Harsh high speed bumps

Forums Mountain Bike Forum Harsh high speed bumps

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This topic contains 14 replies, has 5 voices, and was last updated by Profile photo of Franklin Dickinson Franklin Dickinson 2 years, 5 months ago.

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  • #214818

    Hello

    I am new to the forum and pretty new to mountain biking. I purchased a 2017 Giant  Trance 2 and like it. I weigh 205 pounds. I am running 205 pounds of air in the reach shock with 3 clicks of rebound reduction. My front shock has 75 pounds of pressure. I have tried running from three clicks of rebound reduction to neutral.

    Bumps like wash board roads or rough terrain with quick small high speed  bumps about rattle my teeth out of my head. The bike is fine on larger bumps.

    I have tubed tires and am riding on Knobby Nics. They say the least pressure is 32 psi  I was running 25 but ended with a flat.  I am now running 32.

    Is there anything I can do to soften these high speed small bumps and smooth the ride out?

    Thank you for your help

    and input.

    Franklin

  • #214819

    It’s hard to say not being present, but one thing to consider is how much of your shock travel you are using.  If it is very little, then you likely have too much air pressure in the shocks.

  • #214820

    Also how much of the rear shock travel are you allowing for sag?  Most riders allow for about 25-30%.  If you don’t understand sag, then just do a search online.

    • #215522

      Mongwolf

      i am running 30 plus of sag on the rear shock and still running about 220 pounds of pressure. That would include my 205 pounds and a ten pound backpack. On a moderate trail with bumps I use about 70plus percent of the travel. Would be less if I got of the seat more.

  • #214821

    Hi Mongwolf

    i have about 25-30% sag front and back.

  • #214822

    If the fork is brand new, it may take a few more rides to properly break in. Then you may notice it becomes more supple. Find a familiar trail with some washboard and play with the rebound setting. If you make small changes and ride the same section of trail you should be able to get er dialed. Also, you could try setting your sag to about 20% and see if it helps. Seems counter intuitive but it can make a difference.

    Cheers !!

  • #214826

    Thank you Bill, I will give it a try. I have had the bike about two months and have put about 150 miles on the bike. Both shocks are also left in the open position.

    Franklin

  • #214855

    On my Giant I run 20% sag front and 30% rear.. That seems to be about the best for me. But until you have a high end fork or shock level with separate high speed and low speed adjustments there is not a lot you can do.

  • #214926

    Maybe for your conditions you just need to run a little lower air pressure than normal in your shocks.  It can’t hurt to keep trying different pressures.

    • #215519

      Hi Mongwolf

      i have tried from 55 to 110. No real change in the high speed bumps.

  • #214928

    Also, you didn’t comment about how much travel you are blowing through on a typical ride.  So are you checking this?

    • #215520

      Mongwolfi

      At 55 pounds I used 5 inches of the 5.9 on a moderate trail. Sag appears to still only be 25% or so. I weigh 205.

  • #214954

    I’d argue you’ll get little change with suspension set up when it comes to high frequency small bumps at speed such as washboard or the like.

    The best suspension in the world simply doesn’t have time to react to this stuff when your speed is higher.

    The only thing you can do, imo, is use wider rims with tubeless tires and run less pressure.

     

    • #215523

      Thank you Zoso

      i was using 25 pounds in the tires though tire recommended no less than 32. After a blowout I now run 30.

      I think part of what you said I will do next, tubeless tires and much lower pressure. A buddy, only weighs 175, is running 20 pounds. He rides a Trek Fuel Carbon (without a doubt the nicest bike I have ridden). His is a Cadillac on the high frequency bumps.

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