Chain Tensioner STR8 Derbi 15mm Blue (x2)

Chain Tensioner

We carry a wide selection of chain tensioners for 50cc motorcycles, mopeds and motocross bikes.

Motorcycle Chain Tensioner

It's best to follow the instructions in your vehicle's owner's manual.

A chain that is too loose tends to "rattle" and can even jump out of its guide. A chain that is too tight can cause premature wear (the chain will stretch over time) or even break. When the shock absorber is compressed, the chain becomes taut. when impacting hard, such as it happens in motocross, a chain that is too tight would not withstand the stress.

If you no longer have a manual, you can check the tension of the chain as follows:

1. Jack up the motorcycle on the center stand or a bike jack, the rear wheel must be free to move.
2. Press the chain against the swingarm from below, approximately halfway between the sprocket and the chainring.
3. The chain should then be tensioned above the swingarm.

You can use chain tensioners to adjust the chain slack by moving the rear sprocket forward or backward. The tension can be adjusted as follows:

• If the chain is already taut before you push it under the swingarm, you will need to loosen it: adjust the chain tensioners so that the wheel axle is pushed forward (bring the rear sprocket closer to the front sprocket)
• If the chain is not taut when you push it under the swingarm, you need to tighten it: Adjust the chain tensioners so that they move backward (move the rear sprocket away from the front sprocket)

Different types of chain tensioners

There are chain tensioners with detents, you can often find this type on older motorcycles. These tensioners are fixed to the wheel axle and must be rotated to adjust the tension.
On modern motorcycles, you will find chain tensioners that slide into the swingarm and are tensioned with a bolt.

Original chain tensioners are usually made of aluminum, but there are also anodized custom models and racing versions where you can change the gear ratio in an instant thanks to their asymmetrical shape.