Out for a quick 25 on the tandem this morning on the bike trail. Counted al least six riders with no helmets on. A guy passes us, runs the blind t-intersection maintenance road stop sign at the Aquatic Center and plows right into the side of a CalTrans truck. He got really lucky. Minor cuts and scrapes on his face and (probably) a broken wrist. His helmet was unbroken, but really scarred up. He was out cold for a short time. When he woke up, he had no recollection of what happened. Could have been a lot more serious if he didn't have his helmet on.