Hanging gauges that were once considered only for workshop use are now a common tool for perfect gear shifting.

The rear derailleur stretched out in the wind, controlled the rear gear and waited to bend, the rear derailleur was in an unstable position. Therefore, the small hanger on which the derailleur is usually fixed is designed as a weak point. It is better to destroy a replaceable aluminum sheet than to destroy an expensive derailleur, or worse, to destroy the frame.

But because the transmission pylons are designed for sacrifice, it also means they are easy to bend. This manifests itself as cunning and inconsistent shifting, which is a problem that cannot be solved by any cable tension adjustment, limit screw manipulation, or chain cleaning. The derailleur hanger alignment gauge tool is not only very useful for diagnosing whether your hanger is actually bent, but it can also make it straight again.

In the updated version of this feature first released in 2016, we investigated, reviewed and compared the best choice for the transmission hanger alignment gauge tool.

The hanger tool was previously considered a store-only item, especially because it only needs to be used occasionally. However, as the distance between the flywheels becomes smaller and the frame becomes lighter, such tools become more necessary.

In fact, I used to work in a store where the policy was to check every new bike sold, as well as any quality bikes that were being repaired. To be honest, about one-third of new bicycles will have hanger alignment problems right out of the box, which are then carefully corrected. Similarly, the hanger alignment can be affected by simple things, such as improper transportation of a bicycle in a car, or being bumped while waiting for a rider in a cafe.

The derailleur hanger gauges may look complicated, but their functions are very simple. Generally, a tool thread replaces the rear derailleur to provide a pivoting gauge for measuring the distance between the tool arm and the rear wheel rim.

As long as the derailleur hanger is tight, the wheels are real, and the hub axle is straight, the hanger tool can effectively measure the parallelism between the derailleur hanger and the rear hub axle. When the meter is equidistant from the rim at six, nine and twelve o'clock positions, the hangers are perfectly aligned.

Therefore, using the hanger alignment tool only needs to align the gauge with the rim at the 6 o'clock position, and then swing it to the 12 o'clock position. If the gauge is not aligned with the rim, the hanger is bent. The tool arm provides enough leverage to gently "convince" the hanger to realign. Once the 6 o'clock position is aligned with the 12 o'clock position, check the 9 o'clock position and bend as necessary until the three positions are evenly aligned with each other, as shown below.

Both Park Tool and Shimano stated that a change of up to 4 mm on the rim (equivalent to a deviation of approximately 0.75° from the true) is acceptable for normal operation. Others, such as Jason Quade of Abbey Bike Tools, say that the top-level drivetrain can benefit from more accuracy.

There are some common things you need to pay attention to when using hanger tools. First, always make sure that the rear wheel fits perfectly in the hook and is tight. Make sure the hanger itself is tight. If your wheel is not exactly right, then just use the valve lever as a consistent reference point and use the calibration gauge of the derailleur hanger tool to rotate it.

You can use the hanger tool to gently bend the hanger. As long as the hanger is still in good condition and connected in a way that will not damage the frame, I am usually happy to do so. Be very careful not to overemphasize the material you are using. Aluminum hardens when it is repeatedly bent, which means that the more you fiddle with it, the more brittle it becomes. If the hanger requires more than just the gentlest adjustment, you might better replace it completely-if the stock drill bit is noticeably soft, it is better to use a high-quality machining unit (from a third party, if necessary).

Also pay attention to the frame material. Some people recommend and least recommend the use of hook tools with certain carbon fiber frames. If in doubt, consult the frame manufacturer.

Perhaps the most important aspect of any centering tool is its accuracy, and for hanger tools, the difference between the cheapest and most expensive tools is usually obvious due to the amount of lateral play at the tool pivot point. The cheapest hanger tools tend to swing, making it more difficult to accurately measure the alignment of the hanger. Keep in mind that your goal is to be within 4 mm for sufficient movement, so even a small amount of lateral play at the pivot point will become quite exaggerated at the other end and will undermine the accuracy of the tool.

