The headset on my daily commuter is foobared. So I'll be looking to service it, possibly replace as many of the low-end components with better ones.

As I've learned the hard way, it's the questions you DON'T know to ask that really burn you if you go out and buy a bunch of parts without the full info.

The frame manufacturer's specs are virtually non-existent, which is pretty much to be expected for this cheap frame.

What info / measurements do I need to know in order to replace my headset, and, how do I acquire this information (ie: what are the critical spcs and how do I measure / determine them on my own)?

1 Answer 1


You gotta know your SHIS! :P

First you will need to determine the type of headset you require. It may be integrated,zero stack, External cup,as well as threaded or threadless.

After having this information the measurements you will require are Inside Diameter of the head tube top and bottom. This measurement allows you to determine what type of fork you need, whether 1-1/8" , 1-1/4" or tapered from 1-1/8" to 1.5".

The measurement of the steer tube Outer Diameter on the fork, top (stem clamp 1-1/8" or 1") and the bottom OD (Crown Race Seat Diameter). Bearing seat and angle will also be needed if it is a threadless headset. You can usually just look at the old bearing to get this information if the side marking are still readable.

Cane Creek and Park Tools website both have a plethora of information regarding it. This poster from cane creek may help clarify.

Headset Identification

See the larger version here Cane Creek's wording:

The system addresses the critical interface dimensions required to fit a fork to a frame, as well as bearing location/cup type. To determine fit, four dimensions are needed: (1) stem-clamp diameter of fork, (2) crown-race seat diameter of fork, (3) head-tube top inside diameter, and (4) head-tube bottom inside diameter. Bearing location and cup-type are identified as (a) external cup (EC), (b) semi-integrated or ZeroStack (ZS), or (c) integrated (IS).

More info:

Park Tool Cane Creek

  • 2
    Pretty much right on, with one minor exception. The 1", 1 1/8", 1 1/4", 1 1/2" or tapered measurements refer to the fork steerer tube, not the inside diameter of the head tube. I edited your answer to reflect that. See this answer for clarification: bicycles.stackexchange.com/a/37979/1259
    – zenbike
    Apr 2, 2016 at 6:24
  • Woot! Awesome answer. So it's looking like I'm dealing with (best guess) an integrated, threadless system, as I can't see any means of removing the bearings without a tool and there are no notches or anything on the bearings to suggest that you would thread / unthread them.
    – Tom Auger
    Apr 4, 2016 at 19:22
  • Threadless is the most common these days, Threaded headsets are really only seen on older bikes or newer very inexpensive bikes. Integrated is common and i would say that you are probably on the right track with your thinking. Headsets can be a real pain, simply because there are so many variations. Cane Creek is an awesome company and one of the primary leaders in headsets, they are also great with customer service and will happily help you find just what you need. No i don't work for them :P
    – Nate W
    Apr 4, 2016 at 19:37

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