79pmooney

Bull. Fix gear simply means the chainwheel and hub have no freewheel mechanism between them so they are locked together in whatever ratio it is set up or is selected if here is a choice. The fix gears I have brought to a half dozen Cycle Oregons with all the cogs between 12 and 24 teeth (and bringing as many as five at a time) is just as much a fix gear as what they race on the velodrome. So were the 3-speed Sturmey- Achers that have been around for decades. (You can argue that in heaven with the late Sheldon Brown. Good luck.)

Now, as veganbikes and others have said, you cannot use any form of chain tensioner with a fix gear (unless you swear to the gods above that you will be as dainty as Miss May all the time and never, ever coast even a millisecond. One coast and the devil will promptly fold your derailleur or tensioner into a twisted steel/aluminum sculpture. Probably toss it into your spokes and/ or tweak a stay or dropout. A deep scratch or two. Destroyed rear tire. And one massive heartrate spike.

The core concept to keep in mind with fix gears is that as long as you are rolling, that drivetrain never stops (except by skidding, massive force or something breaking). At usual road speeds and gear ratios, that force is greater than your legs can provide without real damage to you. This means the entire drivetrain should be strong and reliable. (Keeping it simple is a very sound principle.) Also keep everything away from that drivetrain. Loose bungies, rope, clothing, shoelaces, pumps ...) Again, remember, if something falls into it, that something or another something is breaking. No if here.

Says Ben, Mr. Fix Gear, who's done a few unplanned stops in his many miles of fixing.