Inner tube and patches
Good winter tyres (here’s our buyer’s guide) will go some way to reducing the likelihood of a puncture but it’s going to happen at some point and, in reality, it’s the most likely mechanical you’re likely to suffer while out on the road.
We normally keep one inner tube in a saddlebag and another back-up tube on our person in a jersey pocket. Keep the tube in a small plastic bag (a sandwich bag will do) to protect it from anything else that’s in your saddlebag.
Having a puncture repair kit (we recommend glueless patches) will get you out of trouble if both tubes fail. We rarely repair tubes at the roadside but they take up very little room in a saddlebag and can be called upon if required.
You also need a means to pump up the inner tube so don’t forget to take a pump. This can easily be stowed in a jersey pocket but a frame pump is a good idea in winter. That way you won’t forget it and the larger volume allows you to pump your tyre up to a greater pressure, in less time.
As a side note, if you replace an inner tube then take it with you and don’t leave it at the roadside.