Do you have a single speed specific bike with horizontal drop outs, but you'd like to convert it for geared riding? There are few potential solutions, but the simplest might be the DMR Chain Tug and Mechanical Hanger. You can use it to replace your regular chain tensioner and it also serves as a derailleur hanger, essentially converting your horizontal drop outs into traditional ones. After the new hanger is installed you simply add the derailleur and shifter of your choice. Remember that if you're running a single speed specific hub you'll need to get a new multi-gear wheel or rebuild the existing wheel with a new freehub. Also, if your frame doesn't have braze-ons to run shifter cables we have aftermarket cable guides in stock that zip tie on to your frame.