This has been put together by Instography using data from several sources -
"Compared with the average datazone, the purple areas show where cycling is likely to be below average (1-9%) and the green areas show where the analysis suggests cycling is above average – between 13% and 28% of adults cycling."
This is where people answering questions about the amount they cycle live - not where they cycle. The Pentlands are green because (from a tiny number of households) an above average number cycle.