

Unless the tire bead (the re-enforcing wire around the edges) is damaged your tire is simply not seated on the rim properly near the valve and has popped off as the tube was inflated. Tube size seems ...
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12 votes
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Tube patches: dedicated ones or recycling old tubes?

Recycling tubes as patches works, but its a lot more work and can be error prone. You cut an oversized piece of tube and dust off all the talc. Then stick a loop of tape on the back side as a ...
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  • 99.3k

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