Even at the proud age of 87, Günter Hommel can't stop enriching the bike world with his inventions. The trained mechanical engineer is an inventor with heart and soul. His latest development to date was patented just last August. A friend from Oberstdorf inspired him to dedicate himself to the subject of brake discs on bicycles. He complained that the brakes were too weak and, in combination with a high system weight, were permanently at their limit on steep terrain. Hommel thought to himself that this should be solvable and has been working on a solution to the problem since 2019.
However, Hommel had to abandon the initial idea of using sodium bicarbonate as a coolant in the brake disc. Baking soda is still used in the automotive sector to cool valve tappets or to absorb heat in flight recorders. In the case of his brake disc, however, production and processing would have been too complex and therefore impractical. High-temperature soldering would have been necessary to join the individual parts together.
Copper provided the solution
But Hommel persisted and searched for a practicable and equally efficient alternative. As copper has extremely good thermal conductivity, which is around six times higher than steel or more than twice as high as aluminium, Hommel found what he was looking for. His special brake disc therefore consists of two stainless steel cover discs with a copper disc as the core and wings for internal ventilation.
This keeps the disc much cooler compared to conventional rotors and not only increases stability, but also reduces abrasion. The copper core can also be recycled when the cover discs are worn out. A brake disc with a diameter of 180 millimetres should weigh 289 grams. Tests on the developers' in-house test bench show that the new brake disc remains significantly cooler than the current competitor products. This makes it ideal for heavy e-MTBs, cargo bikes or even light motorbikes, Hommel promises.
The father-son team is still looking for producers for the innovative brake disc. Enquiries at info@bike-magazin.de
