Originally Posted by n4zou

You can run that three speed with a triple crank. You need to find a narrow cog that will fit the three-speed hub. I removed my stock cog and put it on a metal lathe and thinned the cog teeth and filed them by hand to get the tooth profile correct after machining. I did see another setup like that and the stock cog was thin enough to work properly with 3/32 chain. Just put your narrow chain over it and check to see if it will fit. You will need a clamp on rear derailleur to take up chain slack. Just use the limit screws to lock it in position with the cog. A cheap big box retailer bike derailleur will work fine. I use a 48-38-28 crank with excellent results. Granted, it's not what you would normally find on a "classic" 3-speed bike but you will love the extended range of gearing available.