<<The Finishing Touches
Someone once rode my GNAT, built a copy, then complained that when he sat on it, the front-wheel tracking was thrown completely out. I did not think that was my fault!
Provided the steering is adjusted correctly, tracking will not be affected by suspension movement. Adjustment consists of sliding the steering arm (to which the inner trackrod balljonts are attached; see picture below) to the correct height. If it is too high, the wheels will toe in as they rise; too low, and they will toe out;
You may be able to mouse over the picture above to see the front wheel of a GNAT at both extremities of its movement. If you have disabled Java script, see the pictures on June06 update. You will notice that the front wheel points in the same direction in both pictures.
As well as getting the inner steerer arm the correct height, you also need each trackrod to be similar lengths, so that the arm is pointing directly backwards when the wheels are straight ahead. You can see the arm (just) in the picture on the right. It fixes to the steerer tube running through the chassis by a 6mm pinch bolt tightened with a hexagon key.
The GNAT has about five inches of suspension travel on the front wheels. This is the maximum amount of movement before something, probably a balljoint or trackrod, would get bent. In practice, you do not need anything like this amount of suspension movement. On the road, quality of ride comes from the speed with which the suspension can respond to bumps, rather than the amount of travel. The GNAT's suspension is very effective at removing vibration.