A few hours cycling is nothing - when I grew up in the North East of Scotland people from the coastal fishing villages had quite different accents to people from farms maybe 1 km or so inland.

[NB When the BBC did a TV series featuring fishermen from near where I grew up they had to give the show subtitles so it could be understood in the rest of the UK ;-)]

http://en.wikipedia.org/wiki/Trawlermen_%28TV_series%29