The torque wrench is the universal tool in the bicycle workshop that exudes professionalism – turning the hobby workshop into a semi-professional workshop. But actually, the torque wrench is not a tool per se and it does not replace any other tool in the workshop. How is it that so many bike hobbyists manage without this extra tool? Who really needs the DMS and what function does it perform? Can you also “screw with feeling” – a miracle gift of many supposed master wrenches? We answer all this and more in our guide to torque wrenches – with torque wrench tests and product comparisons.
Torque Wrench Tips And Application
- Torque wrenches are a measuring tool, do not use this to loosen stubborn screws. Otherwise, the spring will adjust and the torque can no longer be set and measured correctly.
- Store the torque wrench at 0Nm so that the spring is not permanently tightened and does not adjust.
- Many manufacturers offer to recalibrate a torque wrench if the wrench has been in use for several years. This allows you to restore accuracy.
- On the bike, carbon parts, and in many other places exact Nm are required. Whether the Nm specification is directly on the part, you can also ask the manufacturer or use our table (for a rough orientation).
Torque Wrench Test 2022
In the first place, two product tables on torque wrench from different manufacturers. Because you can easily distinguish two groups in the bicycle:
- Large Torque Wrenches:
Rather something special on the bike, usually only if you really want to build all the components on the bike itself.
- Small Torque Wrenches:
Mostly the group, which also hobby bicycle mechanics need; And always all who also work on carbon parts.
Precision in torque is important. But you will quickly discover: Almost every bike brand has its own measuring tool in the range. But there are also manufacturers of tools outside the bicycle circle. And these are usually the better tip.
Reliable manufacturers of this precision tool include Proxxon, Hazet, Gedore, Würth, Wera, and KS Tools. Each of these manufacturers tests each individual torque wrench for precision and the test certificate is included in the delivery. After all, precision is what matters when you buy a torque wrench. For this, the torque wrenches of these manufacturers cost a little more and you still have to get a matching bit set (if you do not already have one). But experience reports and tests show: Precision is what counts! If each individual tool is not tested by the manufacturer, you can not rely on the measurement result. The test certificates of these torque wrenches testify to a fluctuation of less than 3 or 4%. With the cheap tools, a fluctuation of 20% or more can already occur. This makes precision work a guessing game.
Special Torque Wrenches For The Bike
Various manufacturers – especially Topeak, Park Tool, or Elite Sports – produce torque wrenches very specifically for use on the bike. These wrenches can usually be adjusted only a little or not at all; they screw every screw to the same torque. On the other hand, these wrenches are cheaper, more compact, and easier to use. And for use on the bike, that’s usually enough.
For example, the Nano TorqBar torque wrench from Topeak: for a relatively low price, it comes with three “TorqBits” (which allows you to adjust the torque: 4Nm, 5 Nm or 6Nm) and 5 screw bits for different screw sizes on the bike.
We have tested the Topeak torque wrench and found: a great tool for on the road. With the included fixed torques of 4, 5, and 6Nm but a manageable range. For all areas of application, it becomes really difficult and a real workshop enriches that not. But just right for all carbon bike parts and for on the road, because at carbon parts exactly these torques are required. The strongest feature is the handiness: all bits can be stowed in the handle. This makes the tool as small as a (thick) ballpoint pen.
Small Torque Wrenches
The small torque wrenches (tool length less than 30cm and torques between 2 and 25 Nm) is suitable for most work on the bike. Here we have written two posts about small torque wrenches:
Large Torque Wrench
The large torque wrench you need only for a few assemblies works on the bike. There are two components that require greater torque: The sprocket set and the bottom bracket. Here you usually need a torque that is between 35 and 70 Nm. However, if in doubt, look again at the component or contact the manufacturer!
When You Need A Lot Of Torque
Especially with safety-relevant components and their screws, a finely adjusted torque is important. With which the screw is secured. Most smaller components need a torque of less than 20Nm. On the following parts, however, it becomes critical if the high torque is not achieved.
These Include Especially:
- Cassettes (at the freewheel)
- Mounting for disc brakes
- Cranks and bottom bracket
- Pedals (yes, in fact, pedals must be tightened to a high torque; the popular belief that pedals tighten themselves is wrong and dangerous; see: Fitting Pedals)
Torques on the Bike – Table
Here is an overview of common torques on various bicycle parts. This table serves only as an overview! Always follow the manufacturer’s specification for the respective component.
