I need to change my headset bearings, however, there seems to be so many different variations out there, and I'm afraid to order the wrong parts.

Why not just order the same type as the old bearings you might ask? Well, they did not really fit; I think the previous owner just had some random bearings laying around that he used as makeshift replacement parts.

So, I was wondering if anyone here could point me in the right direction? It is an external cup bearing, and the measurements are as follows (measured with a measuring tape, so probably not 100% accurate):

Head tube (inside diameter):

Top: 34mm, Bottom: 34mm

Steerer tube (outside diameter):

Top: 29mm, Bottom: 30mm

Thank you!

  • Are you talking about replacing the headset, or just the bearings in the headset? If the latter, then if they're cartridge bearings, there could be a bearing code on the seal, e.g. 6806 (I think that code or a similar one is a common front hub bearing, it's just one I had in mind). The code should completely specify the bearing size, and you could just get replacements of those. If loose bearings, I don't know.
    – Weiwen Ng
    Mar 12, 2021 at 14:32
  • Please give us photos of the headset and old bearings. We don't know from your post whether they're ball bearings/retainers or cartridges or what. Mar 12, 2021 at 16:24

1 Answer 1


First you have to identify the type of headset. As you said its a external cup headset, but threaded or threadless?

Measuring the outer diameter of the steerer and the inside diameter of the head tube are also a good starting point. But try to measure as acurate as possible. +/- 0.1 mm - 28.6 mm (1 1/8") is pretty standard on the steerer nowadays, so 29 mm seems to be a weird or wrong value.

Replacing only the bearings would be a headache to figure out.

Manufacturers have a standard description of headsets called SHIS (Standardized Headset Identification System). This park tools page should help you a lot to identify the required headset.

You have to figure out the measurements and fit the code together like in the example of the page: ZS44/28.6 | ZS44/30 - you can easily search for this code and find the fitting headset.

Good Luck.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.