How To: Using a Torque Wrench on Your Mountain Bike

Why Do We Use Torque Wrenches? 

A torque wrench is a tool designed to apply a specific amount "tightness" or torque to a bolt or nut. Stereotypically torque wrenches are designed in the shape of a socket wrench with an internal mechanism that can be externally adjusted for different torque settings. So why do we use torque wrenches on mountain bikes? Just like with cars or airplanes, certain components of the bike need to tightened enough so they don't come loose. At the same time, if a particular component is overtightened, it might damage the part. Having a torque wrench is a great way to quantify exactly how tight bolts are on the torque sensitive areas of your bike. 

Torque Sensitive Areas on Your Mountain Bike

Handlebars and Stem - With lightweight materials like carbon and titanium all over mountain bikes now a days, using a torque wrench has almost become mandatory so that you don't damage those extremely lightweight parts. Once you get in a good habit of using a torque wrench, you will want to use it on just about everything on your bike. One of the most important torque sensitive areas on your mountain bike is the cockpit. With carbon handlebars especially, it's very important not to over tighten the stem clamping bolts that hold the bars in place. Over tightening carbon handlebars can cause them to crack or possibly break. With the Deity Skywire Carbon handlebars for example, Deity recommends a maximum torque range of 4-4.5 Nm. Keep in mind this torque range would be different for different handlebars and manufacturers. 

Suspension Linkage - Another highly torque sensitive area on your full suspension mountain bike is all of the suspension linkage hardware on the frame. It's important that each bolt and linkage axle on the frame is torqued properly that way the suspension system isn't binding or causing premature bearing wear. If some of the linkage hardware is overtightened, the bearings or bushing may be preloaded too much. Even if the suspension system is running smoothly, you may be killing those bearings. With a torque wrench you won't have that problem.  

Derailleur - Some threads and bolts you have to be more careful with than others. Where your derailleur mounts up to the derailleur hanger is one of those spots. Sram is nice enough to put the torque spec right on the outside of the bolt head. On all of the Eagle 12 speed derailleurs, Sram recommends 10-12 Nm. 

Crankset - Another torque sensitive component on your mountain bike is the crankset. Both threaded bottom brackets and crank arms recommend a much higher toque than most other components on your bike. With Sram's new DUB crankset, Sram recommends that the cranks be tightened to 54 Nm. This is where having a higher torque range torque wrench like the Park Tool TW-6.2 comes in handy. While you might not use is as often, they are still handy to have in the tool box. 

Tips on Using Your Torque Wrench

• For the most part, using a torque wrench is pretty simple. Most clicker type torque wrenches use either a 1/4", 3/8", or 1/2" socket drive, that way you can use any attachment available. Whether it is a hex key socket bit or a Park Tool BBT-79 bottom bracket socket tool, there are plenty of standard and speciality tools that will attach to your torque wrench.
• Once you have the correct attachment or bit, next set the correct torque setting on the handle of the torque wrench. If you are working with any torque wrench that is new to you, a good way to be safe is to first dial in the torque setting roughly 20% lower than what is recommended and get a feel for how that particular torque wrench operates. Then you can work your way up to the final torque setting.
• When you are working with multiple fasteners on the same part, for example the stem faceplate or dual crown pinch bolts, it's very important to apply equal torque across those different bolts. When you are tightening the stem bolts that secure your handlebars, again start with a slightly lower torque setting and make sure the faceplate is centered before working your way up to the final torque setting. What you don't want to do is tighten only one bolt at a time all the way down. This might cause the part to bind and then potentially work its way loose once you start riding.
• The last thing you want to do before putting your torque wrench away is placing the torque setting back to zero. This will keep your torque wrench registering more accurately for longer and is a good habit to have.

Which Torque Wrench Should I Buy? 

Here at the shop we are big fans of Park Tool and all of their products. We also sell torque wrenches from brands like Pedros, Ritchey, and Effeto Mariposa Giustaforza, but you can't go wrong with any the different options from Park Tool. Here are some of our favorites that our head mechanic Liam uses every day. 

The Park Tool TW-6.2 is a clicker style torque wrench with a 10-60 Nm range (88-530 Inch Pounds) that uses a 3/8 inch drive socket head. This torque wrench is designed for higher torque applications like threaded bottom brackets, cranksets, center lock brake rotors, etc. The TW-6.2 is both left and right hand thread compatible and includes its own case with Nm to inch pounds conversions. 

The Park Tool TW-5.2 is the younger brother to the TW-6.2 above and offers a 2-14 Nm range (18-124 Inch Pounds) with a 3/8 inch drive socket head. Between the two, the TW-5.2 torque wrench is the one that will get used most of the time on components like stem and handlebar hardware, brake caliper bolts, brake lever mounting hardware, etc. The TW-5.2 is also left and right hand thread compatible and includes its own case. 

The Part Tool ATD-1.2 is an adjustable torque driver that is designed as a quick and easy way to prevent over torquing different fasteners. The ATD-1.2 offers a 4-6 Nm range in .5 Nm increments. This torque driver comes with 3mm, 4mm, 5mm, and T25 bits that store conveniently in the handle. The magnetic sockets securely holds each bit in place when in use. The ATD-1.2 is convenient, easy to use, and works best with seat post clamps, chain guide mounting hardware, and brake lever mounting hardware.