We have always also indicated whether you need a large or small torque wrench for the respective bicycle part, and whether the Hazet torque wrench with 10 – 60 Nm is suitable here. We have highlighted this torque wrench because it offers with its torque an intersection between the small and the large torque wrenches. This makes it easier for you to choose the right tool.
Tips – These Bike Parts You Should Screw With The Torque Wrench
- Especially the stem is prone to breakage because the handlebar and stem are exposed to a lot of pressure. In the sporty riding style, the handlebars increasingly bear the weight of the rider. If the bolts on the handlebar clamp or stem clamp are too tight, the bars can break.
- Even with the smaller screws, such as on the shift or brake lever, a screw that is too tight can cause the lever to break off.
- Generally, with all parts and screws made of lighter material, you must pay attention to the correct torque when screwing – so with parts made of carbon or screws made of aluminum.
Proprietary Tools And Universal Tool Holder
Often you can find keys for the bottom bracket or cassette which are integrated (propreitär). In short: the key head and handle are one tool. This is convenient for assembly because you then have everything in one place. But with sensitive torques, it becomes difficult, because you need for the measurement of the torque always a tool with the square drive or at least bits (for small screws).
It is therefore always advisable to order the cassette extractor as a separate head right from the start. And not as an integrated tool. In the best case, you simply have two 3/8″ square wrenches. One is a simple ratchet (for tightening and pulling) and one for measuring the torque.
Who Needs The Torque Wrench?
“Screw by Feel”
Many cyclists and also one or other lazy mechanics think that they can screw with “feeling” without any problems. Those people can be divided into two categories: those with luck (or with components with a high tolerance range), where (yet) nothing has broken on the wheel, and those for whom it will eventually happen. From that point on, they know that the torque wrench fulfills some use on the bike.
Turning By Feel
Often people think that you can equate a lot of force and torque. If I push hard, there’s bound to be a lot of torque. And a skilled mechanic can estimate a torque. This opinion is dangerous because the force=torque equation leaves out an important variable. The lever.
We humans can estimate approximately the force we apply to a key (lever). This works quite well, and as long as we always use the same tool and associate the lever with a force exactly, the torque is also correspondingly the same. But I can apply the same force to a longer/larger wrench and suddenly have a multiple of my previous torque. And that’s where it quickly goes bang.
Engineers who design bicycle components do not choose bolt head sizes arbitrarily. There is a correlation between bolt size and wrench size. With a large hexagonal wrench, more torque is applied (the lever of the hexagonal tools increases with size). That’s why the screw on the stem cap is an M5 (this is where the bearing clearance is adjusted, but no force is applied to it while riding). The stem clamp bolts are then M6 because they expect a higher torque than the stem cap.
Here is a brief list of bolt size and torques as they are quite generally (manufacturer-independent) recommended:
(please note: Manufacturers can always make an even more precise specification for components, eg when it comes to carbon components).
So the size of the lever is very important, at the same time we can feel the force on a lever. But we can never estimate the acting torque correctly! Since we cannot correctly consider the lever in this gut feeling estimation.
Conclusion: You can estimate the torque if you know your tool and do not deviate from it. But if you take a mini tool or use a large 1/2″ ratchet with a small 4mm hex bit then it can quickly crack. And your expensive carbon stem is irreparable for the ton.
Can it be that an average wrench achieves this newton meter figure with his magic arm and fingertip feel? In a way, yes – or at least he gets into the tolerance range. But when hobby wrenches talk about “wrenching by feel,” what they really mean is wrenching hand-tight! Anyone who holds a wrench in his hand can do that. However, the measure of “hand strength” differs according to age, size, gender, stature, and the amount of horsepower in the arm. When someone thinks they “wrench by feel,” 99% of the time they mean they wrench until it’s hand tight, and then that’s fine.
Even Without A Torque Wrench, It’s No Big Deal
But how is it that so many cyclists still manage without a torque wrench? Is hand-tight enough for the screws on the bike – even though it only gives a seemingly subjective measurement?
At this point, we have to contradict ourselves. Because hand-tight is often sufficient! The manufacturers do in fact give some thought when they use different-sized screws on their components. This is not a marketing trick to sell different-sized screwdrivers. In fact, screw size is related to the lever arm of the screwdriver. A larger screw requires a larger screwdriver with a longer lever arm, which naturally results in a certain Nm span regardless of the mechanic’s arm. However, this is only a span width or a tolerance range! This tolerance range is sufficient for everyday screw work on a normal bicycle. For screws or components made of lighter materials, such as aluminum screws or carbon parts, or on the other hand for bicycles that have to withstand a lot (MTB!), more precise work is required. This precision is achieved – even after practical experience with torque wrenches – only with the torque wrench!
