Hi Andy!
I am familiar with the Rigida Sputnik. It is probably best-described as the result of a marriage between Rigida's Andra and Grizzly, and is a very nice touring rim...lighter than the Andra and heavier than the Grizzly, with a near-Andra extrusion profile and double ferrules (the grizzly has single ferrules). In other words, a great all-round touring rim if one doesn't own a Rohloff hub that would benefit from angled spoke holes. I would buy and use one for loaded touring without hesitation; it is a very nice rim. I am constantly amazed we don't see it in more common use.
Let's take a look at how they compare in a little matrix:
Width outer Width Inner Sidewall ht. Rim ht. Weight*
Andra 25mm 19mm 13.5mm 20.5mm ~818g
Sputnik 25mm 19mm 13.0mm 19.5mm ~670g
Grizzly 22.7mm 18.8mm 13.5mm 22.0mm ~540g
Plainly, the Andras are built for stout, and have a thick center extrusion running along the spoke line -- so thick, Rigida feel ferrules aren't necessary to add strength. The same center ridge in the spoke well allows for drilling the spoke holes at an angle which aids in spoking the Rohloff's large flange, ensuring the spokes enter the rim straight rather than bending at the ends of the nipples.
The Rigida Sputnik is very similar to the Belgian EXAL S19, but the S19 has a disappearing wear groove in the sidewall, rather than the Sputnik's appearing wear groove (shown in worn-out form here:
http://i161.photobucket.com/albums/t207/andrew_sw/rim1.jpg ). I would prefer the latter 'cos it is failsafe insofar as indicating wear limits and it is designed with a C-shaped cross-section of alu around the wear groove, so the rim can be used with care till it can be (soon!) replaced.
For pics showing each rim in cross-section with measurements, go here:
Andra:
http://www.bikestation.fi/shop/index.php?main_page=popup_image&pID=338Sputnik:
http://www.vakantiefietsshop.nl/1051-1841-thickbox/achterwiel-met-rigida-sputnik-velg.jpgGrizzly:
http://www.jejamescycles.co.uk/product-images-large/rigida-grizzly-mtb-rim-black-51429.jpgI hope this helps, Andy.
All the best,
Dan.
*Weights are approximate from dealer's websites and won't be accurate for close comparison due to differing numbers of spoke holes.