possible idea for variable speed belt drive

[butterbean]

Mountain bikes have a shifter and an idler which keeps the chain aligned on different gears. I see no reason this can't work with one belt and two front pulleys. I could see it being a problem with 3 or 4 pulleys, but two? Come on.

 

[butterbean]

After thinking about it, the idler pulley is attached to a pivot arm. Putting another pulley at the other end of the pivot arm and using two belts, moving the pivot arm up or down would engage one belt while allowing the other to slip. Not a bad idea, simple to set up and easier than trying to get a derailleur to shift the belt.

 

[butterbean]

I've located a variable pulley that will fit a 5/8 shaft for $67. Not too bad.