Frame clearance is another important aspect to consider, especially if the bicycle you are processing is equipped with a frame or fender. Here, the indicator rod of the tool needs to bypass these obstacles without losing the settings. Some tools (such as Park Tool DAG-2.2) do this by simply using O-rings to mark the position, while other tools (such as Abbey HAG) can rotate around such obstacles for faster and more accurate use.

Modern bicycles with cylindrical axles can also challenge the practicability of old hanger tools, and the new design helps overcome such gap problems. The HAG from Abbey Bike Tools may be the first to solve this problem. It has a longer and narrower tip that can remove almost all falling devices, while all other brands tested here have adopted similar solutions (please See the example in the gallery below). I think open compatibility is a key feature, so tools that are outdated in this area are excluded from this test (such as Cyclo and Cyclus).

It is very encouraging that compared to the tools tested in 2016, the new version of the tool tested here shows that the tool manufacturer is very aware of the importance of the above elements. For example, Park Tool and Lifeline have greatly improved the accuracy and compatibility of their respective tools.

If you plan to use a gear bike with smaller wheels (such as a folding bike or a gear kids bike), then you may need to pay attention to the minimum usable length (listed at the bottom of this article). For example, a 20-inch wheeled bicycle requires a tool with a minimum usable length as low as about 200 mm, so Abbey HAG and ZTTO HAG cannot be used in this case.

It is also worth noting that such smaller-wheeled bicycles usually have only 6-7 gears, so the "close enough" hanger alignment can usually be done with the naked eye without the need for special tools. It is mainly the newer 10, 11, 12 and 13 speed transmission systems that require precise hanger alignment.

There are other issues with the derailleur hook tool that need to be considered. Ease of use is always something to keep in mind. If you plan to carry tools with you, pay attention to the size and weight of the tools.

If you don’t use any tools, it’s difficult to judge its accuracy and practicality, so I collected what I think is the best and most popular hanger tool to meet the different needs (and budgets) of families and professional mechanics. This includes tools from Lifeline, Park Tool, Abbey, Unior, ZTTO, Shimano and Wolf Tooth.

It is worth noting that there are many other hanger tools on the market, including DIY and low-cost copy options. As mentioned earlier, many of the cheaper options suffer from excessive bolt clearance (such as some imitations of Park Tool) or due to low bolt clearance (such as the reasonably priced Cyclus and Cyclo hook tools, or the simplest eBay option). At the same time, there are definitely DIY options that can correctly perform the task of straightening the derailleur hanger, but many of them rely on skilled creation.

By applying consistent pressure on the tools in use, you can carefully reduce the free gaps in many of these tools, but in reality, using tools that provide tighter tolerances and less swing, you will always achieve higher accuracy—and Such tools also happen to be easier to use. At the same time, there are no great or simple techniques to overcome the lack of tools suitable for the new style of dropout permission.

The hanger tools are listed below in order of my preference (favorite to least favorite).

Abbey Bike Tools, headquartered in Bend, Oregon, manufactures a limited range of bicycle tools that are usually found in the toolboxes of many WorldTour mechanics and ToolBoxWars enthusiasts. Among all the tools tested, HAG is my favorite tool. Of course, such quality comes at a price.

This telescopic tool provides an easy-to-lock indicator rod that can rotate freely. The result is that no matter what kind of bicycle is used, tools can be used quickly. Of all the tools tested, it is the most obvious tool with tolerances, which can eliminate all detectable movement. In return, you have absolute confidence in the alignment of the measurement.

It is designed for daily workshop use, but its compact size and light weight make it the first choice for storage in portable toolboxes, tool rolls, or places with limited space. Since I first purchased my Abbey HAG about seven years ago (it still looks like new), Abbey has subtly adjusted this tool. The latest production version has stricter manufacturing tolerances than before. If it is fixed on an unattended bicycle, it can prevent the body from falling under its own weight. The head is chamfered to remove the most demanding (worst) frame parts. Now, from an aesthetic point of view, it is fully in line with the asking price.

