> > It's hard to get a 26 inch wheel with a narrow rim (at least in
> Europe)-
> > the narrowest I've ever found is 1.5 inch.

There is loads of narrow MTB rims in Europe and in the UK. Wiggle,
Stiff, CRC and all the Internet mail order sell them as do most
mountain bike shops.

A Mavic 317 is one of the most popular rims in cross country MTB,
its 17 mm wide. The 3 denotes the model and the 17 the width, have a
look there is loads of 17, 19, 21 and 23 mill rims. There is loads
of one inch slicks too.