Wheel building for polo

Screw on freewheel you mean?

Trials hubs.

Some double sided, some with disc mounts - http://www.tartybikes.co.uk/135mm_fixed_hubs/c21.html

bit pricy and possibly overkill

If not trials, specialists like Surly:

http://www.charliethebikemonger.com/surly-rear-hubs-917-p.asp

Could also go eccentric:

http://www.charliethebikemonger.com/white-industries-eno-eccentric-rear-hub-1366-p.asp

surly is sold out and the WI is only 32h. looks proper sweet though!

stay away from surly hubs. bearings are useless, and will just bring problems.

gotcha, thanks

Surly use adjustable thrust bearings in a standard size. You will ruin then if (like I did) you don't know to adjust the play out. Almost nowhere stocks the angular thrust 7901and will try to sell you the 6901, straight bearing in the same size casing. The straight bearing won't support the same axial loads as the 7901 so you'll kill them.

... Yeah

I like my DMR revolvers.

these look like the winner. affordable and reputable??