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Carbon Fibre Bicycle Inspections: A Neglected Safety Aspect In The Cycling Industry

Carbon fibre composites are one of the most common materials in the bicycle industry.
However, these materials may sustain damage or contain defects which are not detectable on the external surface of the object or by the human eye.
Areas of damage or defect reduce the integrity of the component and can result in catastrophic failures, ultimately resulting in injury or even death.

There is no existing standardisation, certification, or body of data/knowledge on the risk and repairs of various types of carbon damage within the cycling industry

Here are just two of the many types of damage/defect with vastly different characteristics (neither of which may be visible from the surface):

Impact Damage

During impacts, force can be transferred to the internal structure, leaving the external surface looking relatively clear. Bicycles should be inspected for non-visible damage such as delaminations and fibre breakages

Bridging Voids

Bridging voids typically develop during manufacturing. They may be large, cannot be detected on surface or interior via visual methods and may not be detected via a tap test.

Existing Solutions

Many cyclists and mechanics are familiar with the “tap test”, although this method has major limitations (cannot detect certain types of damage/defect such as bridging voids, and cannot detect the size, depth or extent of damage). Therefore, your safety should not rely on this method.

Current best practice is often a costly solution to strip and ship a bicycle to one of the few bicycle inspectors/repairers with no standardisation or certification of processes across this industry.

Cycle Inspect's Solution

Cycle Inspect brings training, technology, diagnostics, and standardised reporting of carbon fibre inspections to the cycling industry. We train and accredit trusted retailers and mechanics to perform this service in-house, avoiding time-consuming and costly processes of stripping and shipping bikes across the state or country.

Cycle Inspect has developed patent-pending technology including a risk assessment platform and standardised reporting methods which creates a standardised and trustworthy inspection process and helps guide new NDT trainees through the inspection and reporting process.

We are a data-driven company and have collaborated with university researchers and many industry experts to select suitable technologies, develop suitable procedures and risk assessment platform, and developed a training program that is appropriate for novice NDT trainees.

We teach important foundational theory of carbon fibre bicycle frames and components and help to develop the practical skills and experience necessary to confidently perform inspections.

Cycle Inspect is not invested in the repair industry and pride ourselves on helping your local retailer and mechanic to provided unbiased assessments of your bicycle.

Non-Destructive (NDT) Methods For Carbon Fibre Bicycle Inspections

Damage and defects to carbon fibre bicycle components can be invisible to the human eye due to being on the interior of the component or within the carbon structure itself.

Therefore, non-destructive testing methods are essential components to:
1. Identify if damage is present  
2. Classify the type and size of damage  
3. Assess the risk of a catastrophic failure or damage escalation  
4.Suggest whether a repair is possible and an appropriate method

Cycle Inspect’s research with Deakin University put several different methods of carbon fibre inspection to the test.

We exposed carbon tubes to damage and then examined the ability and limitations of various technologies to detect the damage.
1. Ultrasonic testing is accessible, mobile and accurate, although specialised equipment is required.
2. Was able to determine the type, size, and depth of the damage.
3. However, training, technique, calibrations, and experience are required.
This is Cycle Inspect’s preferred primary bicycle inspection tool.
1. X-Ray effectively identified damage, with strong potential for accurate inspections.
2. However, it is relatively inaccessible, expensive, and time-consuming.
3. Not a practical solution for retail sector or mobile mechanics within the cycling industry.
1. Highly accessible but limited by low frequencies and an individual’s auditory processing skills.
2. Limited to detecting presence of some damages or defects, but not the type, size, depth, or overall risk and repair solutions.
3. Always requires follow-up with more suitable methods.
1. An accessible and practical method
2. Thermography had difficulties when compared with Ultrasound and X-Ray in detecting smaller damages e.g. where smaller loads had been applied to a carbon fibre tube.

Tap Testing: Not A Reliable Inspection Solution For The Cycling Industry

Most cyclists are familiar with the tap test (or coin test), in which a specialised tap hammer or coin are gently tapped against their frame or component while the user listens for audible changes in sound, signifying the presence or lack thereof of underlying damage or defects.

