The Phantom Gear chain tensioner page
The phantom gear or P-gear method of chain tensioning is done by inserting a cog or chainring in between the top and bottom chainlines and is the method of tensioning I use on my singlespeed stock trials bike. The problem with most stock frames for singlespeed is that there is no way to adjust chain tension. Since the main advantage for running a singlespeed setup is the elimination of weight and complexity of deraileur and assocated components, usng a chain tensioner or a deraileur on a singlespeed setup hub defeats the whole idea of singlespeed. Singlespeed is simplicity, and we need to use simple lightweight methods for the best setup. Enter the P-gear. This design is a single part with no pieces to fail, there is little stress on a P-gear which means we can make it really light, and best of all, when installed properly, is silent and invisible. I've found this is a major pimp factor part and everyone who sees it thinks it's pretty trick. All this and it works, flawlessly!