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
The Staying Well Service is being launched by South West Ambulance Service to help its employees deal with traumatic and dangerous events.
It's a pretty rather start to the final month of 2015.
It's going to be a dull and damp start to the last month of 2015.