Originally Posted by
sillygolem
Note that you can buy a 14t freewheel, but it will be metric thread. Your bike uses ISO thread. The only way to get a larger gear on your freewheel side is to use a larger chainwheel.
You could, in theory, rebuild the rear wheel with a BMX flip flop hub, replace the axle with a longer one and space it out to 120-130 mm (depending on the frame), and install a 14T metric freewheel. But thats a whole lot more complex than just installing a larger chainring or using a 14T track cog.