120 is the accepted BCD, although I think one edition of Sutherland's actually listed it as 119. Is is definitely larger than the 118 BCD found on many Japanese SR brand road cranks, and definitely smaller than the 122 BCD old Stronglight, as years ago I tried those rings on a Zeus crank to see if they would fit. Some years ago I experimented with filing down the inside of a 118 SR brand ring and slightly enlarging its chainbolt holes to make it fit a Zeus arm. I was able to mount it, but the thickess of metal between the bolt hole and the spider was so thin that I was afraid to ride it. Besides, soon thereafter BC started turning up NOS Zeus rings at reasonable prices in Holland.
I've never seen another brand of chainring with the Zeus circle, though I won't swear there wasn't some really obscure Spanish knockoff. BTW, 120 wasn't the only Zeus circle. The Zeus Competition, which I think probably gave its name to the original Raleigh Competition on which it appeared, used a large ring compatible with TA Cyclotourist and Stronglight 49, among others, but the inner ring was 151 BCD like the early 60's pre-NR Campy Record.
Too bad Zeus didn't make the circle 2mm larger so they'd at least be compatible with the old Stronglight.
One other piece of Zeus crank trivia - the extractor thread was 22mm like Campy, but Zeus used 16mm crank bolt heads like Stronglight. This means you need a really thin walled socket to remove the crank bolts. Lots of people replace Zeus crank bolts with Campy 15mm ones, but I take great pride in retaining the original 16mm bolts. Of course, I have a couple of thin walled Zeus crank bolt wrenches.
Jerry Moos Houston, TX
Amir Avitzur <firstname.lastname@example.org> wrote: I just tried to measure the BCD of a Zeus chainring with pencil, paper and ruler, but did not get a consistent BCR ... the radius is either 59 or 60 mm.
Sutherland's 3rd edition sais 120. Zeus Catalogue 102 is no help
Does anybody have a definitive measurement? Were there ever any non-Zeus inter-changeable chainrings?
Amir Avitzur Ramat-Gan, Israel
BTW: Anybody out there with a good 36T to sell or trade? BTW #2: Eddy Mercks will be participating in this weekend's Eilat Triathalon.