Help with unusual threaded headset

[djbrd]

I bought a used bike and need to adjust the headset a little, but don't know how to, because it's kind of unusual. The brand is primax misura, and it looks like this: http://hilarystone.com/images/sale%20im ... Misura.jpg
Specifically, I would like to know the purple ring on the top which seems to lock the mechanism in place. I can loosen the locknut only so far, which might be OK, but I can't get to the bearing cup to be able to tighten it a little (assuming there is one - I'm a bit of a noob). The fork moves a little when I brake.
Thanks in advance.

 

[Mercianbloke]

You could email Hilary Stone to see if their boxed example contains instructions?

 

[onegoodbike]

Re:

Hi,

I had one of these a few years back and if memory serves the purple externally threaded ring does act as a traditional headset locknut would, in fact the adjustment process is the same, it's just the parts that look different.

So you loosen this first and then use a spanner carefully on the flats of the large nut below and tighten up slightly, once your happy it's tight enough hold the outer cup in position and tighten the lockring. I believe that the headsets have angled needle bearings within along the same lines as Stronglight/Mavic examples, I found mine to be hassle-free once set properly.

Hope this makes sense/helps. Cheers Matt