Just the Right Amount of Tight : Why You Want a Torque Wrench and How to Use It!
Have you ever had a creaky seat, or a shifter lever come loose during a ride? Join the club! If you haven’t tightened nuts and bolts on your bike properly or haven’t done a bolt check in a long time, those fasteners can come loose and cause some serious problems for you out on the road or trail (or at least cause some seriously annoying noises). So, how do know when you’ve tightened your bike’s bolts enough and prevent over-tightening?
It’s all about TORQUE!
What is Torque?
Torque is rotational force and can be measured in inch-pounds (in-lb), foot-pounds (ft-lb) or, most commonly, in Newton-meters (Nm). When you tighten a threaded fastener (like the nuts and bolts on your bike), it creates tension which holds the joint together. Each fastener on your bike is designed for a certain range of tension, known as a “torque specification”. Often, you can see the recommended torque spec clearly displayed on the side of bike parts, like on your stem or seatpost collar. For other fasteners on your bike, consult your owner’s manual or look up the torque spec online.
Why is Torque Important?
Because every fastener is designed to be loaded with a certain amount of tension, nuts and bolts that are too tight or too loose could cause some big problems during your ride.
Under-tightening nuts and bolts could cause them to come loose while you are riding. The risk caused by bolts coming loose ranges from rattling or clanking bike parts, premature wear to those bike parts, and/or bike parts moving or falling off. This could be a serious issue and could even result in a crash.
Over-tightening nuts and bolts could deform the threads or the bike parts they are holding in place, or even cause the bolts or parts to break due to tension. This is an issue particularly with carbon bike frames and parts that can be crushed by too much pressure.
How to Measure Torque
A torque wrench is a tool for measuring a fastener’s resistance to rotation. The only way to be absolutely sure you have tightened the nuts and bolts on your bike adequately is to use a torque wrench. There are two main types:
Beam-Type Torque Wrench: A beam type torque wrench has a simple design and can be used to tighten a wide variety of fasteners. To operate, add the correct bit to the socket of the wrench. With your hand on the handle, tighten until the reading at the end of the pointer matches the torque spec. Always make sure the pointer is at zero at rest. If it’s off, you can use a tool such as a screwdriver between the two beams to bend the pointer back into place.
Click-Type Torque Wrench: A ratcheting click-type torque wrench allows you to select the torque setting from a designated range. Make sure the torque wrench you have will accommodate the torque spec on the fastener you wish to tighten. To operate, add the correct bit to the socket of the wrench. Select the desired torque setting and tighten the fastener until you hear and feel a “click”. Preset torque drivers are operated the same way.
Tips for Using a Torque Wrench
Hold the torque wrench on the end, not near the socket.
Never use a torque wrench to loosen bolts on your bike. Torque wrenches are made to be a measurement tool, not a replacement for your regular set of Allen keys.
If using a torque wrench with multiple torque settings, make sure you return the wrench to zero before storing it.
Make sure you prep the treads of the fastener with some form of lubrication, unless otherwise specified. “Dry” threads could result in a false reading.
As always, make sure the bolt you are tightening is threaded properly. A cross-threaded bolt will be impossible to tighten correctly, even with a torque wrench.