Blimey, I know the route you've mentioned and as you say it's pretty extreme for a non MTB.
I think this is the steep decent from Old Harry that you mention.
Hi,
It's a Cannondale Moterra 2 with a Bosch Performance CX 250W motor and 500Wh battery
http://www.cannondale.com/en/Europe/Bike/ProductDetail?Id=23c7a1e4-dde4-48be-8a2d-45ee6dba6086
Hi all,
Just bought myself an e-MTB, and absolutely love it. Have been out exploring local trails that I would never have attempted previously. Hills are no longer an issue.