Just noticed that the crappy old front brake on my fixed gear bike flexes forward when force is applied, i.e. the rim pushes it forward a lot. It's a longer-pull brake, maybe made for bigger wheels/fenders, but it looks like it's flexing forward quite a bit, maybe an inch, maybe more. Is this in danger of breaking, or is it normal braking ? I tightened the binder bolt on back of the headtube, but that doesn't seem to have done much. What else should I do?