ktm air suspension

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#1
I was wondering if anybody could explain to me how this new air suspension idea is supposed to work I know that the air is used in place of the spring is the shock just pressurized with more nitrogen than normal or is it more complicated than that I know there are some very intelligent people that use this site. Just curious
 
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#2
:silly: Don't believe everything you read in magazines......

I know what you're referring to and I have it from a very good source that there is no such thing being tested by KTM - at least, not anything from the suspension company that KTM currently owns.
 

HiG4s

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#3
This is right from the KTM website!!!

In the past, we used air forks on KTM’s (no fork springs!) and used very small air chambers, (around 40-45mm) with about 30 psi of static air pressure. Believe it or not, these ‘no spring’ forks could take the biggest hits and jumps without any problems.

Here is the link to the rest of the article.
http://www.ktmusa.com/ugvol11no1/ug16.htm
 

380EXCman

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#4
:(
 
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#5
Dear HiG, surfer and 380.....

Funny how things get switched around when taken out of context.

Notice that what Mr. Rosso actually wrote in his article are the words, "IN THE PAST we used air forks on KTM's".

The forks he is referring to were known as "Muller" air-forks. Yes, they could take any hit - but only once! The second hit was the one that blew all the seals out of the fork!

CURRENTLY, there is no such fork being tested by the factory, as was "reported" by one of the monthly off-road publications.

"OOpppss" :D
 

Jeremy Wilkey

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#6
Crow sure tastes bad dosent it! I never followed up on that..Did not even know, but was going man why would WP do that! I'm glad I did not have to entertain such thoughts..

:p
 

BrentBlain

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#7
i thought air in suspension was bad becuase it changes denisity with alititude. Wouldn't it handle different at sea level than like 8000 feet? That's just what i always thought but i am no expert.

-Brent
 
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#8
Do none of you remember FOX AIR SHOX, or are all of you that young?

Back in the late seventies it was very common to use FOX air shox in the rear and remove the fork springs and install air valves in the forks. We ran like very small air chambers in them too.

Guess what. It worked.

FOX air shox were a "must have" item for years. All the factory bikes had them. They were a dual air chamber shock.
 

MACE

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#9
Why do you think springs won't be replaced by air? Seems like a good way to lose 12 pounds.
 
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#10
Seals have come a long way in the past 20 years.

We use nitrogen cylinders to replace springs in the dies at work. The nitrogen cylinders look like a late 70`s FOX air shock with the mounting holes cut off each end of the shock. They hold 2000 psi of nitrogen with even higher pressures at full compression. They run tens of thousands of cycles before needing a rebuild that takes all of ten minutes to finish.
 
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#11
Seals weren't an issue 25 years ago, so I don't think the would be now.

We did it, it worked and we didn't even realize all the tuning options we had at the time.

I'm with Mace on the weight savings. I'd take a lot of Ti and CF to knock off 12lbs.
 

Jeremy Wilkey

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#12
The Fox shocked worked? At the time yes but.. The biggest hurdle I can see is one getting enough intial "preload" and yet not suffering from massive midstroke harshness. A spring is a linear, using a air spring would cause massive problems due to a masive pressure rise late in the stroke. Forks with 12 inches of travel with a high intial pressure (for static ride ht) would encounters some huge pressure..

A shock with a linkage ratio and reduced shaft travel would not be such a big problem as the total volume change would not be so large. An intresting concept but I need to see some ideas . concepts before I give up my springs.. How about we hot wind some fork springs.. That would do it.. We could reduce the amount of wire a good 20-30%..

Jer
 
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#13
Fox airshocks

I ran fox shox on my Maicos they had 2 chambers High preasure 137psi and low preasure 35 if can remember right.The big problem with those shocks was they topped out very harshly and when they got hot they got stiffer.They did work better than the Corta cosos that came on the bike.
 
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#14
Jer- That's because you are looking at the present suspensions physical constraints.

I'm afraid you're going to have to look outside the box on this one.

Fox was able to build a decent system with 70's technology. Someone should be able to build a better system with today's technology, but I would think it would require a dual pressure system like Fox used. KYB built a single pressure shock that did not work as well.

Bump absorption was the main focus back then.
 

MACE

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#15
If we have an infinitely large accumulator we get no pressure rise, right? It's all P1V1=P2V2, right? Whether or not you get a pressure spike is dependent on your initial and final chamber volumes.

Let's get stupid.... What if you had sealed damping cartridges separate from your spring air chambers. Now how about using steel sealing rings (like an engine piston) on your air springs with total loss high pressure source. What I mean by "total loss" is that you expect some blow by and you have to recharge your source about as often as you have to fill the gas tank. Let's use the frame for this gas reserviour. A pressure regulating valve maintains the fork spring pressure within a set range. The steel sealing rings are low friction and not prone to stiction under pressure.

If we are really stupid we also use our high pressure source to power our air shifter and our air driven starter motor.

Hey, I'll throw out 100 ideas and 99 are stupid. I'm still looking for number 100.