What are the accepted hand signals for cyclists in the UK?
From a UK government website I found the following document (linked from a page about the Highway Code for cyclists).

Signals to other road users (scroll to the bottom for cyclist information)

Essentially there are three signals for cyclists:


Left arm out - "I intend to move in to the left or turn left"
Right arm out - "I intend to move out to the right or turn right"
(Right) arm up and down - "I intend to slow down or stop" (very rarely if ever used...)


In reality you will find only the left and right signalling used by UK cyclists - any other gestures would not be understood by enough other road users to make them worthwhile.