A. (Ellis Walentine) "I'm not quite sure what the problem is. All routers, including DeWalt models, are designed to do edge beading with standard length bits, assuming the base of the router is in contact with the surface of the wood and not set off by a thick template or other obstacle. The bit doesn't need to bottom out in the collet in order to be held adequately, but for every diameter of bit and shank there's a point at which safety and performance begin to drop off. For safety's sake, I'd say never grip less than an inch of shank, although in a pinch you could get away with less than that if you work carefully and don't try to hog too much wood too quickly.

The length of the shank is usually determined by the type and heft of the bit. Manufacturers don't want you to have too much mass extended too far from the collet, and neither should you; so if the bit has a short shank, that's a message. Also, keep in mind that 1/4" shanks are more flexible and more likely to chatter (and break) than 1/2" shanks, so they're shorter and you can't extend them as far."

A. (Ian Kirby) "As a rule of thumb, for safety's sake and quality of cut, I think half of the router bit should be held in the collet. And router bits are not offered with long or short shanks as an alternative."