Quick Release Failures Expert Article

This article provides an introduction to quick release operation and associated failures. The experts at Robson Forensic have experience investigating the performance of quick release mechanisms in a broad range of products, including bicycles, knee walkers, and other mobility devices.

Quick Release Expert Witness

Why Do Quick Releases Fail?

A quick release (QR) is a device found on millions of bicycles sold in the United States each year. Its function is to attach a bicycle’s wheel to the frame or fork. Additionally, quick releases can clamp a bicycle’s seatpost into the frame and allow for tool-free seat height adjustment. The device consists of a threaded rod with a lever-actuated cam on one end.

Figure 1: Anatomy of Quick Release Mechanism

The tension that allows the quick release to safely stay closed is provided by the actual stretch of the skewer shaft. When the device is not adjusted properly, failures can be caused by too little or too much tension:

  • If the QR is too loose it can come open while riding, leading to the potential of a wheel falling out or a bicycle saddle slamming suddenly down to its lowest level. Either of these situations can lead to a loss of control and a crash.
  • If the QR is too tight the shaft can be permanently elongated, preventing proper closing tension from being achieved. This too can lead to the QR opening unexpectedly.

Avoiding Quick Release Failures

The adjusting nut opposite the lever-actuated cam must be spun such that clamping force is generated that will stretch the QR shaft by a very specific distance (usually less than 1 millimeter). If this sounds complicated, that is because it is. To a novice bicycle buyer, this information should come from an informed bicycle shop employee or other trained professional. Proper operation of a bicycle quick release seems straightforward, but instruction and practice can ensure that a QR is closed safely and consistently.

Figure 2: Operation of Quick Release

Disc Brake and Quick Release Combination

On bicycles equipped with disc brakes and quick release front axles, certain QR designs create a dangerous condition such that a loose QR lever could swing into the spinning disc brake rotor. This could cause the front wheel to lock up suddenly and pitch the rider over the handlebars. Beginning in 2015, a sweeping recall in the bicycle industry has addressed this potential hazard. To date, over 2.5 million bicycles sold in the US have been included in the recall.

Alternative Designs for Wheel Retention

Many bicycles are moving from quick release axles to ‘through axles.’ While still retaining the ability to remove wheels for maintenance and transport without tools, through axles provide performance benefits such as added stiffness and, potentially, weight savings. Through axles can also reduce the hazard of front wheel ejection on bicycles equipped with disc brakes. Bicycles using forks designed for through axles do not have open dropouts; therefore a loose through axle does not have the same potential hazards as a loose quick release.

Figure 3: Bicycle Dropout Design

Non-Bicycle Quick Release Investigations

Quick release mechanisms utilized in non-bicycle applications are susceptible to the same issues described throughout this article. Often utilized to provide tool free adjustability in medical mobility equipment or recreational vehicles, the failure of a quick release device can lead to a loss of control and crash/fall. The issues involving the product and instruction in non-bicycle applications are identical to bicycle applications and our experts have experience investigating and testifying in cases involving a wide variety of consumer products.

Quick Release & Bicycle Component Failure Investigations

The experts at Robson Forensic are regularly retained in bicycle design, assembly, maintenance and repair cases involving falls, collisions, traumatic brains injuries and deaths that are associated with the use and misuse of bicycles. The scope of our investigations can encompass rider action, instruction, event organization, bicycle design, assembly and maintenance.

To discuss your case with an expert, submit an inquiry.


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