Selecting the correct headset can be a daunting task but in this guide we will be giving you all the tools you need to get the right headset for you bike with a few simple measurements. 

But first we need to introduce you to the SHIS! 

SHIS stands for Standardised Headset Identification System and it groups headset sizes using a few simple rules to allow you to identify exactly what headset you need for your bike.

 

How SHIS works

A SHIS code looks like this: ZS44/28.6 EC44/40

The first part of the code is the headset cup type. In our example ZS

EC = External Cup (press-in cup sits outside the head tube)

ZS = Zero Stack (press-in cup sits inside the head tube)

IS = Integrated (bearing sits directly in a machined seat in the frame—no cup)

The second part of the code (in our example ZS44 and EC44) denotes the inner diameter (ID) of your frame's headtube. You can measure this ideally with a Vernier calliper but you can use a tape measure.

Measure both the top and bottom IDs of your frame.

Common sizes: 41/42, 44, 49, 52, 56 to the closest MM

The next part of the code denotes measurements from your fork. We need the upper steerer tube outer diameter (OD) and the crown race seat OD which is the flat part at the bottom of the fork steerer tube where the crown race for the bearing sits.

In our example (ZS44/28.6 and EC44/40)

Common sizes of steerer/crown-race seat diameter in mm

28.6 mm = 1 ⅛" steerer (upper)

30.0 mm = 1 ⅛" crown-race seat (lower for straight 1 ⅛" forks)

34.0 mm = 1 ¼" steerer (upper, rarer)

40.0 mm = 1 ½" crown-race seat (lower for tapered /1  ½" forks)

Complete headsets are written as Upper | Lower.

Example: ZS44/28.6 | EC44/40

 

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The 5-step method to select the correct Hope headset

 

1) Identify each end separately (upper and lower)

Modern bikes are often mixed (e.g., ZS upper, EC lower). You must decode both ends.

 

2) Determine the headset cup type (EC / ZS / IS)

EC (External Cup): You’ll see a visible cup shoulder outside the head tube.

ZS (Zero Stack): The cup presses in and sits flush/recessed; only a thin top cover shows.

IS (Integrated): No cup at all—bearings drop straight into a machined seat in the frame.

Tip: Frames can be ZS up top and EC or ZS down below; carbon road frames are often IS both ends.

 

3) Measure the head-tube bore (ID) at each end

Use a vernier calliper if you can. Typical pairings:

IS41/42 or IS42 (upper on many road frames)

IS52 (common integrated lower for tapered forks)

ZS44 (very common upper on alloy/steel MTB)

ZS56 (common lower on tapered ZS frames)

EC44 (common lower on straight 44 frames)

EC49 (common on 1.5” external frames)

4) Identify your fork steerer diameters

Upper steerer (where the stem clamps): usually 1 ⅛" → 28.6 mm

Lower crown-race seat (where the crown race/ bearing seats):

30.0 mm for straight 1 ⅛" forks

40.0 mm for tapered (1 ⅛" to 1 ½") or straight 1 ½" forks

 

5) Build the two SHIS halves, then match to Hope Pick ’n’ Mix

Put it together:

Upper = [EC/ZS/IS][frame ID at top] / 28.6 (common 1 ⅛” standard)
Lower = [EC/ZS/IS][frame ID at bottom] / 30.0 or 40.0 (fork dependant)

Once you have those two codes, select the Hope top and Hope bottom parts whose product names list the same SHIS. Hope labels each Pick ’n’ Mix cup by SHIS in the title/spec (e.g., “Top – ZS44/28.6”, “Bottom – EC44/40”). Choose the exact matches—done.