Schwinn 213 Parts List, Full Size Hardware Chart, Product Illustration, Assembly Instructions page 13

Assembly Hardware Required:
Step 11: Attach the SEAT RAIL HR WIRE (#19) to the LOWER HR WIRE (#10).
Carefully slide the seat rail assembly onto the receiver on the MAIN UNIT (#13).
CAUTION! Be careful not to pinch the heart rate wires between the seat rail and
the receiver on the main unit. Failure to do so could cause damage to the wires and
cause the heart rate feature not to function. Attach the SEAT RAIL to the MAIN
UNIT (#13) with 3 16mm ALLEN BOLTS (#5) and 3 FLAT WASHERS (#15). Tighten
bolts. Attach the heart rate wire to the rear port on the back of the seat.
Assembly Stage #6
Attach Seat Rail to Main Unit
(3) Allen Bolts 16 mm long (item #5)
(3) Flat Washers (item #15)