Originally Posted by
77Univega
Has anyone had success with adding a front derailleur onto a 3-speed bicycle with a rear in-hub shifter (like a Sturmey Archer) thus creating a transmission with six usable gears?
I'm pretty sure that someone has tried just about anything you could think up. Bicycles do lend themselves to the fun of mechanical experimentation. If someone bothers to put a chain tensioner on back, the next logical step would be to add some cogs for it to shift.
The 1/8th inch chain three cog 15-19-23 was made to yield five useable gears with next to nothing gained by double shifting, because all of the interior ratios are basically duplicated.
You get ratios of:
39-46-63-84-107
If you regard the three speed hub ratios as if they were a triple front, it would be like having 35T-46T-62T chainrings.
For example, with a five speed freewheel 14-16-19-22-26 without double shifting you get 7 gears:
35-46-54-63-75-85-115
Greg