Both of my thumbs up on this one.

Anticipating the rack to be steel, I was a bit skeptical of its performance simply because it was so light. That statement doesn’t really make much sense, but for whatever reason that was my first thought.

I know that if a structure is built correctly it can carry a load much heavier then itself…

I believe that’s the story with the Old Man Mountain racks, -They’re built correctly”
-Info from the oldmanmountain.com- The founder, “Channing Hammond grew up in a metal fabrication shop surrounded by inventors and engineers. His Grandfather was instrumental in engineering and designing Charles Lindbergh's Spirit of St. Louis airplane and his Dad's Bonneville Salt Flats race car (which is driven by his mom at over 300 mph) holds several land speed records. Channing has been doing overnight, backcountry mountain bike trips since he was a teenager.”

The site goes on to talk about how Channing and the gang were looking for something to carry their gear, beside back packs. Not long after looking at their mountain bikes did they realize no racks would mount them. Sounds like he did the logical thing for someone with his background. Fabricate your own rack for you mountain bikes.

So that’s what they deal in at OMM, racks that are crafted to perfection for just about everyone. The “white rack” that OMM sent us has been a great city rack. Not thie biggest baddest on the block, but in my opinion it’ll carry what you need for the daily grind.

Here are the specs…
Old Man Mountain
--white rack--
Load Capacity: 40 lbs.
Weight: 460g
Length x Width x Height
12.75" x 5.0" x 14.25"

And for those skeptical about aluminum racks here is another word from the OMM site. (they said it best)
“Materials & Construction other rack manufacturers have soiled the perception of aluminum by worrying more about profits than reliability. The result is shoddy welding and the use of sub-par grades of material. The right alloy combined with proper construction makes aluminum a truly amazing material. It's used by airline manufacturers and land speed race cars to provide ultimate combination of rigidity and light weight. Our rack material is a bomber grade of Aircraft-grade, 6061-T6, tubular aluminum.
More importantly than the material is the quality of the welds. Our welds are second to none and each joint is welded on both sides, resulting in joints that are far superior to other aluminum racks. The light weight of aluminum also allows us to use a much larger wall thickness than tubular steel racks.”

Also, the videos here are worth a view or two.