I had to take the adjuster knob off the rear preload adjuster on my 97 R1100GS to unseize it yesterday. As I did so I heard a 'ping' as I lifted the knob off. Yep the bearing fell out, and nope I couldn't find it anywhere.
So I dived into my box of mountain bike parts and found that a 5/32 (approx 4mm) headset bearing fits fine.
Available in bags of 54 for 24p
http://www.gooutdoors.co.uk/weldtite-bearings-5-32-ins-carded-p107336
(Bag them up individually and sell them as an OEM replacement part for £5
)
So I dived into my box of mountain bike parts and found that a 5/32 (approx 4mm) headset bearing fits fine.
Available in bags of 54 for 24p
http://www.gooutdoors.co.uk/weldtite-bearings-5-32-ins-carded-p107336
(Bag them up individually and sell them as an OEM replacement part for £5
)