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.
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Winds of nearly 80mph have been reported at Avonmouth as Storm Imogen arrives in the west.
After a weekend of heavy rain and high winds, the West Country has been told to brace for another bout of bad weather.
Around 500 people marched through the centre of Bristol protesting against government plans to bring in new contracts for junior drs.