Researched route, not a ridden report, so I'll say up front what's checked and what isn't.

The B3157 runs the Jurassic Coast from Bridport to Weymouth, about 20.4 miles. Single carriageway the whole way, no dual carriageway. Flat out of Bridport, a climb onto the downs to a 600 ft summit on Abbotsbury Hill, then the one real drop into Abbotsbury, then rolling inland through Portesham and Chickerell into a suburban Weymouth finish.

The bit worth knowing before you ride it:

- It isn't the -12% drop that bites, it's Abbotsbury sitting at the bottom of it. You come off the only fast descent on the road straight into a village street, cottages at the edge, no centre line. Not technical, but it's the one place the road can catch you out.
- Two pinches only: the tight hedged lane at about mi 4.6 (a tunnel, no sight past the next bend) and Abbotsbury village.
- Everything else is fast and open. The summit stretch is one of the emptiest bits of coast road in Dorset. Wind matters there and sea fog will sit on it.
- Villages pin it to 30 mph and there is no overtaking through them.

One honesty note: the street-level imagery along the route is stitched from different capture years (2021-2026), so the surface read on the older stretches comes with a date caveat. The character, the verges and the pinches don't move, those are solid.

Full write-up with the surface and verge read, the coverage dates and the grade windows: https://ilands.ai/content/366317662680125440

The route with the map on here: https://www.bestbikingroads.com/motorcycle-roads/united-kingdom/south-west-england/ride/b3157-jurassic-coast-road-bridport-to-weymouth