ColinL . . . doooh! yea I should have thought of Sheldons site. . . Thank you for reminding me of such an obvious solution.

The spacer route is one I have used in the past but, I was wondering if like 9 speed freehub bodies there is a conversion kit available for 7, Surly do a good one, that is nine speed but could well do 7, and I have one of their rear cogs, 19 t this thing is thick and should go the distance.

Small Parts | Parts and Accessories | Surly Bikes

heuyhoolihan, Thanks for the info and chain ring rear cog no's I plan to run 38-19 which should give good chain tension. I used this on a Marin a while ago and also 34-18 works well on vertical drop outs with no need for tension er.

Thank you both for the posts I will now get to work.