CJA Crank Arm Shortener



The CJA Crank Arm Shortener (also known as a bicycle crank length adapter) offers different pedal positions to assist cyclists with limited knee or hip flexion, or simply with shorter legs.

This model uses adjustable cams to capture the side of the existing crank arm, making it suitable for a wide range of cranks widths, and curvature profiles.

In stock

SKU: 2440 Category: Tags: , , ,
Brand: CJ Ackley Machine Company


This is an alternative design to the Orthopedal model.  The main advantage is better suitability for use on curved crank arms, but otherwise installation, range of adjustment and functionality are comparable.

Currently only available as a pair.

Crank Arm Shortener Features and Benefits

  • Manufactured in the USA from high-grade aluminum alloy into an attractive shape that easily bolts onto your existing bicycle crank.
  • Handcrafted Stainless Steel Bolts provide strength and durability
  • Useful for cyclists with short inseams (under 80cm) who would benefit from turning a smaller radius to resolve or prevent knee pain.
  • Pivotal for cyclists with limited lower limb range of motion due to injury or surgery
  • Reduces stress on the knees and hips
  • May reduce pain or discomfort
  • NOTE: The use of this product will increase the stance width of the cyclist, equivalent to the width of the crank arm on each side.
  • Installs in 10 minutes


  • Works well with curved crank arms, as well as straight crank arms.
  • Standard 9/16″ pedal axle holes. NOT suitable for older style exercise bikes using 1/2″ pedal axles.
  • Suitable for use on regular bicycles, e-bikes, and indoor exercise bikes such as the Peloton bike
  • 210 lb weight limit on upright bikes. Do not stand on pedals continuously.

What’s in the Box?

  • A pair comes with instructions, R & L sides, mounting hardware, 1/4 Allen key and a small single application loctite tube.


  • Shortens crank arms by 24, 41, 58 and 75mm  (i.e 4 pedal mounting holes
  • Standard 9/16″ pedal axle holes
  • Adjustable cams to fit a variety of crankarm widths from 23 to 42mm

Additional information

Weight 0.9 lbs
Dimensions 8.5 × 5.3 × 1.6 in


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