SRAM Apex Eagle D1 12-Speed Long Cage 52t Max Black Rear Derailleur

The SRAM Apex Eagle D1 is a cable-actuated 12-speed 1x rear derailleur for Eagle cassettes up to 52t. It brings SRAM's mountain-bike clutch and X-HORIZON parallelogram to an entry-level price tier, which makes it a common choice for wide-range gravel builds and budget mountain bike drivetrains.

It mounts to a standard derailleur hanger, works with SRAM 12-speed mechanical Apex and Eagle shifters, and uses an Eagle 12-speed chain. The long cage has a listed 42t chain wrap capacity, sized for a single chainring with a 10–50t or 10–52t cassette.

Who It's For

• Riders building or repairing a 1x 12-speed drivetrain around a 50t or 52t Eagle cassette.
• Gravel and mountain riders who want clutch chain control without electronic shifting.
• Owners of Apex Eagle or mechanical Eagle shifters needing a replacement derailleur.
• Consider a different derailleur if your frame uses the UDH Full Mount T-Type interface, or you run a 2x drivetrain.

What to Look For

• Cassette size: Built for Eagle cassettes with 50t or 52t large cogs; 52t is the listed maximum.
• Shifter pull: SRAM X-Actuation 12-speed mechanical. It will not index with road 12-speed AXS or Shimano shifters.
• Mount: 10x1 standard hanger mount, not T-Type Full Mount.

Key Features

Roller Bearing Clutch. The clutch adds tension to the cage pivot so the chain stays quiet and on the cassette over rough ground, which matters most on a 1x drivetrain with no front derailleur to help.

X-HORIZON parallelogram. Movement is limited to the horizontal plane, which SRAM says prevents ghost shifting and lowers shift force at the lever.

Cage Lock. The cage can be locked forward to take tension off the chain, which makes wheel removal and chain installation simpler.

Long cage, 42t capacity. Enough wrap for a single ring paired with a 10–52t Eagle cassette.

Rider Intent Summary

• Biggest strengths: Clutch, Cage Lock and 52t range at the Apex price tier.
• Tradeoffs: Heavier steel-and-alloy construction than higher Eagle tiers; standard hanger only, so not for T-Type frames.
• What makes it different: An Eagle-range mechanical derailleur that bridges SRAM's road Apex group and its mountain drivetrains.

Victory's Take

We see the Apex Eagle as the practical way to get a 52t cassette on a 1x gravel or trail build. Victory Bicycle Studio can confirm shifter, chain and cassette compatibility before you order.

Specifications

• Brand: SRAM
• Model: Apex Eagle (D1)
• Drivetrain speeds: 12
• Largest cog: 52t
• Chain wrap capacity: 42t
• Cage length: Long
• Mount type: 10x1 standard
• Shifter compatibility: SRAM X-Actuation (12-speed mechanical Apex/Eagle)
• Chain: Eagle 12-speed
• Color: Black
• Part number: 00.7518.178.000