ยง 1237. Method  of  giving  hand  and  arm  signals by bicyclists. All
  signals herein required to be given by bicyclists by hand and arm  shall
  be  given  in  the  following  manner and such signals shall indicate as
  follows:
1. Left turn. Left hand and arm extended horizontally.
2. Right turn. Left hand and arm extended upward or right hand and arm
  extended horizontally.
3. Stop or decrease speed. Left hand and arm extended downward.
Structure New York Laws
Article 34 - Operation of Bicycles and Play Devices
1231 - Traffic Laws Apply to Persons Riding Bicycles or Skating or Gliding on In-Line Skates.
1236 - Lamps and Other Equipment on Bicycles.
1237 - Method of Giving Hand and Arm Signals by Bicyclists.
1239 - Reflective Material and Devices for In-Line Skating.
1242 - Additional Provisions Applicable to Bicycles With Electric Assist.
1242-A - Operation of a Bicycle With Electric Assist While Under the Influence of Alcohol or Drugs.
1243 - Shared Bicycle and Shared Bicycle With Electric Assist Systems; Data Protection.