Another option I am toying with is using two wheels based around Hope front disc hubs. Bear with me... :) on my Chameleon I have a standard MTB (Mavic) disc/cassette hub - this allows me to use a flip/flop free/fixed arrangement using a drilled cog and the 6 bolt ISO disc mount.
Obviously the O.L.D on a front hub is 100mm but the disc mount face places the drilled cog at a chainline of around 40mm. Because the cog is mounted against the face on six bolts it is easy to space this out with 1mm washers to give a perfect chainline to match the front chainwheel. And nothing is as solid as a fixed cog mounted in this way.
With the O.L.D on a typical track rear end being 120mm it would just be a case of using a replacement axle and a 10mm spacer each side.
Another option I am toying with is using two wheels based around Hope front disc hubs. Bear with me... :) on my Chameleon I have a standard MTB (Mavic) disc/cassette hub - this allows me to use a flip/flop free/fixed arrangement using a drilled cog and the 6 bolt ISO disc mount.
http://myweb.tiscali.co.uk/monsieurpoilu/scc7.jpg
http://myweb.tiscali.co.uk/monsieurpoilu/scc5.jpg
Obviously the O.L.D on a front hub is 100mm but the disc mount face places the drilled cog at a chainline of around 40mm. Because the cog is mounted against the face on six bolts it is easy to space this out with 1mm washers to give a perfect chainline to match the front chainwheel. And nothing is as solid as a fixed cog mounted in this way.
With the O.L.D on a typical track rear end being 120mm it would just be a case of using a replacement axle and a 10mm spacer each side.
Just an idea...