It’s both surprising, and not, if you think about it. The way I’ve usually seen it happen is first the rear tire goes flat, then the front one. My theory is that both tires went through the same pile of glass/thorns/metal bits and they both picked up junk. the reason for the flat occurring on the back first is because there’s more weight on that tire, so the offending article works its way through the tread more quickly.
Spare tube: Sometimes, a tube is just too damaged to be patched, or has had a failure such as the valve stem breaking off which isn’t something that can be patched. To save weight and space, I usually keep a lightweight version of the right size tube for my bike. Since one of the first things I do with most bikes that I own is switch them over to heavy-duty thorn resistant tubes, I just take one of the originals and put that in the toolkit.
We spoke to a broad spectrum of cyclists—from a pro racer to a bike messenger turned mechanic to a touring cyclist who has logged thousands of miles throughout Europe—to find out what items they find indispensable. We sorted through 40 tire levers, almost 30 different kinds of patches, 120 different hand pumps, and 57 seat bags before we narrowed our choices for testing. And then we changed and patched tires more than 50 times, using four different bikes, five different wheels, six different tires, and almost 10 different sizes of tubes. After 96 hours of combined testing, we agree these essentials are some of the best you can buy.
Whether you ride a single, 7, or 10 speed bike or anything in between, you will need a slightly different chain. The major difference is that they come in varying widths to accomodate the different spaces between the gears, but quality of construction is also a factor in choosing a chain. Inspecing the chain should be a part of your regular cycle maintenance procedure- It’s important to keep a chain well lubricated, but oil will also attract dirt and so different oils for specific riding conditions are available. Remember to clean your chain regularly to get the longest life out of it and the gears.