Because at that time, Keke's motorcycle's performance was relatively poor, several grades lower than Sang Biaohu's, and with additional factors, she didn't win a single race last year. So, after she switched motorcycles, she specifically asked Sang Biaohu for a one-on-one meeting, just to challenge him and to get revenge for last year's losses!
The competition between the two naturally involved stakes. Keke's condition was that if Sang Biaohu lost, he must quit the racing world forever, and give her the motorcycle he was riding.
Sang Biaohu had no objections and agreed right away, but he also proposed a condition, that if he won the race, Keke would have to sleep with him and agree to become his girlfriend.
Since Keke's new motorcycle was very powerful and she had specifically modified the engine, making the horsepower even more fierce than the original, she was very confident of winning and without thinking twice, she accepted Sang Biaohu's terms.
