Modern bike frames are made of carbon fibre-reinforced plastics, which is exceptionally light

Thermal imaging cameras from Flir Systems are being used for pulse thermography quality tests in order to find flaws in modern bicycle frames made of carbon fibre reinforced plastics

“Usually bikes with carbon fibre-based frames do not come cheap, so these tests are important for rider safety, and also serve to protect your assets,” explains Volker Carl, pulse thermography specialist and company owner.

Checking used bikes

Carl says customers have different reasons seeking tests. “Some might have had a crash with their bike and want to make sure this accident has not caused invisible defects. Others have bought a second hand bike which looks perfect on the surface but they want to make sure that it contains no hidden flaws.”

But it’s not only accidents that cause flaws. “Carbon based frames can be vulnerable to specific types of stress. A bike might fall over and hit the edge of the curb for instance. Even if you tighten the roof-rack clamp or derailleur clamp too tightly when you’re preparing your bike for transport, can cause invisible cracks. On the surface, everything might look fine, but in reality the bike is damaged.”

Using a bike with such invisible damage can be quite dangerous. “Imagine you’re descending from a mountain at high speed and suddenly in a bend in the road your bike breaks. That really is a very dangerous situation. Not only can such accidents be prevented by detecting defects beforehand, in most cases it is also possible to repair these defects. This can often result in a bike that is even stronger than the original design.”

In order to find out whether such repairs are necessary, bike owners can have their bikes scanned by Carl’s Flir thermal imaging camera, using a method called pulse thermography. “We trigger a thermal impulse and use the Flir thermal imaging camera to trace the heat flow. Differences in the heat flow can indicate material defects. The thermal data collected with the thermal imaging camera provides a unique insight into the flaws in carbon fibre-reinforced materials.”

Extremely accurate

The thermal imaging camera used by Carl is the Flir SC7000. The cooled Indium antimonide (InSb) detector is extremely sensitive and provides high contrast thermal images at a resolution of 640 x 512 pixels.

Currently Carl is also working on a new setup with a Flir SC645 thermal imaging camera. “The Flir SC645 is slightly less sensitive, but the difference in price and in maintenance cost with the SC7000 will allow me to charge lower fees for the quality tests.”

New type of client

This new setup will open the door for a new type of customer, Carl hopes. “Currently my customers are mostly professionals and semi-professionals who use their bikes very often. They really need to be sure that the bike is absolutely safe, so I expect that this type of customer will still prefer the more accurate tests using the Flir SC7000 thermal imaging camera. But I think that hobbyists who currently refrain from this type of test will be attracted to the quality tests using the Flir SC645 because of the lower fees.”