When it comes to bicycle headsets, the sheer number of options can make finding the right one a nightmare. The Standardized Headset Identification System (S.H.I.S.) simplifies the process by providing a consistent method to describe and identify headsets. This guide will explain how S.H.I.S. works and how to use it to choose the correct headset for your bike.

S.H.I.S. uses a combination of codes to describe a headset’s features. The format typically looks like this:

[Upper Type] - [Upper ID] / [Lower Type] - [Lower ID]

Here’s what the components mean:

• Upper Type and Lower Type: Describe how the bearings are housed in the frame (e.g., EC for External Cup, ZS for Zero Stack, IS for Integrated System).

• Upper ID and Lower ID: Indicate the internal diameter (in millimeters) of the head tube where the bearings sit.

Common S.H.I.S. Terms

1. EC (External Cup): Bearings are housed in cups pressed outside the head tube.

2. ZS (Zero Stack): Bearings are housed in cups that sit flush inside the head tube.

3. IS (Integrated System): Bearings sit directly in the head tube without cups.

For example, a typical S.H.I.S. code might look like this:

ZS44/EC49

• ZS44: The upper bearing is a Zero Stack type with a 44mm internal diameter.

• EC49: The lower bearing is an External Cup type with a 49mm internal diameter.

1. Determine Your Head Tube Design

Inspect your bike’s head tube to identify its design. Use calipers to measure the internal and external diameters of the head tube.

• Integrated (IS): Bearings rest directly in bearing seats within the head tube.

• Zero Stack (ZS): Bearings are semi-internal and sit in pressed-in cups.

• External Cup (EC): Bearings are housed in cups external to the head tube.

2. Measure the Head Tube Diameter

Accurate measurements are crucial for selecting the correct headset.

• Use a caliper to measure the inner diameter at the top and bottom of the head tube.

• Measure the outer diameter if your frame uses external cups.

3. Determine the Steerer Tube Type and Diameter

The fork’s steerer tube type will influence compatibility.

• Threaded or Threadless: Determine whether your fork has threads or is smooth.

• Diameter: Common sizes include 1", 1-1/8", and tapered (1-1/8" to 1-1/2").

4. Match to S.H.I.S. Codes

Once you have your measurements, match them to the S.H.I.S. code. Use the following guide:

1. Road Bike with Integrated Bearings

• Frame: Integrated bearing seats.
• Head Tube Diameter: 41mm.
• Fork Steerer Tube: 1-1/8" threadless.
• S.H.I.S. Code: IS41/28.6.

2. Mountain Bike with Tapered Fork and Semi-Internal Bearings

• Frame: Zero Stack head tube.

• Head Tube Diameter: 44mm upper, 56mm lower.

• Fork Steerer Tube: Tapered 1-1/8" to 1-1/2".

• S.H.I.S. Code: ZS44/28.6 | ZS56/40.
  

3. Vintage Bike with External Cup Bearings

• Frame: External cup head tube.

• Head Tube Diameter: 34mm.

• Fork Steerer Tube: 1" threaded.

• S.H.I.S. Code: EC34/30.

Step 1: Check Compatibility

Ensure the headset matches your bike’s head tube dimensions and fork steerer tube.

Step 2: Consider Your Riding Style

• Road Cycling: Focus on lightweight and low-friction options.

• Mountain Biking: Opt for durable, sealed bearings to handle dirt and impact.

• Gravel Bikes: Look for headsets that balance durability and weight.

Step 3: Prioritize Quality

Invest in high-quality headsets from reputable brands like Cane Creek, Chris King, Wolf Tooth and FSA for long-lasting performance.

Challenge: Identifying the Head Tube Type

Solution: Remove the fork and inspect the bearing interface. Use calipers for precise measurements.

Challenge: Compatibility with Tapered Forks

Solution: Use a headset with a larger lower bearing (e.g., ZS56/40) to accommodate the wider base of a tapered fork.

Challenge: Replacing Worn Bearings

Solution: Match the bearing’s dimensions (inner/outer diameter and height) to ensure a proper fit.

1. Remove the Fork: Detach the fork to access the head tube and headset components.

2. Measure the Head Tube: Use calipers to measure the internal diameter (for IS and ZS) or external diameter (for EC).

3. Check Bearing Dimensions: Measure the inner and outer diameters of the bearings.

4. Record Steerer Tube Dimensions: Note the steerer tube diameter and type.

• Calipers: For precise measurements.

• Headset Press: To install cups evenly.

• Crown Race Setter: For fitting the crown race.

• Grease: To reduce friction and prevent corrosion.

• Allen Keys: For securing components.

• Choose Sealed Bearings: These require less maintenance and last longer.

• Opt for Lightweight Materials: Aluminum and titanium headsets reduce weight.

• Match Your Riding Style: Durability for mountain biking; precision for road cycling.

• Pick a Trusted Brand: Reputable manufacturers ensure quality and compatibility.