Headset standards: read SHIS, EC, ZS and IS as separate interfaces

A headset name is useful only when it belongs to an identified receiving system. Start with the frame model, generation, size and configuration, then record the fork and the installed headset independently. A specification for an original complete bicycle is not automatically a record of what remains installed today. A family name on a top cover is also not enough to establish every hidden component. Preserve the source and date of each declaration instead of merging them into a single apparently complete specification.

This guide helps read those declarations before asking a replacement question. It does not instruct you to loosen the stem, remove the fork, press cups or expose hidden surfaces to obtain a number. Use exact documentation and an existing controlled technical record first. If a reference cannot be identified non-invasively, leave it unresolved for a qualified mechanic. A blank row is more useful than a plausible number borrowed from a similar-looking bicycle because it keeps the missing evidence visible.

An integrated arrangement places the bearing against a shaped support belonging to the frame instead of a separate pressed cup of the EC or ZS kind. That distinction does not mean every component of the assembled headset is integrated into the frame. The upper cover, compression interface and fork-side reference remain independently identified parts or surfaces. Do not confuse an integrated frame bearing seat with an integrated race at the fork crown: they are at different locations and answer different questions.

The code family gives a starting description, not every contact detail. Preserve exact bearing and frame instructions rather than assuming that a familiar family determines all angles, seals or routing. This page deliberately avoids a catalogue of universal replacements. A manufacturer-specific statement can support the named assembly in its own scope without becoming permission to exchange parts between brands. Similar terminology across two sources is a reason to compare their definitions, not a reason to discard the more detailed one.

Nominal identifiers organise interface families; they are not a machining drawing. Park Tool explicitly distinguishes its whole-millimetre SHIS identifiers from exact measurements. Record the original code unchanged beside any separately established observation, its endpoints, method and precision. Never subtract a nominal family number from an instrument reading and call the difference a clearance, interference or allowable tolerance. Those conclusions need an exact applicable specification and qualified physical verification.

A conflicting record should retain both statements. For example, a fictional worksheet might contain an upper family label in one source and an unidentified observed ring diameter in another. That is not yet a contradiction between comparable quantities because the ring may not be the receiving surface. First identify the surface and state. Do not average the numbers, round one to the nearest family or silently substitute the original-build declaration for the installed observation. Missing identity is a substantive limitation, even when the numbers look close.

Next identify the bearing dimensions and its named contact angles. Then separate the crown race from the fork seat, and finally identify the upper and lower external stack endpoints. The existing fork-length and stem/spacer guides cover their narrower geometry questions; this journey does not replace them. The free blank worksheet has general reference spaces rather than a dedicated SHIS form, so use clearly named supplementary paper notes instead of writing a headset code into an unrelated frame-length field.