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 together. A torque wrench with various attachments is also part of the basic equipment if you don't want to damage your bike during simple adjustments. Depending on the type of bicycle and equipment, a bicycle has around 40 screw connections, 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 used for screw connections, but today exact numbers are the norm, and the torque wrench measures them.
Why does your bike 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 in front of you), there are numerous screw connections. You can tighten the screws by feel here. 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 deeper, the handlebar can be turned, or the luggage rack doesn't hold. And if you tighten too much ... well. Then it goes "crack" and something is broken. There are two possible horror scenarios here. Either the screw eye breaks. Over-tightened bicycle parts can also damage the part that is supposed to be clamped. For example, an over-tightened stem can cause a carbon handlebar to crack. Similarly, this can happen with the seat post.
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This is why screw connections on bicycle frames and components often have an indication engraved that tells you how tight you can tighten a screw. This applies to both the clamping and the part that is to be clamped! |
You should adhere as closely as possible to the specified torque when assembling new bicycle parts. Image © Reverse
A torque wrench helps you to precisely maintain the specified force. This creates reliable connections, but nothing breaks either.
Here are some bicycle parts that should be fastened with a torque wrench:
- any 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's 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 bicycle screws, this 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 often find it in connection with torque wrenches and bicycles.
- Torque is measured in Newton meters (short: Nm).
Incidentally, you will find another specification 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: The drive of a simple city e-bike has about 40 to 50 Nm of torque, an eMTB can have 85Nm and more. A screw on the stem is usually tightened with 3 to 6 Nm.
Torque wrench on carbon bicycle or for carbon components
For a carbon bicycle, 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 are somewhat sensitive to localized stress, they can break more easily than parts made of aluminum or steel. For this reason, screw connections are particularly delicate here, and you should always work with a torque wrench !
In addition to the torque wrench, you should always have a tube of carbon paste in your toolbox for your carbon bicycle. The connection between the bicycle parts can be significantly improved even with little tightening force. Everything you need to know about carbon assembly paste can be found 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.
Using the twist grip, you set the desired Nm. Image © Topeak
Many torque wrenches work like a ratchet or socket wrench, they tighten screws in one direction, and in the other direction, they "spin freely." You can set the torque wrench to "left" or "right" (= engages clockwise or counterclockwise). This is important, for example, when installing pedals.
How to use the torque wrench correctly on the bicycle:
- Find the allowed tightening torque on the bicycle part you want to assemble
- Set the Nm on the torque wrench
- Set it to the desired rotation direction, left or right
- Insert the appropriate bit
- First insert the screw by hand and tighten it slightly with your fingers, you will notice if it is cross-threaded
- When the screw is properly seated in the thread, you can tighten it on the bicycle with the torque wrench
- When the required torque is reached, the torque wrench clicks, or it "snaps" as you turn it
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The golden rule of the torque wrench: When the allowed (or desired or set) torque is reached, and the torque wrench snaps, you should STOP pulling immediately! |
To relieve the spring inside the torque wrench, you need to set it to "zero" while it waits in the toolbox for its next use.
What torque wrenches are available for bicycle work?
Simple, inexpensive torque wrenches
There are very simple and very inexpensive torque wrenches that at least give an indication of how tight you have tightened a screw. They are not recommended for carbon parts!
This torque wrench is "very basic," but it does what it's supposed to! Image © Topeak
Digital torque wrenches
On a torque wrench with a digital display, you can set the torque particularly easily and accurately. Their disadvantage is obvious: You need batteries!
The luxury version for true bicycle enthusiasts: The torque wrench with digital display. Image © Topeak
The "normal" torque wrench for bicycles
Mechanical torque wrenches are widespread and they don't cost the earth. 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 work on bicycles! Image © Park Tool
The mega set for all eventualities
A lot of bits are one thing. Extensions (i.e., bit holders with handles) 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 cyclists, this set may be oversized. However, anyone who likes to work on their bike themselves will find everything they need here! Image © Topeak
Compact torque wrenches for on the go
Small torque wrenches are the optimal solution for bikepackers or touring cyclists. Often, bits of 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 the bicycle
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. A tool that measures up to 20 or 25 Nm would be perfect. Specifically for bicycle torque wrenches 1-25 Nm are often recommended, you can't go wrong with that!
Attention! There are also torque wrenches whose scale is not indicated in Newton meters . This often occurs with cheap internet bargains. However, since bicycle parts generally have specifications in Nm, you would have to convert them laboriously, so make sure your torque wrench calculates in a bike-friendly way in Nm!
Which bits do you need?
A Torx T25 is the measure of all things on a bicycle, so a T25 bit should definitely be included in your set. Otherwise, Torx heads T10 and T30 are the basics. Additionally, you should 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 you can achieve with it. If you want to tighten a screw with a high torque, a longer "lever arm" will help you. For the rather small torques on the bicycle, shorter tools are sufficient, a particularly long torque wrench would rather be in your way!
Torque wrench for left-hand and right-hand threads
For example, if you want to mount 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, who specialize in developing tools for bicycles. However, you can also find torque wrenches in hardware stores. So, what is better for your bike? The answer is quite simple: tool sets that are specially put together for bicycles usually contain exactly the parts that are used on the bicycle. In this case, the corresponding Nm range and the appropriate 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 might make sense, otherwise, you can use bicycle tools to get all two-wheelers up and running again!
Cover image © Topeak
