I have been trying to decide on correct cranks for a couple of circa 1950 frames. I'd like to use aluminum rings, which appeared on the high-end bikes in 1950, even though arms were usually still steel.
One type of alloy ring that was definitely available in 1950 was the six-hole 157 BCD, including Simplex and Stronglight. These used chainring "carriers" to attach the rings to three arm 116 BCD cottered cranks. The cranks were usually threaded for the bolts which attached the carrier to the arm. This arrangement looks elegant, but I think the 157 mm bolt circle limits the small ring to 46 or 47 tooth, not exactly great for climbing, especially for us old farts.
One can obviously get a smaller ring with the three hole alloy 116 BCD rings that attach directly to 116 BCD steel cottered cranks without use of chainring carriers. I think someone in a recent thread referred to these as "sleeve type" rings, since they usually use a "sleeve" which inserts through an unthreaded hole on the crankarm from behind (like modern 5-arm cranks) rather than using threaded holes in the crankarm. I think it was mentioned that the 3-arm steel cranks were often drilled out smooth to accept such sleeves in order to use these rings. However, I have one Stronglight steel crank with a 116 BCD 3-hole ring attached still using the threaded holes in the arms. It's only one ring however. Not sure they made longer chainring bolts for attaching double rings like this, and if they did, they would probably be very difficult to find now.
My question is when did the 3-hole 116 BCD alloy rings become available? Would these have been around in 1950?
Also, I recently saw on eBay a pair of cottered steel Stronglight 5-pin 50.4 BCD arms, the same bolt circle as the alloy cotterless Stronglight 49D, TA cyclotourist, etc. Assuming these were available in 1950, what rings did they use? Were the 49D alloy rings available in 1949? What about TA Cyclotourist? When were the alloy 49D arms themselves introduced? Was it really 1949, or is that just another popular legend? The cottered steel arms on eBay were described a 49A (the A presumably meaning "acier" -steel). Is this correct, or was the 49A a cotterless steel crank?
Finally, its been stated here, whether correctly or not, that the TA cyclotourist rings were introduced much ealier than the arms, supposedly explaining the TA rings on 49D arms so frequnetly seen on 50's and 60's Herses, Singers and other constructeur touring bikes. Anyone know for sure what year the ring were introduced and what year the arms?
Regards,
Jerry Moos
Big Spring, TX