One size fits some but does not fit all. The only adjustment is with the rear suspension . Depending on what setting you have it on it both adjusts the seat height and power of the shock somewhat as it works together. That is the only adjustment on the 1800.
A setting of 0 is the lowest and setting of 25 is the highest. As you move up in increments, the seat height does raise just a small amount , and also the suspension becomes more solid. .
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To answer your question, there is no height adjustment on the 1800 other than the rear suspension. If you set it at a lower preload it will be lower to the ground. The downside of this is that it makes it a bit harder to get on the centre stand.