On a club ride a while back, there was a rock in the bike lane on Foothill Expressway. Most people went around it, but a cyclist near the back of the group hit it directly, getting quite a jolt. Luckily, he managed to avoid a crash, but did get a pinch flat. On a LDT ride, a large pack of riders entered onto a bike path with a pole in the middle of the entrance. One cyclist later reported “this pole suddenly came at me and knocked me down.” Unfortunately, this cyclist sustained some minor injuries that kept him off the bike for a few weeks. Both of these incidents might have been averted with proper communication.
Communication is very important when bicycling in a group. When you see a hazard ahead or a car coming up behind (or in front on a narrow road), please communicate this to your riding partners. Usually a verbal signal is best such as "car up" or "rock" or "gravel." At other times pointing out a hazard with a hand signal is best (remember that when biking we always point at the hazard). The important thing is to COMMUNICATE!