I got the oversized 17 and 19. I had a 6 speed, and it took three big, three small. I guessed that the 7 speed would be 3 big, 4 small but I was wrong - it's the other way around. So I had to cut the 16 to fit on the larger splines. I also had to scavenge the 6 speed spacer that bridges the transition from big spline to small spline - it had an inset built in to take up slack taht I needed to use, and I had to trim it's width to fit the narrower 7 speed spacing. So all in all, I spend $30 ont he freewheels, and $20 on the extra cogs.

Also, the 14T and 13T cogs have built in spacers and they meshed up kinda sloppy - but when I tightened the nut down I kept them straight and it worked out great. This weekend I am going to take it apart for pictures and make a web page explaining what I did and how.

A little pricey, but a NOS Regina corncob is, like, $150 - and this shifts a heckava lot better. I also have a slew of extra cogs so I can change the gearing if I need to.