What Is It?
The KCNC Dropout Vertical Extension is a lightweight derailleur hanger adapter that mounts between your bike's derailleur hanger and rear derailleur. Its primary purpose is to position the rear derailleur lower than its original mounting point, increasing clearance between the derailleur guide pulley and large cassette cogs. This allows many drivetrains to accommodate larger cassette ranges without replacing the rear derailleur.
How It Works
The extension bolts directly onto the existing derailleur hanger, and the rear derailleur then attaches to the extension instead of the hanger itself.
By moving the derailleur downward:
- The upper jockey wheel sits farther away from the largest cassette sprocket.
- Shifting into larger cassette cogs becomes possible on drivetrains that would otherwise exceed their maximum cassette capacity.
- Riders can often upgrade to a wider-range cassette for easier climbing gears without purchasing a new derailleur.
Key Features
- CNC-machined aluminum construction
- Lightweight design
- Lowers rear derailleur position for increased cassette clearance
- Compatible with many Shimano, SRAM, and Campagnolo derailleur systems
- Suitable for both road and mountain bikes
- Simple bolt-on installation
- Cost-effective alternative to replacing a derailleur when moving to larger cassette sizes
Specifications
| Specification |
Details |
| Product Type |
Rear derailleur hanger extension |
| Brand |
KCNC |
| Model |
Vertical Dropout Extension |
| Material |
CNC-machined Aluminum |
| Weight |
Approximately 19 g |
| Compatibility |
Shimano, SRAM, Campagnolo |
| Bike Types |
Road, Gravel, MTB |
| Color |
Black |
| Manufacturer Code |
KOT-041-002 |
Who Is This Best Suited For?
Gravel Riders
Ideal for riders wanting lower climbing gears for steep terrain without upgrading the entire drivetrain.
Road Cyclists
Useful when converting a road bike to a wider-range cassette for touring, endurance riding, or hilly routes.
MTB Riders
Can help older mountain bike drivetrains run larger cassettes than originally specified.
Bikepackers & Tourers
A practical solution for carrying heavy loads where easier gearing is beneficial.
Budget-Conscious Upgraders
Perfect for cyclists who want improved climbing capability without purchasing a new rear derailleur or drivetrain.
