Bike Torque Specifications

Torque: What is it?

Torque is the measure of a force applied to an object that causes it to rotate about an axis. In cycling, torque is most commonly quoted when describing the recommended force to be used for tightening threaded fasteners, such as bolts and screws. Torque is the product of a force and a distance. For example, when tightening a bolt with a wrench, the torque applied to the bolt is made up of both the force applied to the wrench, and the distance along the wrench that the force is applied. This means that to increase the torque applied to the bolt, there either needs to be an increase in the force applied to the wrench or an increase in the distance that the force is applied (e.g. by using a longer wrench).

Units of torque are made up of both a unit of force and a unit of distance. The most common unit of torque is the newton-metre (Nm), where 1 Nm is a force of 1 newton (N) applied at a distance of 1 metre (m). The most common imperial units of torque are the pound inch (lbs in) and the pound foot (lbs ft), where 1 pound (lbs) of force is applied at a distance of 1 inch (in) and 1 foot (ft) respectively. To easily convert between the common units of torque use our converter tool.

Torque: Why Is It Important?

When applying torque to a threaded fastener, such as a bolt or screw, the threads convert the rotational force into tension, which in turn produces a clamping force. Generally, the greater the torque used, the greater the tension and so the greater the clamping force. The amount of torque used should be enough to prevent the fastener from working loose, but should not be so great that it causes the fastener or components to deform or fail. This largely depends on the size and strength of the bolt or screw and of any components that are being clamped.

Not applying enough torque to threaded fasteners can lead to them working loose with the vibrations and movements of the bike during use. This can lead to creaks and squeaks, can cause damage to components if they repeatedly knock against each other, or if the clamping force is not sufficient components may slip or even come apart completely. However, overtightening is also an issue. Applying too much torque can put a bolt or screw under too much tension and cause it to fail completely or deform the threads so that it is impossible to reach the correct torque in the future. Overtightening can also lead to too much clamping force which can cause components to deform or break. This is especially relevant with carbon components, which can crack due to carbon's more brittle nature.

Torque: How To Use It Correctly

On modern bikes and components the correct torque is sometimes inscribed on, or close to, the fastener - though this is often not the case. To find the correct torque specifications for a bicycle component try using our torque search tool. Fasteners can be tightened to 10% below the specified torque, though it is best not to exceed this value. Where a range of values is specified it is good practice to aim for the center of the range, i.e. for a range of 11-13 Nm, aim for 12 Nm.

The best way to ensure a bolt or screw is tightened to the correct torque is to use a specialised torque wrench. Some people claim to be able to 'feel' the torque they are applying to a fastener using a normal wrench but it's better to play it safe and make sure. Torque wrenches are calibrated so that they indicate when the correct torque has been reached. This is done either through allowing the head of the wrench to move (often accompanied with a click) when a specified torque is reached, or by reading the torque from some sort of guage. There are torque wrenches that are calibrated for a single specific torque but the most popular ones can be adjusted for a range of torque values. Check out a list of some of our favourite torque wrenches.

Whichever torque wrench you use it is important to ensure that the threads of the fastener are clear of dirt or rust. The increased friction from these can increase the force required to turn the bolt/screw and so give a higher torque reading with the torque wrench - leading to under-tightening.