How do I find out what size bearings I need for my headset?
I’ve got a 2016 Scott scale 960, I had a look inside the headset the other day and the bearings have gone brown and nasty, the bearings are housed in a flimsy and fragile plastic retainer so I don’t know where to start!!

This should help HOPE guide

or you could just look up your bike on the Scott website…

Syncros OE Press Fit / Tapered 1.5″ – 1 1/8″
OD 50/61mm / ID 44/55mm

http://www.fullspeedahead.com/products/cyclocross/headtube-guide/

This should help HOPE guide ….

That just give info on the headset size and the bearings used by HOPE. Doesn’t tell what size bearings are in the OP’s headset.

Russl, I’m guessing the bearings are not loose ball bearings and are angular cartridge bearings?

Take the existing one out and give it a clean. It should have a number stamped on the side type this into a search engine or online bearing shop. If you cannot see a number then you can use this measuring guide:

https://www.bearing-king.co.uk/how-to-measure-a-bearing.php

Most headsets these days will have angular bearings so you will also need to check what angle your bearings are this is missing from the guide above. Common sizes for MTB headsets are 36 or 45 degrees. Make your self a template out of card similar to what blurty posted with cut outs of 36 and 46 degrees and see which matches the profile of your current bearings.

Thanks for the replies, I’ll do as you suggest jairaj and see if there’s anything written on them. Not been having much luck on google, it’s almost like they’d rather sell you a new headset than just the bearings!