The PDX TI ROCKERBONE is designed to work with Rocker-style dropouts only. 
The ROCKERBONE provides a simple and precise means of tensioning Rocker-style dropouts with two tool options:
- standard 19mm open end wrenches in the shop
- standard 8mm hex wrenches on the go

Ideal for use with Gates Carbon Drive belt systems. Works with chains, too!
Sold as a set of 2. Includes TUFFBOLTZ and washers.

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Precision cast from aerospace grade aluminum, finish machined to precise tolerances, and hard anodized for strength and durability.
Lightweight, convenient, effective, and affordable.
Ideal for use with Gates Carbon Drive belt systems. Works with chains, too!

8mm hex fitting is slightly oversize to provide for real-world conditions and the presence of dirt or debris.

The ROCKERBONE Rocker Dropout Tensioner offers more surface area interface with the dropout than stock bolts and washers alone, in turn providing a more secure purchase for slip-free riding.

To work properly, the ROCKERBONE Rocker Dropout Tensionermust be used with the included pairs of TUFFBOLTZ and washers, which are custom machined for full thread engagement and plated for extreme durability.
(Using a longer bolt may result in interference with cassette lockrings.)



  • 1) Ensure that all dropout surfaces -- frame, insert, ROCKERBONE -- are clean, dry, and free of any grease or lubricants.
  • 2) Using the supplied hardware, assemble each Rocker unit as normal, with the ROCKERBONE between the TUFFBOLTZ/washer and the frame, with the thicker end toward the front of the bike.
  • 3) With belt/chain engaged with ring/cog and ready to tension, pull the wheel rearward by hand as normal until approx. 90% of desired tension with the rear axle perpendicular to the frame centerline. 
  • 4) Lightly torque Right/Drive side bolts until Rocker stays in position (approx. 8Nm).
  • 5) Pull the Left/Non-Drive side Rocker an additional 5mm rearward, displacing the wheel slightly to the left of frame centerline, and tighten bolts enough to prevent further movement (approx. 12Nm).
  • 6) Using a 19mm open wrench or an 8mm hex wrench on the Right/Drive side ROCKERBONE, rotate the tool downward (clockwise) until desired belt tension is reached. Torque bolts to 25Nm/18ft-lbs as specified by Paragon Machine Works.
  • 7) If necessary to center the wheel, follow the same procedure on the Left/Non-Drive side ROCKERBONE, rotating the tool downward (counter-clockwise) until the wheel is centered. Torque bolts to 25Nm/18ft-lbs as normal.


Kit Includes:
2x) PDX TI RockerBones (black or silver)
4x) Zinc Plated M8 x 1.25 x 18 socket head bolts
4x) Stainless Steel M8 Recessed Washers.

MATERIAL: Cast Aluminum
DIMENSIONS: 68x19x9 mm
SINGLE WEIGHT: 15g / 0.6oz  (40g / 1.6oz including bolts + washers)


For more information about Rocker-style dropouts, please consult Paragon Machine Works.