Yes, this tool will exceed the budget of many people, but excluding Shimano, it is clearly better than other tests. If you value quality products that can last a lifetime, then this is the product you want. Please note that it does not apply to wheel sizes smaller than 24 inches.

Advantages: accurate, easy to use, compact, durable, spare parts available. Low point: The price is too long to accommodate small-wheeled bicycles. Price: 185 US dollars / 185 euros / 317 Australian dollars Manufacturer page: abbeybiketools.com

It can be said that there is no hook tool that is more commonly owned and used (and copied) than Park Tool's DAG series. In recent decades, the dimensions of the tool have not changed, but Park has steadily improved the operating tolerance and differential pressure compatibility. The most recent update is DAG-2.2.

This tool will continue to do everything it needs to do without making a fuss. The somewhat agricultural building is sturdy and reliable, and of course you dare to bend any dropouts. 

It is worth noting that it does not have a quick pivot or similar function for fixing the indicator rod. Its head also has some measurable movement (1.1 mm), and it is not that friendly to store in a portable or compact toolbox. Nonetheless, it is a safe purchase for many people, and my recommendation for those who need reliable workshop tools and cannot prove something like Abbey HAG.

The last thing to note is that Park Tool provides reliable warranty and repair parts support for old products. I personally think this justifies the higher asking price than the cheaper copy version. 

High point: price, simple structure, fairly easy to use, availability of spare parts. Low point: does not rotate around obstacles, average accuracy, not compact. Price: 80 USD/80 Euro/150 AUD (usually found at a lower price) Manufacturer page: parktool.com

Lifeline is Wiggle/CRC's own brand, and many of the company's tools often use other names. In this case, the Lifeline Hanger tool is almost the same as the SuperB hanger tool (and possibly the manufacturer).

I am very happy to be able to use the latest version of this tool and see its development progress since I last reviewed it in 2016. The new version is no longer restricted by hanger compatibility, and the tolerance has been greatly improved. 

In general, the functions (and limitations) of this tool are very similar to Park Tool DAG-2.2, although the measurable movement of the head (1.5 mm) is slightly more, which affects its absolute accuracy. Similarly, although the indicator rod is very safe in use, it is not physically locked, so accidentally hitting it on the rim or tire will require you to recalibrate.

Nevertheless, for many home mechanics, this tool (or SuperB equivalent) is still an affordable and fully adequate option, and it is what I recommend to those who can't stretch with Park Tool DAG-2.2. Note that repair parts for this tool are unlikely to be available for a long time, and the park has clearly defeated this.

High point: price, simple structure, fairly easy to use, availability of spare parts. Disadvantages: no rotation, average accuracy, not compact. Price: 67 USD/48 EUR/93 AUD (usually purchased at a lower price) Manufacturer page: wiggle.com

Shimano TL-RD11 is rare, but its features are quite outstanding. The design is very similar to the Abbey HAG, but the Shimano tool adopts a keyed telescopic design and a pivoting indicator rod, which is locked to a consistent square position by a stop ball. This clever rotating indicator design is licensed by Efficient Velo Tools.

The indicator rod is actually a small steel ruler. Although it is not locked in place, it is firmly fixed to ensure that you do not accidentally change its position. However, you need to be careful not to scratch the rim with it.

Overall, the tool is an impressive combination of robust construction, compact size and ease of use. Please keep in mind that the sample I tested had a hard life before my experiment, unfortunately, it still showed some obvious performance (this is not the case with my 7-year-old Abbey). One thing to add is that the tool is not as compact as the similarly priced Abbey, and it is easy to store or purchase replacement parts. My choice of the overall best option is still green.

I would love to own one of them, but only if the price is significantly better than Abbey HAG.

