Originally Posted by
Road Fan
Your ideal chainwheels would be a 39/52, given that freewheel, and that you want the 100 inch top gear. For Jimmuller's freewheel it would be a 42/52.
For half-step in both cases, 47/52 for Sailor's and 48/52 for Jimmuller's old Peugeot.
I don't know what you mean by "idea", but I rode a lot of miles with that combination. Often I wished I had a lower gear too! I recall seeing it described as "Alpine" but that could mean different things to different people. But I do recall working out the ratios and plotting them on a log scale and they were indeed 1 and a 1/2 step. Which is to say when you shifted chainrings the new values bisected the spacing of the other chainrings, shifted one full gear. I never rode it that way anyway so it didn't matter.