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Supported by The British Army

Maintain the drive chain

Keep your drive chain in the game by learning how to properly adjust its tension.

You will need

  • Rulers
  • Chain tensioning tool
  • Wrench
  • Access to a motorcycle (with the correct manual)

Most motorcycles and scooters will use a chain, called the final drive chain, to transfer the power form the engine to the back wheel, like a push bike. Using a chain makes it easy to fit and maintain, and it can be easily adjusted to change the performance of the motorcycle. The downside of using a chain is that they need to be regularly cleaned, lubricated and tensioned to keep the motorcycle working at its best.

The final drive chain is tensioned by moving the rear axle backwards or forwards. A correctly tensioned final drive chain will stop the chain from jumping off, and reduce road noise and wear on the parts. Tightening the chain too much can be just as dangerous as having it too loose.

Before you begin

  • This activity’s part of a series of short activities in the Scouts Mechanic Activity Badge.
  • Decide how you’ll run these activities. You could run a mechanics activity day with a few vehicles, so small groups can try different tasks on different vehicles at the same time. You could also run the activities as short bases during a meeting (while other activities take place).
  • Decide who’ll run and supervise this activity. All of the practical activities for the Mechanic Badge should be run and supervised by a qualified mechanic (or someone with enough knowledge gained through experience).


These guidelines are generic for modern vehicles. Always check the handbook for the vehicle you’re using or seek advice from a qualified and experienced mechanic.

  1. Secure the motorcycle on a stand if necessary. Check the motorcycle manual for the tension needed in the final drive chain.
  1. Using a ruler, or purpose-made chain tension tool, check the deflection of the chain. This is the maximum distance the chain can move when pushed up and down with your hand in the middle of the chain.
  1. Use a wrench to loosen the rear axle nut. If more force is needed you can use a longer wrench or a wrench extension.
  2. Adjust the axle adjusters in the direction needed, making sure to do this equally on both sides of the wheel to keep the axle straight.
  1. Recheck the chain deflection and continue to adjust the axle until the chain is correctly tensioned.
  1. Tighten the axle nut following the manufacturer’s guidelines. Keep an eye on the axle while doing this to make sure it stays straight.


This activity was all about developing skills. Why’s it useful to be able to get stuck in to vehicle maintenance? It helps keep people safe and can save you money too. It’s also better for the environment to look after vehicles so less resources are used to repair avoidable faults (or even replace cars). Was it easy to learn this skill? Is this skill the same for every single vehicle, or would people still need to check the manual?

This activity also gave people the chance to be independent. How did it feel to get stuck in to a practical task? What role did the adults have in this activity? They supervised to make sure no one (and no vehicles) got hurt.


All activities must be safely managed. Use the safety checklist to help you plan and risk assess your activity. Do a risk assessment and take appropriate steps to reduce risk. Always get approval for the activity and have suitable supervision and an InTouch process.


This task involves the use of potentially harmful fluids or chemicals. Make sure you follow all relevant safety guidance. Make sure you dispose of them appropriately too, in line with safety guidance.

Manufacturer’s guidelines

All vehicles will be different so always follow the manufacturer’s guidelines.


Before completing this activity make sure you have suitable personal protective equipment (PPE). This could include eye or ear protection, gloves, and anything else you need to protect yourself. You’ll know what you need as a result of completing the risk assessment for the activity.

Vehicle readiness

Before completing this activity, make sure that the engine’s fully cooled. The vehicle should be parked on flat, stable ground with the parking brake applied.

Outdoor activities

You must have permission to use the location. Always check the weather forecast and inform parents and carers of any change in venue.