运用力学模型和运动力学，对自行车紧急制动时发生前翻的安全性问题进行了理论分析和实证，提出了紧急制动时的安全速率和制动力，并结合国际先进标准的要求，提出安全骑行的要求和自行车刹车安全制动力的检测要求，确保安全骑行。结果表明：自行车发生前翻的3个必要条件为μ > l₁/h，a_- > g ·l₁/h，v > √2g·Δh。

The safety of bicycle overturn caused by emergency brake was analyzed and verified through mechanical models and kinematic mechanics. The parameters of the safety speed and brake force for emergency brake were derived. According to the requirements of international advanced standard, the requirements for safety riding and the test requirements for safety brake force of bicycles were put forward for the safe cycling. The results show that:three necessary conditions for bicycle overturn were μ > l₁/h,a_- > g ·l₁/h and v > √2g·Δh.