I would suggest that Sheldon is generous in his description of the Atom rear drum brake for tandems. Three problem areas to watch for:
1) Hub is narrow, bearings pretty far in, weight is high. Prescription for bent axles.
2) Drilling varied, but frequently done for oversized wheelchair spokes. Installing modern high quality spokes requires drilling new holes between the old ones, and leaves you with 36 spoke wheels (I can't remember drillings other than 36, except for an acquaintance who laced his with 71).
3) Sometimes came with French FW thread, which means all but unobtanium unless Harris Cyclery has a stash. The Bonus: 4) If memory serves, axle was oversized, with unusual threading. Cones were lathe-turned, not ground, and pitted easily.
I much preferred the Shimano "E," a true disc brake that worked at least as well.
harvey sachs mcLean va (I think I still have examples of the Atom, Shimano, and Phil Wood tandem brakes, but pretty much out of that game now)
Don Wilson wrote:
>>Could someone take a look at these Super Champion
>>rim/hum set and tell me if the rear "drum" hub that
>>the seller refers to is an example of a drum brake for
>>a tandem? If it is, do you use that rear drum brake in
>>the hub in combination with cantilever brakes on the
>>rear wheel rim for increased stopping power due to the
>>weight of two folks on a tandem? Finally, would these
>>rims/hubs make a nice set of rims/hubs for my old
>>Gitane tandem that lacks a hub brake? Its Modolo rear
>>brake lever has seats for two cables.
>>http://ebay.com/<blah>
>
>
That's an Atom drum brake. These were common for tandems in the '70s. (The ad says: "marked Brevete SGDG" which means "patented inc.")
These were not wonderful brakes, but not terrible either.
However I very strongly advise against using a single lever to control two brakes. Best way to use a drum brake on a tantrum is as a "drag brake" with some sort of derailer shift lever.
See my article on Tandem Brakes for details on this:
http://sheldonbrown.com/
Sheldon "One Brake, One Lever" Brown