Run of pinch flats and I don't know why

[steverob]

I'll admit that I'm fairly useless when it comes to fixing anything on my bike, but one thing I am normally able to do is change an inner tube, albeit slowly - although with the practice I've been getting recently, I feel like I'm getting quicker!

However, each of my last three changes have resulted in pinch flats, two of those happening within 100 yards of leaving the house after the previous tube change and I can't understand what I'm doing wrong. One pinch flat I can understand if I was a bit slapdash with the change, but three in a row is surely almost impossible, especially when I took my time on the last two, following the recommended things to do to the letter, and also double and triple-checked everything looked okay with the tyre before setting out, only for it to still go "bang fsssssh" within 20 seconds is just aggravating.

I know no-one here can tell me exactly what's wrong without looking at either my bike or my tube changing methods, but any suggestions you can think of as to uncommon reasons for this or things I might have missed would be a massive help.

Things (I think) I've already ruled out: checked numerous times for any debris left in tyre from original puncture and have found none (also, all punctures apart from that first one had those telltale pinch flat snakebite-like holes in inner tube); ensured I've pumped tyres up to decent pressure (~100psi); tried a different brand of tube (in case the ones I was using was from a bad batch or had been in my hanging around in my garage for too long).

Even more annoying is that I got so fed up with changing tubes and failing on Saturday that I decided to go out on my old spare bike instead and after 18 miles, THAT got a puncture (thorn) as well, so now I've got two bikes to try my luck on!

 

[vickster]

Damaged rim tape?

 

[Bazzer]

You say about doing the recommended things to do. Does this include a little air in the inner tube before reftting the tyre? Also how are you getting the tyre back on. Pressure from fingers and thumbs only or are you using tyre levers?

 

[mjr]

Damaged rim tape?

^^ This, especially if the punctures are on the inner face of the tube.

Check all around the tyre after it's on and make sure you can see the rim tape and the inner tube is not trapped between tyre and rim anywhere.

Getting a flat again within 20 seconds probably isn't a pinch flat unless you felt the wheel grounding as the tyre collapsed flat (which means the tyre structure has failed and must be replaced), unless you really jump up and down on the bike as you pedal. Are you really sure it's a pinch flat and not two sharps stuck in the tyre close together? Are you checking the inside of the tyre where the puncture was or just the outside? Can you try a spare tyre?

 

[fossyant]

Also talc the tube - makes life easier.

 

[Katherine]

Your tyres might be worn.

 

[steverob]

Damaged rim tape?

Quite possible. I gave the tape a quick look and it seemed okay, but didn't really spend any time checking it properly.

You say about doing the recommended things to do. Does this include a little air in the inner tube before reftting the tyre? Also how are you getting the tyre back on. Pressure from fingers and thumbs only or are you using tyre levers?

The first time I'll admit I didn't put a little air before refitting cause I did it in a hurry, but the second and third times I did. Tyre levers only to take tyre off, fingers and thumbs to put it back on.

Check all around the tyre after it's on and make sure you can see the rim tape and the inner tube is not trapped between tyre and rim anywhere. Getting a flat again within 20 seconds probably isn't a pinch flat unless you felt the wheel grounding as the tyre collapsed flat (which means the tyre structure has failed and must be replaced), unless you really jump up and down on the bike as you pedal. Are you really sure it's a pinch flat and not two sharps stuck in the tyre close together? Are you checking the inside of the tyre where the puncture was or just the outside? Can you try a spare tyre?

Couldn't see anywhere where the tube was trapped and believe me, I was looking for it (as that was what I thought was the cause). The tyre failing is another strong possibility, will see if I can remove the one from my spare bike and try that on my main one. Fairly certain it's not a sharp inside the tyre though - found and got rid of the initial puncture cause on first try (which was on the inside) and managed to ride 40-ish miles home after my roadside change without a problem. Pinch flats only started after I got home and deflated tyre (because I'd filled it via CO2 canister) then reinflated with track pump and even that lasted another 30 miles.

 

[vickster]

I use a lolly stick from a Magnum (white choc is my preferred ) to carefully run round both sides of the rim just to check there's no tube trapped I just keep it with the tyre levers

 

[nickyboy]

Are you able to identify whether the flat occurred at the same place on the wheel (so in all probability a rim tape issue) or same place on the tyre, or randomly?

 

[mjr]

Pinch flats only started after I got home and deflated tyre (because I'd filled it via CO2 canister) then reinflated with track pump and even that lasted another 30 miles.

Are you really sure you've not picked up another deflation-causer after those 30 miles?

 

[Ajax Bay]

each of my last three changes have resulted in pinch flats, two of those happening within 100 yards . . . everything looked okay with the tyre before setting out, only for it to still go "bang fsssssh" within 20 seconds is just aggravating.

First of all, these are not 'pinch flats'. You get these when your tyre is running too low a pressure - and you have yours at 100psi - or hit a pothole really hard, normally combination of the two.
This sounds like either your tyre or the rim tape is causing the puncture. When you remove the punctured tube, you must be able to find the puncture hole. That will show you where to look on the tyre/rim.
Must pre-inflate the inner gently before inserting.

 

[mjr]

When you remove the punctured tube, you must be able to find the puncture hole. That will show you where to look on the tyre/rim.

This is why people suggest lining up the tyre logo with the valve hole - then when the tube's out the tyre and you find the hole, you can trace it back to the matching position on the tyre by holding the valve where the logo is, even if the tyre has slid about now it's no longer held to the rim by the tube.

 

[Racing roadkill]

Your probably making the rookie mistake of not shoving the tube up into the tyre at the valve point, before full inflation. If you've got the tube in, and the tyre back on, gently push the valve upwards and make sure it moves up and down freely, then just check the tyre is properly seated at the valve point before you fully inflate the tube / tyre.

 

[Sbudge]

Hi Steve, I really feel for you on that one. I had a similar trio of them a couple of months back. Turned out it was a thorn that only showed itself at full pressure and rider's weight on the saddle. I found it in the end by removing the tyre completely, turning it inside out and examining every little spec I could see. Took ages but found the little devil and have ridden 100's of km on that tyre since.

 

[dim]

I used to get a few pinch flats when I used the cheap continental tubes .... since switching to Schwalbe tubes, I have not had one (touch wood)