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Conventionally, the fork stanchions are at the top, clamped to a triple tree, (aka "yoke"), and the sliders are at the bottom, attached to the front wheel spindle.
On some modern sport bikes, this system is inverted, with "sliders" (complete with the spring/damper unit) at the top, clamped to the yoke, while the stanchions are at the bottom . This is done (i) to reduce unsprung weight by having the lighter components suspended, and (ii) to improve the strength and rigidity of the assembly by having the strong large-diameter "sliders" clamped in the yokes. The inverted system is referred to as an upside-down fork, or "USD" for short.
A disadvantage of this USD design is that the entire reservoir of damping oil is above the slider seal so that, if the slider seal were to leak, the oil could drain out, rendering any damping ineffective.
Inverted forks are positioned on the motorcycle opposite or upside down when compared to conventional forks. The leverage forces that cause fork flex are greatest at the triple clamp area and weakest at the front axle. On inverted forks, the large outer tube of the fork is clamped in the bike’s triple clamps and the sliding inner tube holds the axle and front wheel. By locating the large diameter tubes in the triple clamp, the inverted or upside down fork have their largest and strongest parts combating the highest stress. This arrangement gives the forks high rigidity, which improves their response by reducing the side loading of the internal bushings (sliding surfaces). This kind of response is particularly important in high performance applications. Most inverted forks use cartridge-type damping systems.
Also, since the damping mechanisms are now held by the triple clamps, unsprung weight is minimized. Reducing unsprung weight is one of the biggest contributors to quality suspension performance, particularly for featherweight motorcycles like the YZ series or R1 and R6.
|There may be some unsprung weight difference (although you are replacing unsprung aluminum with unsprung steel), but the primary improvement is front-end rigidity. The smaller, more flexible, inner tubes are 3 - 4 times as long on "conventional" forks as "upside-down" forks. The triple clamps gripping much larger diameter tubes also makes a really big difference in rigidity there. Those two things combined result in upside-down fork and triple-clamp assemblies being WAY more rigid. That's why the first place they became popular was in Supercross, where they were far better at handling the stresses of the giant jumps.|
So in conclusion, it looks like inverted forks provide better performance (more rigid, less sprung weight, etc.) but at cost of bit more maintenance (no easy fork oil drain it seems like on a standard fork)
I like them, mainly for looks. Standard forks just look REALLY outdated compared to them.
|But this also comes with a MUCH higher chance of getting a knick in the slider from road debris, and a significantly harder rebuild process.|
|I do wear a helmet, as a matter of fact, along with other protective gear. But, the fact that you “certainly hope” I wear a helmet is so condescending it makes me want to ride a tricycle completely naked doing doughnuts in your front yard screaming Beastie Boys lyrics at midnight. Trust me, you do not want that. My buttocks are extremely pale and unsightly, especially in moonlight.|
I dunno. I had GSXR forks on my first gen SV650 and they were tits.
You can't really compare shitty damping rod, undersized, standard forks with shitty twin piston calipers to inverted, cartridge damper, larger diameter forks with radial four piston calipers.
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|Thread||Thread Starter||Forum||Replies||Last Post|
|Has anyone changed front forks to inverted forks||Racer78||ZZR-600||5||05-02-2008 10:18 AM|
|Inverted forks?||EricKC||YZF-R1||2||09-18-2004 06:05 PM|
|Inverted Forks||TXF4i||General Sportbikes||3||07-23-2002 05:01 PM|
|Inverted Forks||Sbninja||General Sportbikes||5||06-11-2002 09:17 PM|