As above - get some practice in at home first.

It is always a good idea to try and perform every operation you think you might have to do "in the field" at home and, this is quite important, do it with the tools you're going to carry on the bike. This way you can make sure you've got all the tools you'll need and not end up short of something, as well as making sure you can do the jobs with the smaller tools you might be carrying. For example, it's no use being able to change a tyre with a nice 400mm tyre lever(s) in the shed when you only carry 240mm ones on the bike!

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