This method is logical and stems from the non-destructive testing (NDT) industry. However, there are many aspects and limitations which are often overlooked in the cycling industry, likely due to the availability and practicality of this method, and the inaccessibility of more robust methods.

Limitations

1. The accuracy of this method is limited by the auditory processing skills of the individual. Most individuals could only tell the presence of large damages or defects where a substantial change in sound occurs.

2.The accuracy of tap testing is also limited by the technique of the user i.e. the ability to create a reliable sound via their tapping motion.

3.Soundwaves (waves detectable by human hearing) by definition only have a limited wavelength and limited properties when it comes to penetrating various materials.

4.The presence (or lack thereof) for some damages such as large disbonds maybe detectable, but not smaller damages or defects such as voids, in which the carbon fibres may be in tact but not in the manufacturer’s intended composition.

5. In order to accurately classify the type of damage (e.g. a delamination or a bridging void), a multidimensional approach is needed i.e. we need to know the position, orientation, length, width, and depth of the damage. Only with all of these pieces of information can we attempt to accurately classify damage, understand the risks, and determine whether a repair is possible and how to go about it. Tap testing only enables us to determine whether there may or may not be some types of (typically large) damage.

Cycle Inspect suggests that more effective methods such as Ultrasonic Testing should be used to determine the presence of damage and defects, and the characteristics and risk imposed by these in bicycle components.

When To Inspect

Currently, when a customer takes their bicycle into a retailer/mechanic either for a general service or a known issue, mechanics typically perform a general bicycle inspection in front of the customer to identify any obvious issues ahead of the service/repair. They then perform ongoing analysis throughout their service/repair work. However, these processes are usually limited to areas of mechanical concern e.g. "are the wheels true?", "are the brakes functioning?", "are the gears changing correctly?", "is the chain stretched?", "is the suspension functioning properly?".

Little attention is usually given to observable damage of a carbon fibre bicycle frame or component e.g. scratches, chips, and surface irregularities. Yet, carbon fibre integrity may deteriorate over time if exposed to the moisture and UV light, and surface level irregularities may be indicative of deeper structural damage requiring detailed analysis via non-destructive testing.

This limited attention to irregularities and damage is likely due to the fact that mechanics are not trained to analyse carbon fibre structures and do not have the technology and expertise to do so. Only large and obvious issues are detected via visual observation, and detailed analysis or repair requires your bike to be stripped and shipped across the country to one of the few experts who can perform this service, requiring significant time and costs. Additionally, these services are not standardised in any way.

Here at Cycle Inspect, we believe that carbon fibre inspection should be a standard inclusion in service offerings and a standard function that all trusted bicycle mechanics are trained to perform. Of course, we do not expect that every bicycle coming through the doors should have ultrasonic testing applied to the entire frame and components, but the surface should at least be inspected and further analysis performed on site, with further actions taken as necessary.

Through Cycle Inspect's training and technology, this can now be undertaken relatively quickly and cheaply by your local trusted mechanic, without the need to strip and ship your bicycle across the country.
The most obvious time for bicycle inspection is immediately following incidents such as a crash, drop or other impact. Currently, many cyclists will have their bicycle inspected only if they observe significant damage via visual inspection. However, carbon fibre bicycle components can appear relatively fine on the surface, because the impact may have transferred through the carbon structure, causing unobservable delaminations and fibre fractures.

At Cycle Inspect, we believe a bicycle should be inspected immediately after any impact via non-destructive testing methods. Only this will provide piece of mind and ensure that unobservable damage does not go unchecked, leading to potentially catastrophic outcomes in future.
Currently, the purchase of a used bicycle is often somewhat of a lottery. A cyclist may unknowingly purchase a bicycle or component that contains significant structural damage or defects. This is obviously a significant safety risk, but also a financial risk as many bicycles and components do not have transferrable warranties or extensive warranty periods.

We believe that all used bicycles and components should be submitted to a rigorous inspection prior to sale, to increase confidence that the bicycle is free of damage or defects that could potentially lead to catastrophic failures. Previously this has been impractical due to the cost and logistics of shipping these back and forth to inspectors. However, with Cycle Inspect making this service available to your local trusted retailer and mechanic, we believe this issue cannot be ignored any longer.