Don't put a large letter in a small pocket.
If you’ve got an important A4 letter to post, don’t roll it up, put it in your coat pocket and then go off on your bike. That’s stupid. In fact, don’t even think about doing it, because that alone is half stupid, and really, even just half stupid people shouldn’t be handling important bank documents.
Beforehand it might seem like the ultimate time-saver, gaining you maybe even 20 seconds by not having to take your rucksack off you back and get the letter out when you arrive at the postbox. But this is time you’ll lose later.
Need those documents resent for you to sign all over again? That’ll be 30 minutes on hold, 10 minutes talking and then 3 working days for the bank to send them to you.