Has anyone ever tried to develop a variable transmission for a bicycle? No, not an automatic shifting transmission, but one that truly has a variable gear ratio? I was just riding and shifting today and it occured to me how intriguing the idea is.

Obviously, it's not currently feasible, or someone would have accomplished this before. But does anyone know of any attempts or the like?


Thanks,
Josh

Yes its been tried lots of times. Ive seen one where the chainring was composed of a series of small cogs which moved radially to alter the ratio.
Its more bother than its worth, and the transmission losses , which may be acceptable in a motorised vehicle, are too great for a cyclist.

Yes, probably every year at every engineering school in the western world. Not one has amounted to a hill of beans yet.