Ultegra Cassette and Mavic Aksium hubs

Just installed a new Ultegra 12-27 cassette on my new Mavic Aksiums. I can't seem to get the cogs "tight". At first I thought I left one of the spacers out (i hadn't) or maybe the lock-ring spacer but that also was in...
So when I tighten the lock-ring there is still a small play in the cogs (almost 1mm). I've taken them apart, checked that they're seated correctly and still can't get them tight.

It looks as if i need another spacer?... maybe a wider lock-ring spacer?
Anybody had this problem? Do I add a wider spacer at the back or the front?

Thanks in advance

You didn't mention if it's a 9 or 10 speed cassette. Also what kind of spacer(s) do you currently have on there and where it is it?

yep have had dramas with the aksium combined with 105 10sp cassette (even with spacer installed).

seems to be a recurring problem! I beleive that the free body is too wide (or wider than cassette + spacer. Eeasiest was around this was to CAREFULLY file the outer face of the fee body with a fine file - problem solved instantly.....

but if you dont feel confident, hand it over to someone who knows whats going on.

never had a problem since!

it is a 10 speed.
I understand the wheels should have come with a spacer but the guy i bought them from did not have it...
so my specific question is how big of a spacer do i need to add? the only spacer I have are the ones that came with the Ultegra cassette. I've looked at the mavic web site and it says that i need a mavic HG-CC9 spacer but it does not tell me how thick it is... my guess is that any shimano spacer could work?

You need the standard Shimano 10spd shim (it sounds like you have this one) and the Mavic spacer for fitting a Shimano cassette to a Mavic freehub. I don't think that any Shimano spacer will be the right one, as it is smaller than a 10spd between-sprocket spacer, but larger than the 10spd cassette spacer.
A bike shop charged me A$2 for the Mavic spacer. Ring around.

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I read somewhere that a 3 mm spacer will work also (8 speed spacer) but i would have to remove the shimano spacer that came with the cassette. It appears, from what i've read, the shimano spacer is 1mm and the mavic is 2mm.
I'll be going around to LBS's to see if they have a Mavic spacer; my regular LBS said they did not have one and mavic does not make that a maintenance part anymore (but it was young kid working that day; i'll give it another try)

Well, I answered my own question: One LBS told me i could only use a mavic spacer and he could order one for 14 bucks. Another LBS told me I could use any 2 mm spacer ("Oh, yeah, a spacer is just a spacer") PLUS the 1 mm that came with the shimano cassette, sold it to me for $2.95 and installed it for free. The cassette is now "tight" so hopefully this guy knows his stuff and I won't ruin the cassette. Now that this happened to me, I've seen a ton of similar "issues" in various forums related to Mavic hubs and Shimano cassettes and i can't believe some of "the-off-the wall" answers!

If the locknut threaded and torqued and the cassette is engaged on the freehub splines, there's not much that can go wrong. What you described is exactly what I would expect (LBS has cheap and easy solution). This is really a simple mechanism.