Anchor Road, Canons Road, Canons Way, Lower College Street, Bridge Valley Road, the Portway, some roads around the Cumberland Basin System and others will be closed early morning until mid-afternoon.
The race starts at 09:30 from Anchor Road, Harbourside.
More top news
As a new visitor centre opens, we've had our aerial camera out on the beautiful Clevedon Pier - take a look at these stunning pictures.
Burnham-on-Sea has failed to meet new EU standards for bathing. In recent testing the water quality fell foul of the tighter laws.
Friday will start cloudy with showers and some bright spells. Temperatures could reach 19 or 20 C but with outbreaks of heavy rain later