If you have a bicycle, you need a torque wrench. Is that really true? The answer is: Absolutely! Not only if you own a noble carbon racer should you get a torque wrench. Anyone who has a bicycle and doesn't want to run to the workshop for every little thing should have one. Why, you will find out here!
There are a few things that absolutely belong to a bicycle. One is a helmet, the second would be a pump. With that, you have the basics covered. A torque wrench with various attachments is also part of the basic equipment if you don't want to damage your bike during simple adjustment work. A bicycle has around 40 screw connections, depending on the type and equipment, and you need to tighten them with the right amount of force. In the past, specifications like "hand-tight" or "with all your might" were often given for screw connections, but today exact numbers are the norm, and the torque wrench measures them.
Why does your bicycle need a torque wrench?
On a bicycle (whether you have a 12-inch children's bike, a high-end carbon racing bike, a 6000-euro full suspension bike, or a city e-bike), there are numerous screw connections. You can tighten the screws by feel. If your fingertip feeling was right, everything should fit.
But if you tighten the screws too loosely , the screw connections simply won't hold. The saddle then constantly slips lower, the handlebar can be turned, or the luggage rack doesn't hold. And if you screw too tightly ... well. Then it goes "crack," and something is broken. There are two possible horror scenarios here. Either the screw eye breaks. Too tightly fastened bicycle parts can also damage the part that is supposed to be clamped. For example, a too tightly fastened stem can cause a carbon handlebar to crack. Similarly, it can also happen with the seat post.
|
Therefore, screw connections on bicycle frames and components often have an imprint that tells you how tight you can tighten a screw. This applies to both the clamp and the part to be clamped! |
You should adhere as precisely as possible to the specified torque when assembling new bicycle parts. Image © Reverse
A torque wrench helps you to precisely adhere to the specified force. This creates reliable connections, but nothing breaks.
Here are some bicycle parts that should be fastened with a torque wrench:
- every carbon part
- handlebars in the stem
- seat posts in the frame
- axles
- attachments
- pedals
- crank arms
This is the torque
To know what a torque wrench can do, and why you need one for your bike, it is helpful to know what torque actually is:
- “Torque” is a term from mechanics, it describes the rotational effect on a body.
- When it comes to bike screwing, it means: Torque is the force with which you pull on a wrench.
- A torque wrench is a tool that measures this force as accurately as possible.
- Occasionally, you will also find the term “tightening torque”, which means the same thing for bicycles.
- The English term for torque is “torque”, you will often find it in connection with torque wrenches and bicycles.
- Torque is measured in Newton meters (abbreviated: Nm).
By the way, you will also find an indication in Newton meters elsewhere in the bicycle world. The force with which an e-bike supports you is also measured in Nm. To give you an idea, here's a comparison: The drive of a simple city e-bike has about 40 to 50 Nm of torque, an eMTB can have 85 Nm and more. You usually tighten a screw on the stem with 3 to 6 Nm.
Torque wrench on a carbon bike or for carbon components
For a carbon bike, you absolutely need a torque wrench, and individual bicycle parts made of carbon should always be fastened with a torque wrench. Carbon frames and carbon components react somewhat sensitively to pinpoint loads, they can break more easily than parts made of aluminum or steel. For this reason, screw connections are particularly tricky here, and you should always use a torque wrench !
In addition to the torque wrench, you should always have a tube of carbon paste in your toolbox for your carbon bike. The connection between the bicycle parts can be significantly improved even with little tightening force. You can learn everything you need to know about carbon assembly paste in the article “What is carbon assembly paste and why do you need it?”.
How a torque wrench works
Somewhere on the torque wrench, you will find a display and the ability to adjust the tool, where you can set the desired torque in Nm.
You set the desired Nm using the twist grip. Image © Topeak
Many torque wrenches work like a ratchet or wrench, they tighten screws in one direction, and they “freewheel” in the other. You can set the torque wrench to “left” or “right” (i.e., clockwise or counterclockwise). This is important, for example, when installing pedals.
