Also known as upside-down forks or USD for short.
On many sport bikes, the telescopic forks are inverted, with the spring/damper unit clamped to the yoke while the stanchions are at the bottom of the assembly. This is done for two reasons: to reduce unsprung weight by having the heavier components be suspended, and to improve the strength and rigidity of the assembly by having the bulkier and stronger component being directly supported by the pivot.
The disadvantage of the inverted design is that the entire reservoir of damping oil is stored directly over the slider seal such that, if the slider seal were to leak, the oil would drain out, reducing the effectiveness of the fork.
- Wilson, H. The Ultimate Motorcycle Book p. 181 Dorling-Kindersley Ltd. 1993 ISBN 0 7513 0043 8