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Thread: Linkage or PDS.

  1. #1
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    Linkage or PDS.

    I've said here before that I know very little about the PDS system, so aside from marketing reasons I'm looking for somebody to convince me why it is necessary and why some class it as the future for suspension.
    The case for linkages:
    short shocks can be used making them lighter.
    the shock can be positioned close to the bikes centre of gravity.
    they can have infinately variable motion ratio's with respect to wheel travel.
    a linkage changes the rate of velocity as well as spring force.
    the shock compresses in a straight line with very little rocking motion.
    Is a complex link and simple shock the way forward or a complex shock and no link?







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    No point in asking as the PDS will be dropped in 05, the linkage KTM has been seen testing.




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    Is that it then consigned to history, or are Husaberg going to continue development?




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    Quote:
    No point in asking as the PDS will be dropped in 05, the linkage KTM has been seen testing.

    Marcus,
    I'm surprised at your reply, you may or may not be correct about KTM going back to linkage, but the question still raises a valid point.
    I for one think the non-linkage system has got a bad rap. I have ridden/owned (many) bikes with and with out linkage. I have a 02 KTM and will admit it tooks some tuning to get it right, I am very satisfied with the rear suspension. If I had any complaints about the suspension on my KTM it would be that the forks are to flexible.
    I also had a chance to ride one of the late model Cannondales and I would have to say it had the best suspension of any bike I have ridden, it also sports a non-linkage rear suspension with a Ohlins shock.
    What areas do think the non-linkage suspension are weak in?
    I will admit that I'm no motocrosser, so there might be some valid points of the non-linkage vs. linkage that I wouldn't consider.
    Happy Holidays,
    Dave Thoms




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    As i've said before the PDS system was one of the greatest marketing exercises we've seen in the motorcycle industry. It has advanced KTM into the mainstream of motorcycle manufacturing. I'm not surprised to hear that KTM are now leaving the linkless system behind for more conventional methods. They have achieved a level of credibility akin to that of the Japanese manufacturers and can now set about beating them at their own game. Last time I spoke on the subject of position sensitve damping I managed to raise the ire of one Jeremy Wilkey and my knowledge of the subject was severely questioned. Well, I would just like to say that position sensitive damping does not exsist within the confines of this design, and at best, we can only experience a positional influence from the PDS system. And given the design of the linkage assisted shocks we also experience a positional influence, only over the full travel, and with a nice progressive nature. The PDS system has seen both manufacturers and aftermarket tuners struggling to compensate for the lack of a linkage, falling short all the while. The truly sad thing is that they are getting closer all the time. The simplicity of the linkage system is spectacular when you consider the comlexity of trying to do without it. Now that things are calm Jeremy I'll happily answer any question you have for me regarding my views on the PDS shocks.
    Regards
    Terry Hay -- MERRY CHRISTMAS!!!




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    What I'm really trying to nail is why was it conceived, I can't believe it was conceived with no technical merit, what were the perceived advantages over a link, you could never argue it was less complex.
    You remove one maintenance task in that there is no linkage to clean and grease but apart from that I can only see disadvantages.
    Can a progressive spring be wound to give an accurate rate of progression?
    What were the thoughts on damping requirements that led to a twin piston design?




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    dave yes my reply was lacking to be honest , as usually i love to talk for hours about all suspension stuff.Sorry about that svi , i was just trying to put out some info and did it badly.

    Well IMO the linkage-less design has merits and shortcomings, in theory its lighter(but a CR weighs less than a KTM) and has less stiction(well if it wasnt for the 2 piston rings and big 18mm shaft it might have less)is easier to service (hmm not IMO due to the complex pds internal design)and the bottom bearing requires no maintenance(well it would if it lasted 2 seasons LOL)
    So what are we left with?, well it is easy to remove and replace.

    I believe the pds can work for woods stuff, but mx and sx is its downfall IMO.Now saying that the later ones are actually not too bad and feel IMO more like a normal bike.

    So back to a linkage bike-its more tunable and easier to tune IMO.Its got a harder to service linkage and its more costly to service.However it crosses over the different terrians better IMO.I think a good chassis dyno could have got the PDS working alot better than i does.

    Overall i will take a linkage bike just because i believe they are ultimatly better.




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    No point in asking as the PDS will be dropped in 05, the linkage KTM has been seen testing.
    Yamaha has been testing a aluminum chassis now for quite a few years but its still unclear when or if they will put it into production.

    Some PDS positives.

    Shock can be offset allowing for a more direct intake track = more hp.
    Lack of linkage = less weight.
    Lack of linkage = less maintinance.

    I think that the PDS represnts the cutting edge in suspension technology. They have come along ways since 98. I think what they have now "04" is as good as the Japanese equipment. Maybe the PDS just needs more time to develop. But to scrap the whole deal at this point would be just going backwards. They currently sell every bike they make, so its not as if the PDS is holding the bike back so much that no one is riding them. Also look at how successful they are in competition, The PDS does not seem to hold them back to much there either......



    m y   s i g n a t u r e:


    Save our children, club a politician!


    Previous Bikes,02 380EXC, 04 525SX, 02 380SX, 01 FC550, 99 380EXC, 98 DR350

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    svi as far as i know one big shortcoming was the progressive springs were all testing too much away from specified-so you need to get maybe 3, to actually find one that is as you expect.




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    I believe the pds can work for woods stuff, but mx and sx is its downfall IMO.
    Im not so sure of that. The vairiables incountered in off road is much greater than on a MX or SX track. In the desert where I do most my riding you can go from hard pack to sandwashes to whoops so big a volkswagon will sit upside down in, to rocky sections and all at speeds ranging from 5 mph to 85 mph.....
    As i've said before the PDS system was one of the greatest marketing exercises we've seen in the motorcycle industry. It has advanced KTM into the mainstream of motorcycle manufacturing.
    I think what has made KTM so successful is their vision and their commitmnet to dirt bikes (not drums, keyboards, lawn mowers, cars, etc, etc). The quality of componets, like the hydro clutch, plated pipe, chromoly frame, qualtiy bars and chain, no tools air filter access. I think this is what has made KTM what they are today. Not to mention offering a competitive alternative to the japanese MFG's...




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