This happens in chapter 22, during the heart of the escape sequence. Jonas fumbles a little on the bike, and grabs Gabriel to steady him and make sure he won't be injured. Gabe survives the incident unharmed; "but Jonas's ankle was twisted, and his knees were scraped and raw, blood seeping through his torn trousers" (p. 170).
This incident causes Jonas to start riding his bike in the daytime instead of only at night. The roughness of the road makes him more cautious, and he needs to see where he is going more clearly than before.