Originally Posted by
Wildwood
Your best guess as to the year or model of the frame in question? Researching specifics on the Zeus has been a challenge.
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Wildwood, this is a 1970-1973 Zeus Competition Ref Z-52 frame ~60cm. As I mentioned above, the 3 main tubes on these frames were butted metric Reynolds 531 with a 1.0mm x 0.7mm wall thickness. Back then Reynolds called this their "Sprint" tube set.
The wall thicknesses of these tubes were about the same as heavy gage Columbus SP tubing.
Back then a lot of production frames were made with these heavier gage tubes because it lessened the chance overheating the tubes when brazed by less experienced employees.
The forks and stays were Durifort tubing which was about 2/3rds the strength of the alloy steels used in Reynolds 531, Columbus and 4130.
As an aside, Durifort butted main tubes had a wall thickness of 1.1mm x 0.7mm, slightly heavier than Reynolds 531 Sprint and Columbus SP. the next Zeus model down from the Competition plus the P66 Cyclocross bikes were made with all Durifort tubes.
After 1974 Zeus started making all Reynolds 531 frames with long point cutout lugs. They also switched from Cinelli style sloping crowns to the then new investment cast Zeus 2000 crowns. The overall cosmetics improved too.
Some Zeus components were much better quality than the contemporary Campangnolo parts. The Zeus Gran Sport ref 61 headsets for example. We compared the cup and crown race hardnesses between Campy Record and Zeus. Some Campy headsets were only 48Rc while all of the Zeus bearing races were 60Rc.
Zeus used stronger hub axles than Campy. We saw a lot of bent or broken Campy rear axles in the mid 70's. Zeus and Campy axles, cones, spacers and lock nuts were that same size except for the threads. Campy use bastardo 10mm x 24TPI thread while Zeus was industry standard 10mm x 1mm. We just replaced the whole axles with Zeus for customers who were having problems with their Campy rear hubs.
Zeus pedals came standard with alloy cages at half the price of Campy steel cage pedals. They had rubber O-Ring seals on the threaded end too.
Zeus Criterium fluted 2 bolt seatposts came out before Campy SR and were 1/3rd the price.
The first Zeus ad below states Reynolds 531 frame but the second one lists Reynolds/Durifort frames.
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