Whitby to Scarborough "cinder track" is still in a bit of state. you need at least a CX bike if not a hardtail mountain bike, and it gets very muddy if there has been rain around, which is a shame as it should be a great route, as its very scenic.
As soon as you venture far from Whitby it gets brutally steep - the NY Moors are very up and down and unrelenting, the man A roads (171 169 174) are busy, particularly in summer and there isnt a road down the bottom of the Esk valley beyond Sleights.
For example this was me trying to pick a not too hilly route to loosen the legs before a sportve, its Ok as far a Grosmont, then you either turn back or face a large climb with 20% gradients. and that was a short route - any major distance and you've got a lot more hills
https://www.strava.com/activities/559809450
The NY Dales have some bigger "trophy" climbs but more flatter stuff in valleys> with some careful route planning you could do a nice circular ride or two from KS which would be less brutal.