This is how you use the torque wrench correctly on the bicycle:
- Find the allowed tightening torque on the bicycle part you want to install
- Set the Nm on the torque wrench
- Set it to the desired rotation direction, left or right
- Insert the appropriate bit
- Insert the screw by hand first and tighten it slightly with your fingers, you will notice if it is misaligned
- If the screw sits properly in the thread, you can tighten it on the bicycle with the torque wrench
- When the required torque is reached, the torque wrench will click, or it will “crack” while you turn it
|
The golden rule of the torque wrench: When the allowed (or desired or set) torque is reached, and the torque wrench cracks, you should IMMEDIATELY stop pulling on it! |
To relieve the spring inside the torque wrench, you need to set it to “zero” while it waits for its next use in the toolbox.
What torque wrenches are available for bicycle work?
Simple, affordable torque wrenches
There are very simple and very affordable torque wrenches that at least give an indication of how tight you have tightened a screw. For carbon parts, they are rather not recommended!
This torque wrench is “very basic,” but it does what it should! Image © Topeak
Digital torque wrenches
On a torque wrench with a digital display, you can set the torque particularly easily and precisely. Their disadvantage is obvious: You need batteries!
The luxury version for true bicycle enthusiasts: The torque wrench with a digital display. Image © Topeak
The "normal" torque wrench for bicycles
Mechanical torque wrenches are widespread and they don't cost a fortune. Many of them have a rotating handle, through which you set the torque and a display that tells you what torque your tool is set to. There is a head, where the required bits are inserted.
Mechanical torque wrenches are perfectly suited for most bicycle work! Image © Park Tool
The mega set for all eventualities
Plenty of bits are one thing. Extensions (i.e., bit holders with a handle) are another. A comprehensive torque wrench set includes many practical parts that make working on the bike easier. Such a set is, of course, less practical for on the go.
For many leisure bikers, this set may be oversized. But for those who like to tinker with their bike, this set has everything they need! Image © Topeak
Compact torque wrenches for on the go
Small torque wrenches are the optimal solution for bikepackers or touring cyclists. Often, bits in various sizes are hidden somewhere in the tool, so you can adjust the handlebars or readjust the saddle while on the go. Their special advantage: They are not only small but usually quite light. So they even fit in a small bike bag or jersey pocket.
A small, lightweight torque wrench easily fits into the pocket on bike tours. Image © Park Tool
The optimal equipment of a torque wrench for bicycles
How many Nm (Newton meters) should a torque wrench for bicycles have?
If you choose a torque wrench that measures 2 to 14 Nm , you have most connections on the bike under control. Perfect would be a tool that measures up to 20 or 25 Nm . Specifically, 1-25 Nm bike torque wrenches are often recommended, with which you can absolutely do nothing wrong!
Attention! There are also torque wrenches whose scale is not indicated in Newton meters . This often occurs with cheap internet bargains. However, since bike parts usually have specifications in Nm, you would have to convert them laboriously, so make sure that your torque wrench calculates in a bike-friendly Nm!
Which bits do you need?
A Torx T25 is the standard on bikes, so a T25 bit should definitely be in your set. Otherwise, Torx heads T10 and T30 are the basics. You should also have hex bits (Allen) available in 2, 2.5, 3, 4, and 6 mm.
What length should a torque wrench for a bicycle have?
The longer the torque wrench, the greater the leverage effect you can achieve with it. If you want to tighten a screw with high torque, a long "lever arm" will help you. For the rather small torques on the bike, shorter tools are sufficient, and an especially long torque wrench would rather get in your way!
Torque wrench for left-hand and right-hand threads
For example, if you want to install new pedals, you will find that one has a left-hand thread and the other a right-hand thread. For this reason, you can set bicycle torque wrenches to "left" and "right."
Quite simply: L stands for left, R for right. Image © Topeak
Do you need a special bicycle torque wrench?
There are manufacturers like Topeak, Birzmann, or Park Tool that specialize in developing tools for bicycles. However, there are also torque wrenches available at hardware stores. So, which is better for your bike? The answer is quite simple: tool sets that are specifically assembled for bicycles usually contain exactly the parts that are used on bicycles. In this case, the appropriate Nm range and the right bits. There are even sets specifically designed for racing bikes, MTBs, or touring bikes. If you specialize exclusively in one type of bicycle, such tools may make sense; otherwise, you can use bicycle tools to get all two-wheelers up and running again!
Cover image © Topeak
