Carbon fiber composite inspection


Carbon fiber is among the strongest materials used in bicycle manufacture. However, carbon has unique qualities, different from metal parts, and must be inspected carefully for damage and fatigue stress.

Warning

A damaged carbon fiber part can fail suddenly, causing serious injury or death. Inspect a carbon fiber bicycle or parts for damage frequently. If you suspect a carbon fiber part is damaged, replace the part before riding or take the bicycle to you LeMond dealer for service.

Inspecting carbon fiber composite parts

Carefully inspect your frame and components for signs of fatigue before and after each ride. Even if you perform regular inspections, if you exceed the limit of strength of your bicycle or a given part, it will fail. The Limited Lifetime warranty offered with your bicycle does not mean that your bicycle cannot break; it only means the bicycle is subject to the terms of the warranty. The manner in which you ride will determine whether your bicycle and its parts will last your lifetime. If you ride hard or aggressively, you should replace the bicycle and/or its parts more often than riders who ride smoothly or cautiously. There are many variables to this equation: weight, speed, technique, terrain, maintenance, riding environment (humidity, salinity, temperature, etc.), and the frame or part itself- so it is impossible to give a precise timetable for replacement. If you aren't sure, ask your dealer. But as a rule, it is better to err on the safe side and replace the bicycle or parts more frequently.

Unlike metal parts, carbon composite parts that have been damaged may not bend, bulge, or deform; a damaged part may appear to be normal to a cursory glance. After any high force load, like a crash or other impact to your bicycle, thoroughly inspect all the parts of your bicycle, and use the following procedures to inspect carbon composite parts:

Check for scratches, gouges, or other surface problems.

Check the part for loss of rigidity.

Check the part for delamination.

Listen for unusual noises.

These tests may not be conclusive. The tests are difficult to describe, so as an aid to describing the tests we provide a movie of a composite part inspection. If you have any doubts about the integrity of a part, do not ride the bicycle.

To check a part for surface problems (visual test)

Be very careful when handling carbon fiber parts that are suspected of damage. When a composite part is damaged, there is a possibility that individual fibers may be exposed. Carbon fibers are thinner than a human hair, but quite stiff. If the point of one of these fibers is pressed against your skin, it could pierce your skin like a needle.

1. Clean the part thoroughly with a damp cloth.

2. Look closely for problems:

scratches

gouges

cracks

loose fibers (which will appear like thin hairs)

other surface flaws

If the part has any problems, do not ride the bicycle. Take the bicycle to your LeMond dealer for replacement or further inspection.

To check a part for loss of rigidity (flex test)

Use the part in a normal manner (without actually riding) while someone watches carefully for unexpected movement.

As an example, if you suspect a composite seatpost has been damaged, sit gently on the saddle while someone watches to see if the seatpost flexes.

If the helper sees the part flex unexpectedly, or if the part feels less rigid than it should be, do not ride the bicycle. Take the bicycle to your LeMond dealer for replacement or further inspection.

To check a part for delamination (tap test)

1. Clean the part thoroughly with a damp cloth.

2. With a nickel or other coin, tap the part near any possible damage and places where the part is known to be in good condition (or use a similar part).

3. Listen carefully for variations in sound, especially a hollow sound, "dead" tone, or any sound indicating that the part is not solid.

If the part makes any noise other than a hard, solid tap sound, do not ride the bicycle. Take the bicycle to your LeMond dealer for replacement or further inspection.


Check clamping surfaces

Before assembling a carbon part, make sure the clamp is compatible and that the parts are clean.


Related Topics