Jim’s Tech Talk
By Jim Langley
Availability: This is brand new – Park says it will be in stock soon
How acquired: Sample from the company
Is their less expensive DAG-2.2 still available? Yes. It sells for $79.95
I couldn’t have been more surprised when I opened the box Park’s new derailleur hanger alignment tool arrived in. They had told me a new version of their DAG (Derailleur Hanger Alignment Gauge) was on its way for me to take a look. I assumed it would be a new take on their sturdy, reliable welded-steel chrome plated hanger measurer and fixer. The DAG has been a staple in shops and with home mechanics for decades.
I was flat wrong. Inside the package was a completely new design. Even at first glance it was obvious that Park pulled out all the stops to reinvent the derailleur hanger tool. They ditched the welded steel and went with a one-piece forged aluminum construction. I asked them about this and learned that it’s made like a seatpost because they’re incredibly straight, strong and light.
The forged aluminum comprises the body of the tool, which is also the handle/lever used to wrestle bent hangers back straight. It’s also what all the tool’s other parts attach to. Here, Park did their homework and nailed it again.
Fits More Bikes
The shaft with threads that you screw into the hanger is the smallest diameter (16mm) of any they’ve made on previous DAGs. This allows it to fit into hangers even if they’re tucked under frame pivots and hard to access. Also, the threaded end that’s screwed into the hanger is replaceable should you eventually wear the threads. Just unscrew it with a 5mm hex key and screw in a new one. (The DAG 2.2’s is also replaceable.)
No Play in Any of the Parts
When you screw the tool into a hanger you feel the impressive tolerances of the DAG-3’s movable pieces. There’s absolutely no slop between the shaft and the body of the tool. Should any develop over the years, there’s an adjustment screw to easily remove it.
Play/slop is what makes hanger alignment tools hard to use. It makes it difficult to impossible to get accurate readings. And if you’re not sure your readings are correct, it’s a guessing game trying to straighten hangers. The worst thing you can do, too, is bend the hanger repeatedly trying to fix it.
Looking at another important working part of an alignment tool, the gauge, it too is masterfully designed and executed. It’s made of an injected molded composite. The natural friction reducing nature of the material lets the gauge slide up and down the tool smoothly and again, there’s zero play between parts. The gauge is kept oriented exactly 90 degrees to the wheel because it’s keyed to a groove in the DAG’s aluminum body.
Precision Measurements with Ease
One of the nicest features of the tool is that the pointer of the gauge swings in and out from the tool. This lets you set your measurement at the rim and then swing the pointer out of the way without changing the measurement or risking bumping the pointer and changing it.
Also, being able to swing the pointer out of the way lets you pivot the DAG-3 from 3 to 9 o’clock or 9 to 3 – without hitting the frame stays. The pointer is nicely marked to see exactly how bent or perfectly aligned your hanger is. And the fact that the pointer folds in next to the body of the tool protects it from damage when the tool’s packed in a toolbox.
Overall, I think Park has set the bar higher for derailleur hanger alignment tools with this impressive new model. It’s lighter, easier to use, more accurate, fits more bikes, and has replaceable parts for a long, long hanger-fixing life. Plus, it’s only $37 more than their DAG-2.2.
Also, I appreciate how this tool feels in use. It’s a subtle thing but the aluminum body and composite parts and the tool’s overall lightness seems to me nicer to wield than the all-steel hanger aligners I’ve used for so long.
Here’s my video about the tool so you can see it in use. I talk a bit about how derailleur hangers get bent and quickly demonstrate using the tool. Note that I do not go into great or full detail on fixing hangers.
For full instructions on using Park’s DAG-3, you can read them without even owning the tool here: https://www.parktool.com/assets/doc/product/DAG-3_instructions_2021-03-08-155711.pdf.
Ride total: 9,934
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s streak of consecutive cycling days has reached more than 10,000. Click to read Jim’s full bio.