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Safety helmets for motorcycle riding are produced from a variety of different materials. Carbon fiber and fiberglass are two of the most common materials in commercially available helmets. They have different physical properties and different strengths and weaknesses.
Construction
Manufacturers make fiberglass and carbon fiber helmets in a fairly similar way. The only real differences are the chemical compositions of the solutions used to build the shell. Strands of fibers are gradually built up in layers inside a mold. The manufacturer seals each layer in place with a resin, which is allowed to dry before pasting the next layer over the top. The fibers in each layer run at different angles to each other, creating greater torsional strength between the layers.
Weight
Carbon fiber is significantly lighter than fiberglass. Its common in aircraft, sports cars and military equipment for this reason. A lightweight helmet improves rider safety because it reduces fatigue. Helmet design is usually a trade-off between the different properties of a material. The lighter a helmet is, the easier it is for the rider to wear, but if its too light, the strength will be compromised.
Resilience
Fiberglass helmets are strong, and have been proven as effective motorcycle helmets over many years of use. However, fiberglass is brittle compared to carbon fiber, and tends to dissipate impact energy by shattering. For most impacts, this is not a problem; the helmet absorbs the impact and rider is OK. But when a rider suffers two impacts in a crash, for instance, falling off the bike then sliding into an obstacle, The helmet could be compromised by the first impact, allowing the second to harm the rider. Carbon fiber helmets have significantly more flex and "give" in the outer shell, offering protection from accidents of this type.
Price
Fiberglass has always been the cheaper option for motorcycle helmets. Carbon fiber is a "prestige" material and commands a high price tag due to its higher costs of production and manufacturing. In some ways, this reflects the appropriate market for each type. The high-priced carbon helmets are more likely to be purchased by people riding high-performance race-ready machines, that are more likely to be involved in high-speed crashes that would require the additional protection. Fiberglass helmets are more than adequate for those riders on slower machines, more likely to be involved in minor spills.