Advantages: easy to use, fairly accurate, and durable. Low point: the price, a small amount of disassembly is required for compact storage, and the worn samples show some drama. Price: 300 USD/200 Euro/310 Australian Dollar Manufacturer Page: Not Applicable

As a new member of Park Tool's extensive series, DAG-3 is designed as an advanced version of the widely used DAG-2.2. The expected benefits of this tool include significantly improved build quality, smoother operation, and an indicator rod that can rotate around the fender and frame tube. When measuring the performance of the tools, DAG-3 followed Abbey Bike Tools.

In general, this new hanger tool works well, but I personally did not accept the new indicator bar design that uses a small wave spring to hold it in place. Here, the tool cannot lock the indicator bar setting in place. I often find that I accidentally touch the indicator bar to the wheel rim and then lose my starting position. As a result, I had to start the alignment process again.

The Lifeline Pro hanger tool exhibited the same problem, but Park DAG-3 was worse because of the lower spring tension. If Park adds the ability to lock the indicator rod, this will be a very good choice.

Advantages: precise rotation design, availability of spare parts, handle end caps can be replaced with any Schrader valve caps (interesting). Disadvantages: The indicator rod cannot be locked, which makes the tool more troublesome to use and not compact. Price: 117 USD / EUR to be determined / 200 AUD Manufacturer page: parktool.com

Search for bicycle parts, tools or accessories on AliExpress, eBay or Amazon. You will most likely see ZTTO on the first page of search results. This low-cost hanger tool is obviously inspired by Abbey HAG, but its design is actually significantly different (worse). 

Tools mainly made of aluminum provide a keyed telescopic design, and a detachable indicator rod can be rotated freely at the end of the tool. The tool is very light and cheap, but it has some considerable design flaws. For example, although the head is quite free, the keyed telescopic design is not. Once it reaches the 700C/29er rim, the playing effect will be significantly worse.

Likewise, the indicator rod cannot be locked in place, but instead relies on the O-ring to maintain the measurement. Before using this measurement to make any bends, you definitely want to triple-check the measurement. Similar to Abbey HAG, the minimum usable length of the tool means that it is not suitable for small-wheeled bicycles.

The pricing of this Abbey look is undoubtedly attractive, but before I recommend this tool to anyone, the indicator rod needs to be secured more securely. A skilled manufacturer will be able to drill/tap screws to solve this problem, but you don't need to modify the newly purchased product to make it work properly.

Advantages: price, portability, rotating design. Low point: accuracy, indicator rod is loose and cannot be locked, spare parts are available, not suitable for small-wheeled bicycles. Price: 52 USD/49 EUR/75 AUD Manufacturer page: AliExpress.com

Unior Hanger Genie only appeared a few years after Abbey HAG and clearly showed some similarities. The tool is very compact, it provides an indicator rod that can either be locked in its setting, can also be rotated around obstacles, and can withstand percussive sounds.

Sadly, in use, Unior feels like a less refined version of Abbey HAG. Compared with any other tool in the test, my sample has the largest amount of head movement (cannot be adjusted), so it lacks confident accuracy. At the same time, the sliding surface is not so smooth, and the steel structure is prone to surface corrosion.

In addition to these problems, Unior's limited telescopic range means that the tool has a second offset indicator rod that can be used with very small or large wheels. To be honest, this is a supplement, just an afterthought.

Unior manufactures many professional-quality tools, but unfortunately, this tool is insufficient. This tool still has many things to like, but fundamentally speaking, the price is too high given that the tolerance does not allow the accuracy of the datum alignment.  

Advantages: small size, easy to use, rotating design, indicating rod can be locked in place. Disadvantages: Poor tolerance will affect accuracy, susceptible to corrosion, and expensive. Price: 130 USD/90 EUR/220 AUD Manufacturer page: uniortools.com

Wolf Tooth's hanger alignment method is unique. This hook tool is durable, lightweight and packable. It is part of Wolf Tooth's ingenious packaging tool series. Unlike all other tools described above, this hanger tool does not use the rim as a reference point for perpendicularity, but uses two parallel rods on the shaft. 

