We caught a Puncture Fairy the other day
Sitting in hawthorne hedges throwing twigs
Many cyclists know about Hawthorne. When the spikes dry out after the hedges have been cut, the twigs sit in the road with at least one spike sticking straight up, nicely prepared to get your tyre.
The thorns break off, so they are difficult to see. You have to run a finger around the inside of the tyre and then spend plenty of time pushing the left over bit out.
You'll probably find you've got two punctures as well, as the tube moves after the first puncture and a different part of it gets hit. The thorn just keeps on giving if you don't remove it fully.
Swapping cheap tyres for good ones on new bikes
The nice shiny ones on your new bike are quite likely to be cheap. Check reviews. If you're lucky they might be good ones. If not, the Puncture Fairy will have her best mates with her, just for your benefit. Throw them and get some protected ones.
Sprinkling bad fairy dust on new inner tubes
We once got a new tube out of its packet and discovered it was perished when we inflated it. Another time, we found a new one which had stuck to itself.
Check your spares, they might have been at the cycle shop for a long, long time. There are no sell-by dates on tubes !
Wire bead separation (actually this is Factory Gremlins, not Fairies)
The wire in the tyre bead can sometimes separate from the rubber (we've seen a moulding defect on a new tyre as well). That means the tube can get inbetween the metal wire and the rubber. Hit a bump and the tube gets trapped and punctured.
This once happened three times on a ride, before we figured out what was wrong.
Low inflation pressure (you can't blame fairies for this)
Low pressure can make the tyre easier to penetrate as the glass/thorn etc. can sink in more easily. Also you can get pinch flats. That's where you hit a bump, the tyre moves on the rim, the tube pushes inbetween the tyre and the rim, then you come down again and the tube is trapped, leading to a puncture: a pinch flat.
Valve rubber fatigue (nothing unusual really)
If you've got a slow puncture, check the rubber at the valve seat by bending the valve around a bit while the tube is pumped up. Sometimes that rubber has been worn against the rim valve hole.
Poor or loose rim tape (unusual / unlucky)
There are some weak rim tapes that don't really protect your tube from the spoke holes, even though they appear to cover them. Other tapes can slip up the side of the rim onto the bead seat. That puts the tape inbetween the tyre and the rim in some places. The tyre is supposed to seat on the rim tightly. If the tape interferes, you can get mysterious pinch flat punctures.
Trapped tube during installation (Your fault !)
When you've put a tyre on a rim, be careful not to trap the tube between tyre lever and rim. Then, when the tyre is on, put a small amount of air into the tube and go around the tyre, pulling it away from the rim to check whether the tube is up inside the tyre properly and not trapped between tyre and rim.
Dirt in the valve (Use valve caps)
If you've got a slow puncture and there is dirt in the value, you can probably hear it hissing.
Damaged rims (Bad luck, but you should always check)
Sometimes the inner surfaces of a rim can get damaged or are even just not smooth, particularly near the valve hole. A bit of emery cloth can be used to remove any rough patches.
Hope you found our list useful. We've certainly come across some odd punctures.