To continue the post above, anecdotally, I've used 100mm brake arms with short-pull levers before on my 1997 Trek 750. This is the combination that will give you the most mechanical advantage, at the expense of a very small window for brake adjustment tolerance (rims have to be very straight, etc.). It did work pretty well, and it would absolutely stop On. A. Dime. Like, right now. I did eventually change the brake configuration on it to something else, but that combination does work sometimes. That Raleigh bike I mentioned above was the opposite of that -- long-pull levers paired with short brake arms. That combination gives the rider the least amount of mechanical advantage.