In an emergency, a skilled mechanic arm can screw the component on the road without a strain gauge, but this is always only an emergency solution. In the long run, incorrectly screwed components represent a safety risk – no matter how “sensitively” you proceed when screwing.
Torque Wrench Function And Setting
So what function does the torque wrench perform on the bike? Whether road bike or MTB – the torque wrench fulfills an essential function as the mechanic’s best friend. With the torque wrench, a screw can be set to a preset torque. This means that the screw is not too loose and also not too tight – both of which lead to serious errors that endanger the safety of the driver. So with that, the torque wrench is more like a measuring device. You also still need the appropriate tool in any case, which you would otherwise use, and use it for the actual screwing.
Under no circumstances should the torque wrench be used to loosen screws! If too much force is applied, the internal mechanics of the strain gauge can be damaged.
How Does A Torque Wrench Work?
The torque wrench allows you to tighten a screw with an exact torque that you set on the wrench beforehand. The torque represents a certain amount of force with which you tighten the screw, and it is expressed in Newton-meters (Nm). This is because the torque is calculated by the length of the lever arm and the force with which you operate the lever arm.
So what is the operation of the torque wrench? It measures the torque of the screw on which you put it. First, you should tighten the screw with an ordinary wrench until the screw is almost hand-tight. Then you tighten again with the torque wrench until the wrench gives a signal – this varies from wrench to wrench. Most torque wrenches give a loud crack, other wrenches then also buckle so that you do not accidentally continue screwing. In any case, the signal means that the desired torque has now been reached and you no longer need to continue screwing.
Many hobby screwdrivers then turn even further to let it crack one or two more times! It is really puzzling – maybe you want to play it safe, or you just want to let it crack again. With this, the torque is falsified. After all, the signal comes for a good reason at a certain torque. If you continue screwing anyway, you can also use a normal wrench. Just let it crack once and that’s it!
How Do You Set A Torque Wrench?
The most important thing: You need to know which torque you need for the respective screw in the first place. Some bike parts are labeled with an indicator of how many Newton meters (Nm) you should bolt the part too. The torque wrench display is also in Newton meters. The strain gauge may have a mechanism for fixing the torque, which must first be loosened (a lock ring, for example, which you have to unscrew by hand). Then you should be able to turn the handle, which should change the torque indicated by the wrench. The torque reading is completely different from wrench to wrench! If in doubt, read the instructions or contact the manufacturer of the tool.
The most important thing: Set the torque wrench back to “zero” after work is done! If the torque wrench remains tightened for days or months, it loses clamping force and the torque is distorted. Otherwise, there is not much to consider when setting the torque wrench!
Checking The Calibration Of The Torque Wrench
In the following article, I show you how you can check with simple means whether a measuring tool for torque is actually set correctly. In addition, you can check every year whether your own measuring tool is still good.
Digital Torque Wrench
Furthermore, digital torque wrenches can also be found, which have a somewhat different mode of operation than mechanical torque wrenches. In principle, however, they differ from ordinary, “analog” torque wrenches mainly by the digital display. Setting the desired torque is so much more convenient.
The price range here shows an extremely high fluctuation. So you can find digital torque wrenches (or even better: “electronic torque adapters”) from about 100€, but the digital strain gauges of the well-known manufacturers you get only from about 1,500€. We implore: Don’t be tempted by the digital display! Decent digital torque wrenches are unfortunately so expensive because the inner mechanics are much more complex than in mechanical torque wrenches. Ordinary torque wrenches have a spring inside that is tensioned when the torque wrench is adjusted. Digital torque wrenches have a compression coil inside. This is much more complex and expensive to manufacture.
In return, digital strain gauges (when individually tested!) are extremely accurate and usually have less than 1% variation. So they can be true luxury torque wrenches. But as with mechanical wrenches, the same applies here: With cheap wrenches, the torque fluctuates so much that setting it is a complete guessing game. Therefore: wherever no individual test certificate is enclosed, you cannot rely on the measurement result of the wrench. With the cheaper torque wrenches, no individual test takes place (“cheap” means here actually: less than 1,000€). It is here, more or less, electronic garbage. Because for the same money you get a decent mechanical torque wrench that actually achieves the desired torque.
