Race sag:effect on cornering??

Discussion in 'Dirt Bike Suspension' started by kawraper, Apr 7, 2009.

  1. kawraper

    kawraper Pro Class
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    Just wondering how would too much/not enough race sag effect cornering. I know Ive got too much right now just havent gotten around to resetting it yet. Im a little guy 5'7"-5'8" 130lbs geared up. I was messing with tire pressures and found when I ran on the low side it made a huge difference in railing sandy berms but was wondering if the sag was also a factor.

    The bike rides great on whoops, doesnt bottom on jumps so im hesitant to change it. But if I get a response that proper sag will make it corner better ill get on the adjustment.
     
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  2. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    Leave the tire pressure work to nascar guys. Your manual says 15, 15 it is. You are trying to get it to corner? The same people who came up with the 15 psi in the tires, tell you to run the sag at 4 inches. Smoother tracks run more ,and the rougher gets less sag. After you get your 4 inches of race sag, check the static sag. I am sure you will need softer springs.
     
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  3. IndyMX

    IndyMX Crash Test Dummy

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    Huh.. I like my pressure around 13 psi..
     
  4. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    Let me guess, the ex bridgestone guy? Tube pincher! A couple pounds probably would not hurt? The tire and the book usually tell you 15 psi. It helps the tire from spinning and pinching. the rest is form and set up. And fear! Springs and sag, then fiddle with the clickers. It will corner, its up to the rider.
     
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  5. SpDyKen

    SpDyKen Lifetime Sponsor

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    I alter my tire pressure based on conditions. I would only run my tire pressure as high as 15 psi. in rocky, or high-speed hard-pack conditions.

    It is my perception that many off-road racers do the same. I think pro MXer's do, also, but rely on the tire mfgrs. to provide them the proper pressures for each track & conditions.

    As a former road racer, I varied tire pressure to affect traction and wear, all of the time, but used the tire maker's recommendations to start.

    I'm pretty sure that that dirt-trackers alter their pressures, as well.

    I can tell the difference in 1 to 2 psi., when I am riding. Different tire & tube combinations require different pressures, also, IMHO.

    Your suspension sag greatly impacts your bike's steering. This is why the factory teams spend so much time testing. There are many, many, variables that need to be tested, in conjunction with each other. :nod:
     
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  6. kawraper

    kawraper Pro Class
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    So did I read anywhere how too much/not enough sag will affect cornering?
     
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  7. James

    James Lifetime Sponsor

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    I read where you mentioned tire pressure first :)

    Sag will affect cornering. Too much slows the steering, too little steepens the steering. Both affect the way your suspension reacts. You will have to experiement to find out whether you corner better with more/less sag.
     
  8. Papakeith

    Papakeith COTT Champ Emeritus
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    I ride almost exclusively in roots and square edged rocks and sometimes run as low as 10 lbs. no pinch flats yet.
     
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  9. adam728

    adam728 Pro Champ
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    I'm with SpDyKen 100% on his tire pressure views.

    If you don't have enough sag the bike can become twitchy and unstable. It can even cause headshake. Too little sag and you'll be pushing in corners.

    Proper sag is very important in overall suspension performance as well. Some guys claim they can feel a 1-2mm change. I'm not that good, but I keep my sag right around 102mm all the time. I don't change sag for conditions, only the compression/rebound settings.

    The only time you should really change sag is riding mud, where the extra weight of the mud will effect the sag. Otherwise pick a number and stay with it.
     
  10. whenfoxforks-ruled

    whenfoxforks-ruled Old MX Racer

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    Ken is right on, for trails and what not. Kawraper sure did not specify. Specify what you are intending on riding , before the trials guys get on this! But I took it at MX racing, 13 to 15 is good. Trails are a lot different than a nicely groomed MX track. Set the bike up as called for in the manual, its a very good baseline. Learn to ride it, then see if it is pushing the front end, or knifing. And do not go with too much sag that you are bottoming a lot on jumps and what not. The more sag the better it will set in the corner and power out! You get fast enough and bottoming in the corner starts happening. When you get that fast, you will see why new tires are appreciated every week. Sell the old ones to the trail guys? 4 inches outdoors and 3 3/4 for sx.
     
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