Hi Colin, I’d have to agree with Scott re: functionality. I’ve been plagued with injuries resulting from very flat feet. However hiking with a good amount of ascent seems to be as beneficial to me as running. I’d typically walk hard or scramble fast uphill and jog at a steady pace down…I’ve raced at a high level in fell and mountain running and had success against runners averaging 70+ miles a week vs my 25miles of walk/jog with 4000m climb. Cycling will maintain cardiovascular fitness but will not prepare you for descending or carrying load.
Hope this helps.