What's the advantage of upside-down forks?

mstevens · May 09, 2008, 05:30:52 PM

Clearly, I'm no technical whiz! I've tried searching the web, but all I can find is descriptions of upside-down forks but nothing about what makes them better.

So, what's the deal with them?

Speeddog · May 09, 2008, 05:43:31 PM

Stiffer, stronger.

When they were originally developed for MX, it was the only way to get sufficient travel (12") and still have enough overlap between the tube and slider for stiffness, yet not have a whole bunch of fork stuff hanging below the axle.

ScottRNelson · May 09, 2008, 05:43:55 PM

The biggest advantage is that they're way stiffer than the other kind. You used to always see motorcycles with fork braces that held the bottom tubes in place so that the forks couldn't flop around so much. That is not needed with the upside-down or male slider fork. You also have a little bit less weight moving up and down along with the front wheel.

The extra stiffness is a big improvement over the way things used to be. That and radial tires produces much better handing motorcycles now.

stopintime · May 09, 2008, 05:45:32 PM

I think the correct term is "less unsprung weight" (forreigner

). The wheel will move easier up and down without also moving the weight of the damper/suspension. This makes for better/more even contact with the ground = safer ride. Feel free to correct me if I'm off

mstevens · May 09, 2008, 06:35:06 PM

Thanks!

So, stiffer and less unsprung weight. Got it.

mitt · May 10, 2008, 11:57:55 AM

The easiest way to see why they are stiffer is that all the bending stress is up by the triple clamps. There is no bending stress near the axle. So, upside down forks but the largest cross section (largest diameter) up in the bending stress area.

mitt

Alex · May 10, 2008, 01:02:32 PM

Quote from: mitt on May 10, 2008, 11:57:55 AM
The easiest way to see why they are stiffer is that all the bending stress is up by the triple clamps. There is no bending stress near the axle. So, upside down forks but the largest cross section (largest diameter) up in the bending stress area.
mitt

Cool, I'd never thought of that part.

hypurone · May 10, 2008, 03:04:34 PM

And they are SO purty too!!

teddy037.2 · May 11, 2008, 06:17:52 PM

cool beans! I was just talking about this w/a buddy of mine today on a ride...

we both had no idea...

Lord_Bragle · May 12, 2008, 05:20:47 AM

Human legs are a bit like upside down forks I always think, slender components in the lower sections like ankle joints and shins bones and thiker (thighes) and with much stringer joints (knees and hips) in the upper areas, less knee knock proly equates to less fork flex lol, what do I know

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What's the advantage of upside-down forks?

teddy037.2