I think editor skills are a perfect example of bicycle skills. When you're effectively editing text all day long, learning an editor like vim or emacs really pays off in the long run, although it might be painful in the beginning.

Bash scripting is another bicycle skill I think. The power of automating tasks is obvious but often it's easier to just type stuff in quickly rather than writing a script and let the machine handle the job.

There are probably many many more, but those just popped into my mind right after reading the definition of a bicycle skill.