Single speed mountain biking is often described as the simplest form of mountain biking as there are no gears to worry about going wrong. The range of single speed mountain bikes is growing but if you want to convert your current hardtail geared mountain bike to a single speed you’ll need a few basic parts.
Doing away with mechs means the chain needs to be shorter and a chain tensioner will need to be used to keep the chain from falling off. This simple device is a jockey wheel on an arm which sits near the rear hub and keeps the chain tight by increasing the distance the chain needs to travel. If using the existing cassette bodied rear hub then a single sprocket will be needed and this will have to be spaced correctly on the cassette body to keep the chain in line with the front chainring.