Our previous report on this unique hook tool demonstrated its function: You insert a large rod into the position of the rear derailleur, and then replace the barrel shaft (or the end cap of the quick-release fork) with a second rod. Wolf Tooth offers accessories for the three most common barrel thread pitches, and the tool is impressively packaged in a very compact and high-quality component. 

Functionally, the tool solves common problems, such as concerns about the straightness of axles or rims, compatibility with large and small wheels, and it will not be affected by the measurement swing. But this design introduces other problems, such as the need for a keen eye to get the perfect straightness of the hanger, if you need to adjust between multiple bicycles, the use speed may be slower, and then in some closed rear fork designs Can’t be used at all (for example, many Canyon bikes and the new BMC SLR01). Those who are interested in the simplicity of design should also check out this DIY version.

I really question the low ranking of this tool in this test, especially considering how well it is made. Perhaps straightening the derailleur hanger in one way for the past two decades has led to my prejudice on how to best accomplish this task. I personally find this tool slower and harder to use, but those who approach this task with a fresh perspective may have different opinions.

Advantages: fascinating design, lowest weight, no gaps or wheel issues to prevent alignment, availability of spare parts. Low point: It is more laborious to set up and requires careful observation of accuracy. It is not suitable for some frames with closed ends or strange shaft thread pitches. Price: 120 USD / 125 EUR / 190 AUD Manufacturer page: wolftoothcomponents.com

As the brother of the Tune Spurtreu stem alignment tool, this laser-based tool is not a hanger alignment tool, but a tool designed to help align the derailleur limit and cable (or electronic) tension. It works by inserting the tool bit into the derailleur and aiming the laser straight at the chain on the flywheel-from there (at least in theory), the laser should show you where the center of the derailleur pulley should be located.

It is true that I bought this tool in the hope that it can quickly diagnose a curved derailleur/hanger, but it does not work well. Likewise, it is definitely not intended to be used to bend a curved derailleur back to parallel. Therefore, although it is not really part of this test, I think I will include it just in case you consider buying it through the above options.

Even if it is used for its intended purpose, it has some major problems. Just insert the hex wrench into the mounting bolt of the rear derailleur, and there may be some wobble in the tool interface-now suppose you install a laser on the other end of the hex wrench and it is wiggling at the same time-not completely accurate, is it?

I also found that the dial-in tool is much more time-consuming than adjusting the derailleur by ear or eyes. And on multiple derailleurs, I couldn't get a tool suitable for short drill bits in its inventory. Then you need to deal with tiny precision screws to solve this problem. I can continue, but I have used too many words on the tool and it cannot help you correctly diagnose a bent hanger or repair a hanger. 

It is undeniable that this thing is impressive, with its lush green anodized treatment on complex machining tools. Who doesn't like lasers? But I don't like this tool at all, and wholeheartedly cannot recommend anyone to buy one (unless you want to buy mine. Just kidding. But neither).

Advantages: Working with the derailleur in place, the laser is cool. Disadvantages: It is almost useless for diagnosing the alignment of the hanger. It depends on the tolerance of the transmission bolts. It is delicate and cumbersome to use. Price: 200 USD / 130 EUR / 250 AUD Manufacturer page: tune.de

Although I support the above options of home users and professional mechanics, there are other better-quality options. The most noteworthy one comes from EVT, it can be said to be the best, as long as the cost, weight, cost, storage space and cost are irrelevant. Did I mention that it is $600 and has a limited supply?

At the same time, many experienced mechanics will swear by the classic Campagnolo hook tool. Although I cannot deny its functionality on classic road bikes, it does lack the extensive bike/frame compatibility and accuracy in the latest test tools. It is for these reasons that it was omitted in this shootout; so are the affordable tools of Cyclo and Cyclus.

Is there a good hanger tool? How about a DIY hacker who does the job? Please let us know in the comments below.