So the other day I was at the local bike shop getting some handlebar tape. I had my bike (trek 400 series) with me and had removed my front brake and the old tape. While in the store I was told multiple times that I needed to run a front brake. I understand this and would never ride without one. I tried to explain that I was going to repaint the bike and wrap the handlebars so that's why they saw no break. They continued to emphasize the importance of a front brake anyway. But anyway, they said that my frame wouldn't be able to stand being stopped by the pedals alone and that the back tire would "rip off". I don't really understand this. I figure the chain would break before my tire would go. Are they trying to tell me my frame isn't strong enough or what?