I bought some of On-One's 'centre lock' wheels from here:-
http://www.on-one-shop.co.uk/acatalog/Online_Catalogue_29er_MTB_280.html

Then i bought some Shimano 'centre lock' rotors like these:-
http://www.on-one-shop.co.uk/acatalog/Online_Catalogue_29er_MTB_280.html

Turns out there a 2 different types of centre lock splines, the big chunky ones on the wheels & the reet fine ones on the discs.

Can someone point me in the direction of the right disc rotors please? The pictures on crc'c website ony show the lockring, not the actual bit on the disc.

I never new there was 2 types. My bros wheels are cebrelock and I have tried a few disks on it. I thought it would be a standard thing.

There's a larger system to fit 20mm axled hubs if that helps.

You want some of these.
Clicky

I've got 2 oversize 160mm centrelock rotors with the lockrings if your interested, these are the ones that fit the 'chunky' oversize hubs… £15 posted the pair. Mail me if interested..

What's wrong with 6 bolts? Grrr.

There's no larger system for 20mm hubs. Just a different lockring which comes with the hub. The splines are exactly the same on all centerlock discs/hubs.

Got pics of the splines on your kit?

The older Saint style CL rotors use a larger a diameter spline – which was only used on the old Saint M800 hubs (and a few others – On-One). All the new/current Shimano 15mm/20mm use the same diameter style now.

I Have some of the wheels you are talking about. They are the latest one On One are selling, the ones that came with t Small block 8 tyre and tube deals. Mine have some adaptors that convert them up to the normal size centre lock disc size. Also standard centre lock disc lock rings wont fit the wheelset! You need the ones specific to the hubs. Did you buy them new> I bought mine second hand but the guy who I got them off had only just bought them from On One. I presume they should come with the adaptor that steps the hub up to the standard centre lock rotor size and the un standard lock ring size. If not I doubt you will get them anywhere else as they must be specific to the wheels! When I fitted my discs the lockring adaptor pressed into the centre lock disc and it was a really really tight fit. I doubt it will ever come out.

Decent wheels but this system is so stupid having to use stupid adaptors and non standard lockrings. If you loose or break them you will be stuffed. It also makes the hub heavier then it needs to be. I would like to know why On One made them them this? I cant see any reason at all.

"I would like to know why On One made them them this? I cant see any reason at all"

ordered the wrong standard & realised too late to change ??

Wrong standard! Maybe thats why they were doing a full wheel build and 2 Small block 8 tyres and tubes for 100 quid over the last month or so. Price has gone to 150 quid over the last week. I would have ordered another set but postage at £15 is way above other sites. Not worth £165 with the postage due to the stupid disk fitting IMO! I have never seen this style of fitting for a brake, I doubt 99.9% of the people who buy them will have. Poor communication not to mention it on the site!

I have got the wheels too, agree with seth-enslow666, they take a standard centre lock rotor using the adaptor that comes with the wheels(remove the rubber strip to expose the splines) however you use the lockring that came with the hub rather than the one with the rotor.

I initially was planning to use some Hope C2 with them but couldn't get the on-one six bolt adaptor to work with them it hit the caliper when the lock ring was installed, others seem to have got it to work. See this thread