What fork settings for heavier wheels??

likewoah
likewoah Posts: 78
edited June 2009 in MTB workshop & tech
If I put on my DH tyres I'm adding about nearly 1kg per wheel.
Should I increase the rebound? Or decrease the rebound?

Comments

  • bomberesque
    bomberesque Posts: 1,701
    I've never thought about it tbh. General advice seems to be have the rebound as light as you can without it jacking back up at you.

    I suggest a short ride round the local woods to see if or how much difference it makes. I'm tempted to say "none" but I don't honestly know
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  • nicklouse
    nicklouse Posts: 50,673
    do nothing.

    if you are adding 1 kg over your current set up they bike is not suitable for the tyres.
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  • dave_hill
    dave_hill Posts: 3,877
    likewoah wrote:
    If I put on my DH tyres I'm adding about nearly 1kg per wheel.

    How do you reckon that up? DH tyres don't weigh a 1kg more than normal tyres!!??? Maybe about 1.2kg each...

    In any case, it's unsprung weight so you don't need to make any adjustments.

    Nick, just out of curiosity how do you know that the OP's bike isn't suitable for DH tyres?
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  • nicklouse
    nicklouse Posts: 50,673
    dave_hill
    I dont. :cry:

    but the question reads as XC to DH rather than FR to DH where the difference would be a few 100 grams per tyre and maybe a bit for tubes ( all depending on tubes/tubeless and make of tyre)

    also If you were going to be changing to DH tyres i would hazard a guess the terrain is changing and that would actually make a bigger change on fork/shock settings that the change of tyres.

    Unsprung weight is important but not that important as say in this case the gyro effect of the extra weight.
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  • Mike Deere
    Mike Deere Posts: 4,259
    Dave's got it right.

    It's unsprung mass, it won't make a difference to your suspension setup.
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  • nicklouse
    nicklouse Posts: 50,673
    mike not 100% correct as it IS the damping that controls the wheel movement not the bike movement.
    They do both (wheel and bike movement) have an effect on the feel of the bike.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
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  • likewoah
    likewoah Posts: 78
    Went from a XC nevegal (600g) to a DH Blue groove (1450g)...ok a bit under 1kg :)
    So if you pull up the handlebars, you can feel the wheel dropping away quicker. I assumed then you would slow the rebound to make the wheel fall away the same as before.
    But as you say it is unsprung mass. That makes no difference then?
  • nicklouse
    nicklouse Posts: 50,673
    my i ask why?

    really a change in compression would be needed as well.

    BUT if you are changing for rougher terrain you have other things that will require more thought on the settings.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • supersonic
    supersonic Posts: 82,708
    An easy way to look at this is the energy stored in the spring: the rate of a fork spring may be 50kg per inch which is returned as a force when rebounding and damped.

    Soa few 100g will make little difference to rebound!
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  • likewoah
    likewoah Posts: 78
    NOw that I understand! It's a pretty small amount compared to the rider.
    I was doing uplift days BTW. Very glad for having the tougher rubber
  • supersonic
    supersonic Posts: 82,708
    Aye, tougher rubber is useful in many areas ;-)
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  • nicklouse
    nicklouse Posts: 50,673
    likewoah wrote:
    NOw that I understand! It's a pretty small amount compared to the rider.
    I was doing uplift days BTW. Very glad for having the tougher rubber

    so a bit more DH riding. that would require more of a sus setting change than the tyre change.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • Rockhopper
    Rockhopper Posts: 503
    I'm more familiar with motorbike suspension but i guess the principles are the same. If you make big changes to your unsprung weight then the compression/rebound adjustsments are not what you need to fiddle with, you actually need to change the damping rates inside the forks or shock. This is fairly specialised work but i would have though TF tuned could do it.

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