USD (upside down forks) a.k.a. "inverted forks"

[Thumper]

What's the deal with USD forks??

Upside down forks (USD), or inverted forks add a modest amount to the cost of a motorcycle, but there are two main reasons why inverted forks are preferred by all racers and most bikers- Rigidity, and more agile/quicker response of the front end.

I stole this phrase from one of many articles that decribe the basic advantage of USD forks:

"they offer a more rigid set-up overall, which has a better capability of handling extreme stress during hard steering, braking, and other strenuous conditions"

How?
The body of the shock absorber is larger diameter (and stronger), and larger diameter triple clamps (stronger, more expensive) are required to attach them to the chassis at the headset. This makes the front end more rigid, which translates to better handling and better feedback for cornering, braking, and better control in all conditions, especially in the dirt.

Flexion of the front fork changes steering geometry, which can be felt by the rider (!), affecting steering/braking feedback, and rider confidence.

Unsprung weight of a USD fork is lighter. The stanchion connected to the axel is much lighter, which tranlsates to agile response in rough conditions (especially off road). They move faster, up AND DOWN to reconnect to the dirt. This translates into better control.

The combination of stiffer more responsive front end and less flexion combine for more confidence inspiring by providing more responsive control. So it is also a SAFETY thing. Imagine emergency braking in a curve when a car or deer crosses your path. This is where the USD engineering will help you even if you don't normally push your bike hard!

Disadvantages of upside down forks:
-oil leaks out quickly if the fork seal is compromised
-more expensive to fabricate/make, because of the beefier triple clamp needed

Budget bikes usually have conventional forks, and they are indistinguishable with the USD forks in most road use conditions. But you can get USD forks on a dirt bike like the Titan for an amazing price. Hawk DLX, Brozz and Recon (and Bashan Storm) are street legal, and they have USD as well. While it is hard to imagine a situation where less feedback, less precise control is desireable, if you do not plan on stressing the front end with hard riding, you may not need them. And cars almost never pull out in front of a motorcycle.

[Aussie_in_MO]

You forgot one major selling point/advantage... They look badass

[Aussie_in_MO]

Longer, skinny, traditional forks just don't do it for me.
Stock forks on my '79 XR500 were terrible. Flexed all over the place and made it more of a handful than it already was. Wound up swapping them out for forks and triple tree from a later model XR250 which were much beefier.

Had a similar experience with my '79 XS11 Special. Great in a straight line but really unpredictable and unstable when cornering.