EC34/EC37

Compatibility

• A perfect match to our really sweet matching headset spacers, available separately
• The EC34│EC37 headset is designed to fit frames with tapered 34mm/37mm head tubes and two types of fork steerers (see below)
• The “EC” stands for “External Cup” meaning the section of the cup that houses the bearing sits outside of the frame’s head tube.  The “34” stands for the 34mm “skirt” that presses into the top of the head tube, and the “37” stands for the 37mm “skirt” that presses into the bottom of the head tube.
• SHIS specification
  • Upper: EC34/28.6
  • Lower: EC37/30 or EC37/33
    • Can accommodate two types of fork steerers:
      • “Straight 1-⅛” with a 30mm crown race seat
      • “Tapered 1-¼” with a 33mm crown race seat
• Not compatible with carbon forks that have integrated crown race seats
• SHIS definitions on the Park Tools website: here
• Frame/Fork specs:

• Frame upper head tube inside diameter	33.9mm to 33.95mm
  Frame lower head tube inside diameter	36.8mm to 36.95mm
  Fork steerer diameter top section	28.45mm to 28.6mm
  Crown race seat diameter for “straight 1-⅛”	30.015mm to 30.075mm
  Crown race seat diameter for “tapered 1-¼”	33.03mm to 33.09mm

Bearings