It is a celebration of old fashioned values as up to 400 ladies and gentlemen cycle through central London in high fashion and on a range of antique velocipedes.
You need permission to cycle along with them - and all the tickets have been allocated. Although the exact route is not published in advance (why?) the following viewing points are suggested (times are approximate):
12:00 Marylebone High Street
12:30 Regent Street / Savile Row
13:00 Piccadilly Circus
13:30 Houses of Parliament
14:00 Trafalgar Square
More information on the Tweed Run website at http://tweedrun.com/.