12-32 freewheel cluster? Does anyone manufacture a 12-32 7-speed freewheel cluster to replace the current 13-28 on my 20" Dahon, with a view to touring with panniers?
If that's impossible, &amp; I decide to buy a 20" freehub (cassette) wheel, do I have to specify the hub + cassette width?
I decide to buy a 20" freehub (cassette) wheel, do I have to specify the hub + cassette width?


Yes. Many 7 speed hubs were 126mm between the drop-outs. You may also have a 130mm hub. This is very easy to measure, take the rear wheel out and measure the internal distance between the axle dropouts.

Also be aware that 7 speed hubs used a slightly narrower freehub body (where the cassette slides onto the hub) that later 8 and higher hubs. You can put a 7 speed cassette with a 8+ speed hub with a spacer.