The IKEA Castor Problem: Why Standard 11mm Parts Don't Fit

We turn away IKEA owners every week, and it always feels rude. So here's the full explanation, in writing, of why standard replacement castors won't fit a MARKUS — and how to know what you're dealing with before you order anything from anyone.

The one-millimetre problem

Nearly every office chair sold in Britain uses a castor with an 11mm diameter push-fit stem. It's the de facto universal standard — which is why our Aeten® castors and glides fit chairs from dozens of brands. IKEA, in classic IKEA fashion, designed their own: a 10mm stem. One millimetre narrower.

One millimetre doesn't sound like much. It's the difference between a click and a castor that drops out every time you lift the chair. An 11mm part won't enter a 10mm socket at all; a 10mm part in an 11mm socket just falls back out. There is no adapter we'd put our name to.

How to check what you own

Pull a castor out (firm tug, straight along the stem) and measure the pin across its width. Ruler will do; callipers are better. 11mm — all our parts fit. 10mm — it's IKEA or an IKEA-pattern chair, and you need parts made to that spec.

If you own an IKEA chair

IKEA sells replacement castors for current models via their spare parts desk — honestly, that's your best route. What we'd gently discourage is buying “universal” castors from a marketplace listing that doesn't state the stem size. The number of sad 10mm/11mm mismatches in the world is entirely avoidable.

If you own anything else

Then the whole catalogue opens up: soft PU castors for hard floors (£6.99), heavy-duty chrome castors (£19.99), or steel glides (£17.99) if you'd rather not roll at all. Unsure? Email a photo of your castor pin to info@chairoutlet.co.uk — the free fit-check has been our habit since 2006.