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    Sonic Straight-Rate Fork Springs

    This spring, I bought a set of Sonic Fork Springs for my V-Strom in a rate appropriate for my weight (er, substantial) and riding style (um, sorta rapid).

    I was so pleased by the results that I immediately bought a set for my GS850. And then real life intervened for a few months in various depressing ways...

    Anyhoo, I finally got them installed in the GS850 last week, and have been mightily pleased with the results. Using the handy-dandy calculator on http://sonicsprings.com , I found that 1.1 kg/mm springs, the heaviest available, would be recommended for me.

    A measly $79.99 for the springs, plus $10 or $12 shipping, and I was in business.

    I bought these to replace a set of Progressive fork springs that have been suffering in my GS850's forks for 12 years. Progressives are great for the average bear, but they simply weren't enough for me. In order to get sag into the right place, I had to squash the snot outta the springs with monster preload spacers. It took an act of congress to get the fork caps on. I dreaded the old annual fork oil change, since I knew I would end up bruised and calling for my Momma.

    And in action, the Progressives worked OK, but since the spring rate wasn't up to snuff for me, brake dive was still excessive.

    The Sonic springs were a revelation. First off, they were sooooo easy to install. Now that I had the correct spring rate, I only needed 13-19mm of preload (1/2" to 3/4") to get sag in the right place (I used 17mm preload and sag was about 30mm -- just what I wanted.)

    On the first ride, the main thing that impressed me was the dramatic change in dive under braking.

    A few days later, I visited the twisties for a real workout. On the bumpy back roads, the fork was as smooth or smoother than ever -- no harshness whatsoever -- and braking confidence as well as handling under braking was much improved. On the smoother twisties, the bike's attitude under G-forces was improved as well -- instead of settling more in the front, the front end stayed in line and tracked quite nicely. Maneuvering midcorner was much easier, and the bike was more stable in cornering in general, with a bit of added ground clearance to boot.

    In the first few corners, the reduced dive under braking made the bike feel a tad slow-steering, but I got used to the change almost immediately.

    I'd say that if you weigh more than about 175 pounds and/or you're a faster rider, Sonic fork springs would be a definite upgrade over Progressive fork springs.

    If you're below that weight, I think faster riders would still prefer the more linear response of the straight rate Sonics, but the Progressives would still be a reasonable choice for street riders.

    Service is first-class -- the owner, Rich Desmond, is an avid rider and racer, and a GS1000 owner as well. If you don't see your bike in the application list, send Rich an email through the contact form, and he'll reply promptly.

    He has in stock (or can have made) fork springs for just about any application, although he might need the assistance of you or the forum to determine which is correct. (I'm always happy to help when I can find a supplier willing to provide parts for a vintage bike.)

    In my case, Rich originally sent 28mm OD springs for my 37mm OD forks. As it turns out, GS850 forks are a little thicker than GS1000 forks, so the fork ID is more like 27mm. He quickly had a set of 26mm springs made in the 1.1 kg/mm rate I needed and sent them to me at no added charge.

    A great experience all around, and the springs are a dramatic and worthwhile suspension upgrade. Highly recommended!

    Racetech also offers straight rate fork springs for vintage bikes, but they charge $10 more, and have very few vintage Suzukis in their application guide. I've also been very disappointed by Racetech's customer service -- they have never once returned my calls or answered my emails.
    1983 GS850G, Cosmos Blue.
    2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
    2015 Yamaha FJ-09, Magma Red Power Corrupts...
    Eat more venison.

    Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

    Celeriter equita, converteque saepe.

    SUPPORT THIS SITE! DONATE TODAY!

    Co-host of "The Riding Obsession" sport-touring motorcycling podcast at tro.bike!

    #2
    I have a set on my 850, i really like them, I had been off a bike for a few years and thought I just did not know how to ride any more. Put those springs in it was like a completely different bike. the handling is awesome.

    Comment


      #3
      Brian, what do you have in the back?
      Believe in truth. To abandon fact is to abandon freedom.

      Nature bats last.

      80 GS850G / 2010 Yamaha Majesty / 81 GS850G

      Comment


        #4
        Originally posted by dpep View Post
        Brian, what do you have in the back?
        Of the bike?

        Progressive 12 series shocks with 120/170 springs. These are one step heavier than the "heavy duty" listing for a GS850. They're actually only listed under the Kawasaki Voyager. With these, the preload adjusters are set at position #2 when I'm riding solo.

        After 12 years and nearly 90,000 miles, my Progressive shocks are getting a bit bouncy -- I really need to replace the shock bodies soon.

        We also put a set of these "extra-heavy-duty" springs on the Progressive shocks on George's GS1100E, and he's very pleased with the results. If you are over 200-220 pounds or so, you might need to do the same.

        There are five positions on the preload adjuster, and if you need to use anything but position #1 or #2 to achieve correct sag with just yourself on the bike, you need a heavier spring.

        My VX800 is also wearing Progressive 12 series shocks, but it weighs about 75 pounds less than the GS850. The heavy-duty Progressive shock springs work best on it.

        If I were starting fresh, I would spend a bit extra and get a set of Ikon shocks rather than the non-adjustable, non-rebuildable Progressives.
        1983 GS850G, Cosmos Blue.
        2005 KLR685, Aztec Pink - Turd II.3, the ReReReTurdening
        2015 Yamaha FJ-09, Magma Red Power Corrupts...
        Eat more venison.

        Please provide details. The GSR Hive Mind is nearly omniscient, but not yet clairvoyant.

        Celeriter equita, converteque saepe.

        SUPPORT THIS SITE! DONATE TODAY!

        Co-host of "The Riding Obsession" sport-touring motorcycling podcast at tro.bike!

        Comment


          #5
          I'm interested in using these shocks. Do you still need to add air to the forks with these?

          Comment


            #6
            forks need no air with sonic springs

            Comment


              #7
              sold! do they sell rear shocks? i couldn't seem to find them on the website. if not, what do you use?

              Comment

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