Stupid question (not to worry Ray23, you are not alone)

Discussion in 'General Discussion / News / Information' started by tonykiwi, Nov 12, 2008.

  1. tonykiwi

    tonykiwi Ol'Timer


    Can someone tell me the relevence of the upside down forks. I own a Baja and my forks are the other way up (1998) so am looking for simple explaination why upside down forks make a difference.

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  3. KZ

    KZ Ol'Timer

    Unsprung weight - especially on a dirt bike it's important to have a light and easy to maneuverable front end. Any weight below the springs is unsprung weight; conventional forks have the heavy fork legs on the bottom, adding weight to the unsprung wheel. Turn it upside down and the fork legs are above the springs = sprung weight which makes the front end lighter.
  4. tonykiwi

    tonykiwi Ol'Timer

    Thanks heaps, perfectly explained.

    So, why is this such a recent innovation. Physics is a pretty old science. Is it a change in riding style or a new discovery in motorcycle production that has brought this about
  5. KZ

    KZ Ol'Timer

    Often there's the question after a discovery or after an invention: Why haven't we thought of that earlier? Sometimes all the required parts exist to make a groundbreaking improvement, it just takes a brain that puts the things together and makes it work. For example hybrid engines - for decades we've been using a gasoline power plant to make a vehicle go, and used brakes to slow it down. Someone should have realized decades ago that squeezing pads to metal isn't the smartest way to go, producing friction and heat but no usable energy. Use dynamos instead to slow the vehicle down and produce electricity, so you won't need a belt-driven generator which sucks energy from the engine.
    Tha Japanese are selling hybrids by the shipload and the Americans and even the Germans have missed the boat.
    Sometimes it's just a matter of putting existing things together in a sensible way nobody ever has thought of, and it may be an invention that helps to keep our planet cleaner and even make you a millionaire!
    It just takes an inquiring and critical mind. Ask yourself: Why is this working the way it works? Can it be improved? And how?
    Often the process starts when you say: I don't like this. This is stupid. Why did they make it work like this? If you complain, there's room for improvement. Your chance to improve it!
    A simple worker at Volkswagen won a price for his idea. He asked himself why a car has to have an ignition key, a door key, a trunk key, a gas cap key and maybe even a key for the glove box. Why not make one key for all locks? Save the owner time and the company money!
    When Howard Hughes was hospitalized after one of his plane crashes, he designed a better hospital bed because he wasn't happy with the one he was in. Because he had an inquiring and critical mind. The nurses who pushed around these beds every day didn't. The patients in them didn't.
    'Physics is an old science' - yes, and it is brand new every day. And there are hundreds of improvements all over the world every day. It's just up to us to think outside the box, challenge existing processes, and come up with a solution to a problem which others haven't even recognized as one yet.
    Who invented the zipper?
  6. tonykiwi

    tonykiwi Ol'Timer

    Funny you should ask because I have had more than one tearful moment in my life when I have asked the same question.

    I think back to my very first offroad motorcycle. Was a Greeves 250 with that weird front suspension that had the large swinging arm around the wheel. Don't ask me what it was called, I am going back to late 60's.

    Thanks for your reply, make for interesting reading.

  7. cdrw

    cdrw Ol'Timer

    Surely Ray is not alone...this is a topic that still has me confused.

    I going to sell my wonderful 250 Djebel and want to get a Suzuki DRZ400, however the fork issue still has me confused.
    The DRZ400 S and E models, which are both off-road bikes, both have conventional forks, whereas the SM model which is road vehicle has the USD forks.

    The only real differences between the S & E models and the SM is the SM has 17" wheels, the USD fork, and a slightly larger front brake disc.

    SO, if the USD front fork is superior...even in the dirt...would it be best to get an SM for the road and a spare set of 18"/21" wheels and tires for dirt which just use the slightly larger SM brake disc??
  8. KZ

    KZ Ol'Timer

    I wrote that less unsprung weight makes the front end 'lighter', which is not correct, I meant 'easier to handle' - the weight remains the same, just the unsprung weight is a bit less. Upside down forks is the smarter way to go , but it doesn't make a hell of a difference. If you're an off-road ace riding competitions, you would feel the difference, but I doubt that it would effect an average rider any.
    I wouldn't get a SM just for the cooler looking fork if I'm seriously into off-road riding.
  9. monsterman

    monsterman Ol'Timer

    Upside downers tend also to be stiffer and lighter so 2 more benefits.
  10. KZ

    KZ Ol'Timer

    Would upside down forks be more stiff than conventional ones with the same diameter and specs?
  11. monsterman

    monsterman Ol'Timer

  12. roaddhist

    roaddhist Ol'Timer

    Hope this isn't too far off the subject but, speaking of front ends, in my BMW riding days back in the 'States, a common upgrade was the lower fork brace which kept the lower fork tubes from shifting under stress. There's a light duty one on the road bikes with fenders over the wheels but the dirt bikes with the fenders mounted high leave a great distance between the fork tube mounts and the axle. One would think, with the increased stresses on the front wheel in off-road use, that a fork brace would be standard equipment but I have never seen one on a dirt bike here or elsewhere or even an after-market option. Does anyone reading this post know if one is available and where or should I create a new post to get more input? This upgrade should improve handling in off-road use.

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