The trouble with bike helmets is, well, bike helmets, No matter how classy-looking and durable bike helmets have become, their wearers still have to lug them around when they step-off their bikes. That's inconvenient.

But more important than fashionability is safety. The puzzling refusal of many cyclistrs to wear helmets is a key factor leading to the grim statistics that 850 cyclists were killed in the United States in 2016. In addition, more than 85,000 cyslists suffered traumatic brain injuries after being hurled from, or falling off, their bikes.

Park & Diamond, an American engineering start-up based in the state of Virginia, has developed a collapsible bike helmet it claims is safer and more comfortable than traditional helmets. The Park & Diamond helmet, or helmet cap, resembles a baseball cap.

The features of the Park & Diamond helmet cap were based on inputs from interviews of thousands of potential customers. Park & Diamond discovered three major qualities cyclists want in a bike helmet: comfort, style and portability. They set to work on developing their helmet cap based on these inputs, and revealed their product after three years of research and development work.

Park & Diamond says its helmet cap is ultra-portable. The helmet cap is designed to be rolled-up and fits into a custom water bottle-sized case. It also stores easily in a backpack or handbag.

The Park & Diamond helmet cap, which comes with a safety chin strap, is more efficient at absorbing and dissipating energy than traditional bike helmets. It complies with the U.S. Consumer Product Safety Commission (CPSC); EU EN-1078 safety certification and Canadian cycling helmet CAN-CSA-D113.2-M standards.

The collapsible helmet cap is made from an undisclosed material used in aircraft. The company said the cap is tough yet flexible enough to be folded.  The helmet cap, which weighs just 8 ounces, can also be personalized for individual wearers. The cap's breathable and stylish skin material can be replaced and is hand washable.

The cap's outer shell features a geometric pattern that's better at absorbing energy than traditional and far heavier bike helmets. In September, Park & Diamond sought to raise $50,000 on the crowdfunding site Indiegogo. Within 24 hours, they had raised three times that amount, and have since exceeded $500,000.

From the very first day, we were blown away by the response, said co-founder David Hall.  Now, he and the other co-founder, Jordan Klein, will customize the design even further, and will develop new styles and designer collaborations. New models, one of which will be in the shape of a beanie, are being developed using the same technology.