Before you lay down some hard-earned scratch for a back protector, there are essentially two things to remember. First, wearing one can dramatically increase the chances of escaping serious injury in a fall, and not just on the racetrack. Second, never assume anything called a back protector will actually protect your back. While the idea is simple-distribute and absorb impact before it can damage the mind-bogglingly complex structure known in medical parlance as the vertebral column-actually getting the job done is far more complicated. We've come a long way from Barry Sheene's idea of pop-riveting a few faceshields together. Hard plastic or soft foam alone don't cut it anymore.
These days, most of the stuff you'd want to wear carries a "CE Approved" logo, which means it's passed a series of impact tests mandated for protective motorcycle gear sold within the European Union. The CE standard governing back protectors (EN1621-2) uses the same impact energy as shoulder and elbow armor (50 joules), but allows less of that force to be transmitted through to the human underneath: 18 Kilonewtons (kN) for Level 1-rated protectors, and half that for higher-performance Level 2 products. Though no benchmark is perfect, the CE rating is a good way to separate the genuinely good stuff from the maybe not so good.