Digital torque wrenches only make sense if you are willing to spend over 1,000€ for a tool. But you get something for your money: a tool that works extremely precisely and is easy to adjust.
Torque Wrench Supplier
Here is an overview of well-known manufacturers of torque wrenches. These are German manufacturers of tools and assembly parts whose products are sold worldwide. For all of the manufacturers listed here, each torque wrench sold is individually tested and the test certificate is always included. This is necessary to ensure the precision of the tool.
Proxxon Torque Wrench
Still a fairly unknown name in the bicycle trade, Proxxon is more in the field of fine electric tools. The company is headquartered in Luxembourg, but Proxxon, as an international group, is also on the ground in Germany and America.
The torque wrenches from Proxxon stand out due to the price, which is far below the competition. Unfortunately, it is therefore natural to classify Proxxon wrenches in the category of cheap tools. This is a mistake! Every single torque wrench from Proxxon is tested for accuracy, just like the torque wrenches from other well-known manufacturers, and it also comes with a test certificate. Meanwhile, the Proxxon torque wrenches have already caught the eye of some testers, which is why they are just gaining popularity.
Hazet Torque Wrench
Hazet is one of the leading German tool manufacturers with now 150 years of company history. Hazet is a name to build on, and that’s why Hazet torque wrenches are also in high demand for bikes, cars, and industry.
Wera Torque Wrench
Wera’s tools are most notable for their chic design, which consistently earns the German company awards. However, Wera tools are not inferior to the tools of the major international companies listed here in terms of functionality and precision. While we’re dealing with a relatively small company here, they specialize in the manufacture of screw driving tools and they offer all the services you could ever want for their tools. Again, you’re in good hands when you buy a Wera torque wrench.
KS Tools Torque Wrench
At only around 25 years old, KS Tools is the youngest of the manufacturers listed here, but despite this, the German company is already enjoying great success. As the name suggests, the company specializes in tools and therefore you can also trust the quality of KS Tools torque wrenches.
Torque Wrench – Which Brand?
When it comes to torque wrenches, there are several well-known manufacturers of tools and components that you can rely on. Many of them are based in Germany or Luxembourg and sell their products on an international level.
What is Cheap Torque Wrenches Well For?
Cheap torque wrenches that cost under 50€ or come with a matching bit set are not subject to individual testing. When you use such a torque wrench, the actual torque can deviate by 20% or more from the desired torque. That means those cheap torque wrenches are not very good. After all, this is a precision tool and precision requires accurate, time-consuming work. Torque wrenches from reputable tool manufacturers are all individually tested and the customer is supplied with the test certificate.
Torque Wrench: How Often to Crack?
Once. The crack tells the screwdriver that the desired torque has been reached. If you continue to turn, you falsify the torque.
How Often do Torque Wrenches Need to be Calibrated?
Frequent use wears out the mechanics of the torque wrench. Thus, the desired precision deteriorates with the ravages of time. To repair the torque wrench, you can have it calibrated by the manufacturer. Or you can go to a test center like Dekra and have it done there. In both cases, you may pay: Depending on the manufacturer or the test center, calibration costs about 50€. However, this should be a rare matter for private customers. For those who use the torque wrench commercially and are liable for their work, every torque wrench should be calibrated at least once a year. But even without intensive use, the precision mechanics of the torque wrench will age over time. Hobby wrenches should have the torque wrench recalibrated after three years at the latest.
Which Torque Wrench for the Bicycle?
In principle, the same torque wrenches are suitable for a bicycle that is used elsewhere. However, it is important – as with all other uses of the torque wrench – that the wrench is built for the appropriate torque. Every torque wrench, no matter how expensive or high quality it is can only manage a certain range of torques. So, of course, much higher torques are required on a car than on a bicycle. For most work on the bike, you need a torque wrench that creates between 2 and 15 Nm – but for certain parts (sprocket set, bottom bracket) you need a torque that is between 30 and 70 Nm. Thus, you need two different-sized torque wrenches to perform all assembly work on the bike. Mostly, however, a small torque wrench is enough!
Which Torque Wrenches are Available?
As with all tools, the same applies here: There are cheap and expensive ones. But even more than with other tools, you should stay away from Aldi and Lidl tools! After all, precision is what counts when it comes to strain gages. Cheap tools are not subject to individual testing and accuracy is therefore not guaranteed. The torque wrenches of reliable manufacturers (Proxxon, Würth, Hazet, etc) are always supplied with the test certificate of the individual tool, which testifies to a measurement variation of less than 3 or 4%.