Single-speed bicycle
（重定向自Singlespeed）
![A single-speed mountain bike. The frame was modified by replacing the rear drop-outs with track fork ends to allow the chain to be tensioned.](/Images/godic/202502/11/Single-speed_mountain_bike3225.jpg")
![Old racing bicycle, casually converted to single speed. Note the semi-horizontal drop-outs, and redundant second chainring.](/Images/godic/202502/11/Courier-4593225.JPG")
![Spring-loaded chain tensioner](/Images/godic/202502/11/Kettenspanner_für_Singlespeed-Räder3225.jpg")
![Fixed-position chain tensioner](/Images/godic/202502/11/Planet_X_Stealth_Pro_Track_Bike_I3225.jpg")
A single-speed bicycle is a type of bicycle with a single gear ratio. These bicycles are without derailleur gears, hub gearing or other methods for varying the gear ratio of the bicycle.
There are many types of modern single speed bicycles; BMX bicycles, most bicycles designed for children, cruiser type bicycles, classic commuter bicycles, unicycles, bicycles designed for track racing, fixed-gear road bicycles, and single-speed mountain bikes.