The job
A rotating/sliding indicator and replaceable M10 tip; not a general frame-alignment gauge.
Park Tool · Derailleur-hanger alignment gauge
Park Tool DAG-3 Derailleur Hanger Alignment Gauge
A rotating/sliding indicator and replaceable M10 tip; not a general frame-alignment gauge.
$148.95Nov 7, 26, 12:59 AM · New York
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- Reference Rim-referenced hanger alignment
- Indicator Rotates/slides for clearance
- Maker wheel scope 16–29 in+ /ISO-ETRTO317–630+
Reference
Rim-referenced hanger alignment
Identify which alignment is being checked
Hanger alignment and dropout parallelism use different references and receiving points.
What this choice changes
A rim-referenced check for the derailleur hanger
The DAG-3 checks the derailleur hanger against a rim reference. Its indicator slides and rotates to clear obstructions, while the threaded tip locates the tool at the hanger. This is useful when the hanger relationship is the question to investigate; it is a different measurement from checking whether the frame or fork dropouts are parallel.
Park Tool specifies wheel sizes from 16 to 29inches and larger, identified as ISO/ETRTO317–630+, and names low-clearance thru-axle and Shimano Direct Mount hanger applications. These examples do not establish fit for every hanger. The tip is M10, but no pitch is supplied here as an assumed universal standard.
The extruded-aluminum body has a maker-listed 420 mm length. Compare the actual hanger interface, access and rim reference before buying. Detecting a deviation does not establish that the hanger or frame material may be bent; the component’s service requirements determine the permitted response. A replacement threaded tip is separately listed rather than an extra supplied part.
Specifications & supplied details
| Detail | Specification |
|---|---|
| Model | DAG-3 |
| Reference | Rim-referenced hanger alignment |
| Tip | Replaceable M10; pitch not established here |
| Indicator | Rotates/slides for clearance |
| Maker wheel scope | 16–29 in+ /ISO-ETRTO317–630+ |
| Maker body/length | Extruded aluminum /420 mm |
| Supplied | One gauge; no spare tip or bicycle parts |
Choose for your actual setup
Identify which alignment is being checked
Hanger alignment and dropout parallelism use different references and receiving points.
Verify hanger access
Match the actual hanger interface and wheel/rim reference, not just a named bicycle category.
Fit checks & limits
- No universal hanger fit or permission to bend every hanger material.
- Selected mass 2.1 lb differs from maker 645 g; no single carrying weight is asserted.
Questions before you choose
Does this check frame-dropout parallelism?
Its reference is the derailleur hanger relative to the rim. FFG-2 serves the separate dropout-parallelism check.
Is the M10 tip supplied as a spare?
The tool has its working tip; an additional replacement tip is not established as supplied.
Does a detected deviation mean I should bend the hanger?
No. Identify the exact component’s permitted service response; measurement does not establish material repairability.
Guides for this choice
Other equipment to consider
Selected listing details, manufacturer information and source images were compared. No hands-on trial or universal fit is claimed. Product identifier: B08Y6786WF.