How to Know If a Defect Caused a Bicycle Crash
Common signs that a bicycle defect or improper assembly caused your crash — and exactly what to do to preserve evidence and protect your claim.
By Attorney Dan D'Angelo
Trial Lawyer · Brain Injury Advocate · Avid Cyclist

A bicycle must have component parts for the rider to safely occupy, propel, steer, and stop. A defect that unexpectedly disrupts these essential functions can cause the rider to lose control, fall, or crash, resulting in serious injuries or death.
Determining if a bicycle defect caused a crash requires specialized knowledge of bicycle design, manufacture, mechanics, assembly, and safety standards. If you suspect a defect caused your crash and injuries, here are key questions to help you identify if a bicycle defect may be involved and what to do next.
What is a bicycle defect?
A bicycle defect does not necessarily involve a mechanical or functional fault or flaw but can be anything that makes a bicycle unreasonably dangerous. An unreasonable danger is a risk of harm an ordinary user would not ordinarily expect or that is not outweighed by the benefits of the product design.
The cause of a bicycle or component part defect can come from the design, manufacture, or assembly of the bicycle, or from an inadequate warning or instruction about any risk of harm from the intended or expected use of the bicycle.
Common signs a defect may have caused the crash
- A component part of the bicycle unexpectedly detaches while riding — pedal from crank arm, chainring or crank arm from spindle, wheels not secured by bolts or quick release, seat from seat post, or handlebar from stem.
- A component unexpectedly loosens or breaks causing it to move, shift, or slip while steering, braking, or riding — brake levers, hoods, steerer tube, stem, handlebar, seat, seat post, crankset, chainring, crank arms, wheels, or rims.
- A component fails to operate as expected — brake does not engage, loss of steering control from separation of stem and steerer tube, frame/fork/wheel rim breaks or cracks, sudden tire airloss.
- The crash occurred shortly after purchase of a new bicycle.
- No misuse, such as exceeding the bicycle's intended use or weight limit.
- The bicycle or component does not comply with state or federal code, standard, or regulation.
- The bicycle or component is part of a manufacturer or government agency hazard warning or product recall.
What to do next if you suspect a defect
- Preserve the bicycle in its post-crash condition for inspection. Do not attempt to fix it. Do not return it to the store of purchase.
- Preserve clothes, equipment, and electronic recording devices (bike computer, Apple Watch, etc.) worn at the time.
- Preserve documentation — proof of purchase, maintenance records, and User and Owner's Manuals.
- Don't wait to contact an attorney. Notifying the manufacturer and seller within a certain period may be required for product defect claims.
Knowledge about bicycle component design, manufacture, mechanics, assembly, and safety standards matters for winning bicycle product defect and negligent assembly cases. Dan is an avid cyclist, focuses his law practice on bicycle cases, and has experience litigating bicycle defect and negligent assembly issues against large national corporate defendants.
Have a question about your case?
Attorney Dan D'Angelo offers free consultations for brain injury and cycling accident victims throughout Colorado.
About the Author
Attorney Dan D'Angelo
Trial Lawyer · Brain Injury Advocate · Avid Cyclist
Attorney Dan D'Angelo founded D'Angelo Law Office, P.C. in 2009 and Bike Brain Law to focus exclusively on traumatic brain injury and cycling injury cases in Colorado. An avid cyclist himself, Dan combines deep TBI science knowledge with hands-on cycling experience to build winning cases against insurance companies and corporations that put profits over safety.
- Practicing Colorado personal injury attorney since 2009
- Focused practice in TBI and bicycle injury litigation
- Multi-million dollar settlements and verdicts for injury victims
- Avid road and commuter cyclist



