One of the most critical aspects of defining how a bike rides is ‘trail’. This figure describes the distance between the point at which an imaginary line through the middle of the steerer tube would hit the ground, and the point at which the tyre actually hits the ground. The longer this distance, the slower is response to steering input – and conversely very short trail tends towards ‘twitchy’ steering. As you can see from the picture the more offset (rake) the less trail.
That can be fine, except a low rake rigid fork on a steep head angle bike does not make for the most comfortable ride. So how to achieve the best of all worlds? Have a long rigid fork with a good amount of rake. Then if you run an 80mm travel suspension fork, it drops the front end, steepens the head angle, and your bike doesn’t turn into the Queen Mary for the sake of a bit of squish. Alternatively this also gives you the option of a longer travel fork slowing the steering up a bit if you’re into the type of riding which might ask for less responsive handling.