Full suspension linkage comparison

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  • Full suspension linkage comparison
  • jk1980
    Member

    I remember a while back on here there was a link to some online content that provided a comparison between different linkage designs.

    Does anyone have that link please?

    Cheers

    Premier Icon Trekster
    Subscriber

    If you are “above average” wieght which system works best?

    “If you are “above average” wieght which system works best?”

    Assuming the frame and linkages are stiff enough, then one with as long a shock as possible for the travel (average leverage ratio closer to 2:1 than 3:1) and probably with a custom shock tune.

    jk1980
    Member

    Thank you,

    That’s not the one I remember, as I thought it was a spreadsheet, but nevertheless I’ve found the info I was after so thank you.

    Can someone please help me understand the linkage ratio / an issue for my bike? Just want to check I’ve understood it correctly. I have a 2018 Reign. The Reign historically, pre 2018, as I understand it, has always had quite a linear leverage ratio and has blown through its travel quite easily.

    Mine, the 2018 version, which I know they have made more progressive and I do find to have a very progressive curve based on what I can tell. Am i correct on the link below that because its curve is quite low down in the LR graph, that this means its a progressive design?

    http://linkagedesign.blogspot.com/2017/11/giant-reign-275-2018.html

    I guess if you calculate the average LR as 160mm / 62.5 = 2.56 is that considered to be progressive? If not maybe there is something up with my shock!

    kiksy
    Member

    Both the 2016 and 2018 Reigns have a progressive to linear to a smidge regressive curve.

    On that graph the Nomad 3 has a very progressive rate and the Turner a progressive to regressive.

    seanr
    Member

    To understand how progressive a linkage design is depends on the curve.

    Unfortunately its not as simple as your calc, as a fixed value would equal a linear ratio. The website you linked to is the best to identify what your bike is doing by looking at the linkage ratio.

    the00
    Member

    In this case ‘progressive’ is used to describe the change in leverage ratio acting on the spring & damper. Another term with the same meaning is ‘rising-rate’. On the scale of the graph that you have linked to, a liner rate will be flat, a rising rate (or progressive curve) will slope downward to the right through the travel, and a regressive rate will rise from left to right.

    What kiksy says is correct. The curve for your bike is over all progressive. It can be seen that the rate of progression is not linear (the line is not straight). It becomes less progressive, even flat, and then the very last bit starts going up (regressive).

    An air spring naturally has a progressive spring rate. To counteract this bike designs have moved away from progressive designs to a more linear rate. A progressive spring rate with a linear linkage will still result in a progressive rate overall. When combined with an air spring it is likely that your bike with remain progressive rate all the way through.

    If you want to make the spring rate more progressive, there are normally things you can do to tune the spring curve and the rate of progression (tokens for example).

    jk1980
    Member

    Thanks everyone, all really helpful.

    So am I correct then to interpret the leverage rate as progressive, but not overly progressive? I.e. if the curve starts high (3 in this case) does that mean the shock will move easily at first, moving through to the lower points on the curve, such as a value of 2ish, where the shock will meet more resistance in the linkage?

    If that’s the case then I think there’s something up with my shock tune, as the bike feels very progressive to me. I binned the basic coil due to lack of adjustments on the compression side and have replaced this with the EXT Storia. Luckily this is through Mojo who are good enough to re-tune for free if it’s not right.

    the00
    Member

    The linkage is just a lever. At zero travel it is a long lever, at full compression it is a shorter lever. From the graph the leverage ratio goes from about 3 to 2.4 . It is therefore 20% firmer. At half travel the ratio is around 2.5, so about 17% firmer. Sounds quite progressive to me.

    The linkage isn’t resisting the movement of the shock, the shock is resisting the movement of the linkage. The geometry of the linkage means that the resistance to movement imparted by the shock increases.

    I think the EXT shock has a hydraulic bottom out bumper for something like the last 20% of the stoke. Is this where you are noticing the resistance ramp up?

    kiksy
    Member

    does that mean the shock will move easily at first, moving through to the lower points on the curve, such as a value of 2ish, where the shock will meet more resistance in the linkage?

    From the chart the linkage is progressive until 120mm of travel, then fairly linear until 150 with the last 10mm being slightly regressive.

    The last 10mm being regressive is so that the natural progressiveness of an air shock is negated slightly, making it easier to use full travel.

    For a coil this can be less than ideal, but it’s only slightly regressive and doesn’t the Storia have adjustable bottom out support?

    In answer to:

    as the bike feels very progressive to me

    The chart shows this too, up until the last bit of travel.

    the00
    Member

    Just checked here:
    https://m.pinkbike.com/news/review-ext-storia-v3-shock.html
    The hydraulic bottom out acts on the last 15%, and increases damping by 50%.
    Unless you are hitting holes like Gee Atherton then I wouldn’t expect much movement in that zone!

    jk1980
    Member

    Thanks all, that makes sense now.

    The Storia does have a hydraulic bottom out but it’s unfortunately not adjustable. I don’t think that’s the problem though, landing off drops the shock feels amazing, you barely notice the landing. The problem is in general riding, the shock almost feels like it’s on lock out all the time, just very firm, despite playing with HSC/LSC.

    I was just wondering if it’s down to the inherent nature of the frame, as it was the same with the previous shock (super deluxe r), but I guess that can be tuned out hopefully.

    kiksy
    Member

    Obvious question but is spring rate correct?

    No preload on the spring?

    jk1980
    Member

    Spring rate I think is correct as I get 30% sag.

    Part of my reason for the question is that I’m just wondering if this is part of the inherent ride characteristic of the frame – as I said it felt pretty similar on the super deluxe R coil. Its fine for big hits but in general just feels pretty firm. Maybe if that’s the case then it can be tuned out by Mojo.

    I will also check the pivots although I’d be surprised if they needed attention as the frame was bought in Feb 2019.

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