2007 crf250x sag
  • Jon Heron
    Posts: 2
    Joined: Thu Nov 19, 2015 4:31 pm

    2007 crf250x sag

    by Jon Heron » Thu Nov 19, 2015 4:37 pm

    Today I checked the sag on my new to me 2007 crf250x, here are my results.

    It appears the suspension is stock and has never been touched, the clickers were also all in the stock positions (according to the manual).

    It may be worth noting that first I bled the air out of the forks, I also noticed the right fork seal has been leaking slightly so I will change the seals and bushings this winter.

    On stand with back wheel off ground = 24.5"

    loaded without rider = 22.81"

    loaded with me and equipment (Without equipment I weight about 170)=20.6

    So this gives me, according to my calculating machine;

    race sag = 3.9"

    static = 2.2

    free = 1.69

    All of those look perfect according to the manual except for the free sag, the manual says this:

    6. Calculate the free sag dimension.
    To do this, subtract the loaded without rider
    dimension (step 5) from the unloaded
    dimension (step 2).
    Free sag indicates the distance your rear
    suspension should sag from the weight of the
    sprung portion of your CRF.
    With the spring pre-load set to obtain the
    proper race sag, the rear suspension should
    sag 0.4 to 1.0 in
    (10 to 25 mm).
    If the rear of your CRF sags less than 0.4 in
    (10 mm) from its own weight, the spring is
    too stiff for your weight. It is not compressed
    enough, even though you have the proper race
    sag adjustment. As a result, the rear
    suspension will not extend as far as it should.

    I am getting over 1", it does not say the effect of this though, do I need to be concerned with this?

    Any input would be appreciated.


  • mossman77
    Posts: 316
    Joined: Tue Jan 13, 2015 9:28 am

    by mossman77 » Fri Nov 20, 2015 6:24 am

    I'm not sure why the manual says 10mm to 25 mm for free sag. This conflicts with everything else I have read/heard. I believe 30-40mm is what you want to shoot for, with a race sag between 95-105mm.

    You're slightly over the 30-40mm guideline at 43mm, but your race sag is spot on. Since you're so close, I'd say one step softer would put you dead center. If you ride mostly trail, then you're probably fine as-is, but if you ride MX, you'll want to go with a softer spring. I realize this sounds backwards and I'll admit I continue to get confused after I haven't thought about it in a while.

    Put differently, if after setting your race sag, your free sag is too high, this means you had to back off on the preload to get the proper race sag, but you don't have enough preload to keep the bike elevated under its own weight. Therefore, your spring is too stiff. You can't simply increase the preload to bring the free sag where it should be because then your race sag number will be too low/stiff (because adding preload stiffens things up). The solution is a softer spring, which will allow you to increase the preload thereby allowing the bike to sit where it should, both loaded and unloaded.

    The opposite is true for a spring that is too soft. A soft spring will require a lot of preload to get your race sag set properly, but your free sag number will be very small. The solution is to get a slightly stiffer spring so you can decrease preload while maintaining the proper race sag and allowing the bike to sit where it should under its own weight.

    Good race sag, not enough free sag: Too much preload/spring too soft
    Good race sag, too much free sag: Too little preload/spring too stiff

    Clear as mud?

    This may help: http://www.dirtrider.com/features/under ... ension-sag
    2007 CRF250X
    2004 CRF230F (sold)
  • Jon Heron
    Posts: 2
    Joined: Thu Nov 19, 2015 4:31 pm

    by Jon Heron » Sat Nov 21, 2015 7:12 am

    Thank you for the detailed reply Mossman!
    I am used to bikes from the 70's where the only adjustment was spring pre-load... It's incredible how complicated suspension has become!
    The season is pretty much over here now so I think I will leave it as is for now and wait till I get more seat time and experience on the bike so I can better tell whats happening when I make adjustments.
    That and I will rebuild the front forks this winter, who knows how much oil has leaked out of that right fork with the leaky seal...

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