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Thread: Suspension Sag question

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    Suspension Sag question

    Hi all, unfortunately I知 one of those guys that their first post is asking for help, but I知 glad to be here and have enjoyed reading/researching so far

    I have recently bought a 2008 CBR600rr track bike, have never owned a trackbike and will be doing my first trackday soon, which means I have a few questions that I have researched but need further advice, the main question is around Sag setup - I know this has probably been covered a million times and have searched but couldnt find this issue, however happy to be pointed in the right direction


    As it痴 a trackbike, I believe I should be aiming for around 25-30mm of rider sag. I知 currently getting around 25mm on the front, but only 16-18mm at the rear with pre-loud wound right back (softest). Its running 1.1kg front springs (not sure what on rear), Racetec website suggests 0.95kg for my weight (80kgs). I'm expecting to be told i need to replace the rear spring with a softer one to get the Sag values to match, its on my 奏o do list, but wondered ift he front/rear bias currently on the bike is a major concern for a level 1 rider?
    Whats the likely impacts of running this setup and what adjustments can I do to lessen the affect.

    Cheers

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    Member Marc78's Avatar
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    Hi TopperS15, I have no idea about suspension setup so I am watching this thread with interest. I will probably go to a professional (as will be the general advice) but its nice to know the theory.

    Only thing I thought with rear sag, is to have a feel by lifting the rear seat/frame with the bike in the up right position. At full stiff preload, the seat will not lift, at full soft, the seat will lift quite a bit. So when the bike is on the side stand and you move it to the upright position, you will feel the bike squat which is the unloaded rear sag. So if you've set your rear sag to softest then I thought you would have more sag, not less?

    I'm 90kg so I actually adjusted my rear sag last night because the bike felt like it would squat too much under acceleration and also felt too low relative to the front. So I went more stiff and bike feels more quick to go rather than squatting down then going.

    As I said, I could be completely wrong and happy to be corrected.
    Quote Originally Posted by TopperS15 View Post
    Hi all, unfortunately I知 one of those guys that their first post is asking for help, but I知 glad to be here and have enjoyed reading/researching so far

    I have recently bought a 2008 CBR600rr track bike, have never owned a trackbike and will be doing my first trackday soon, which means I have a few questions that I have researched but need further advice, the main question is around Sag setup - I know this has probably been covered a million times and have searched but couldnt find this issue, however happy to be pointed in the right direction


    As it痴 a trackbike, I believe I should be aiming for around 25-30mm of rider sag. I知 currently getting around 25mm on the front, but only 16-18mm at the rear with pre-loud wound right back (softest). Its running 1.1kg front springs (not sure what on rear), Racetec website suggests 0.95kg for my weight (80kgs). I'm expecting to be told i need to replace the rear spring with a softer one to get the Sag values to match, its on my 奏o do list, but wondered ift he front/rear bias currently on the bike is a major concern for a level 1 rider?
    Whats the likely impacts of running this setup and what adjustments can I do to lessen the affect.

    Cheers
    Last edited by Marc78; 20-09-2016 at 09:41 AM.
    擢ear keeps us alive. Never, not be afraid. - Grug Crood.

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    Quote Originally Posted by Marc78 View Post
    I also like the extra few mill of ride height and distance to the pegs.
    The distance between seat and pegs will not change by adding preload or ride height...

    They are both attached to the same solid frame...
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    Correct

    Yesterday I wore winter trousers, today jeans, that was the difference ha ha.

    But pretty happy that the rest of my understanding about sag was not incorrect?

    Quote Originally Posted by Rich... View Post
    The distance between seat and pegs will not change by adding preload or ride height...

    They are both attached to the same solid frame...
    擢ear keeps us alive. Never, not be afraid. - Grug Crood.

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    1st thing welcome to PSB, second, what Potato said, third thing is did you do the measurement with all your track riding gear on?
    I cant help it if your perceptions don't match my reality



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    Following with interest too, coincidentally I was recommended to talk to martymoose to set my bike up properly for me....it made night & day difference for a good mate on the track!

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    Quote Originally Posted by TopperS15 View Post
    but wondered ift he front/rear bias currently on the bike is a major concern for a level 1 rider?
    Hey dude. I was in your position when I did my first track day last year. I was worried about every little detail being perfect, and was over-thinking a lot of things. A track day is basically just rider training in a controlled environment. The goal isn't to push yourself as hard as you can, or you'll probably crash. You can complete Level / Group 3 track days on a road bike with road suspension settings and tyres if you so choose to. There are loads of businesses in Perth that can 'set up' your suspension for you, but it's up to you to experiment with it and decide what feels right for you. For a level 1 track day, I wouldn't bother seeing as you'll probably spend most of it in 3rd/4th gear with no brakes..

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    Thanks all for comments.

    Quote Originally Posted by Ryanoceros View Post
    Hey dude. I was in your position when I did my first track day last year. I was worried about every little detail being perfect, and was over-thinking a lot of things. A track day is basically just rider training in a controlled environment. The goal isn't to push yourself as hard as you can, or you'll probably crash. You can complete Level / Group 3 track days on a road bike with road suspension settings and tyres if you so choose to. There are loads of businesses in Perth that can 'set up' your suspension for you, but it's up to you to experiment with it and decide what feels right for you. For a level 1 track day, I wouldn't bother seeing as you'll probably spend most of it in 3rd/4th gear with no brakes..
    I was thinking along these lines, just to see how she felt and then go from there, my concern is the sag bias and if that may create any problems for me with stability, even at Level 1. I understand a road bike can be used with stock settings, but would presume the sag would be set correctly front and rear.

  11. #11
    Member SomeBloke's Avatar
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    Quick FYI. Turn 7 is the hardest braking point in Australia. If you run what Racetech specify, it is possible when you improve that you will run out of travel with the front forks. The bike sounds like it may have been set up for racing already (since it has a 1.1 and OEM is 1.0).

    I would recommend that you leave it as is until you have had a few more sessions on the bike, get the coaches advice when you do a trackday and they will be able to point you in the right direction. As for baseline setup, the best thing IMO would be to have a racer/coach ride it for a lap or two, they will quickly be able to tell you if the set-up is blatantly wrong or not.

    I have coached on my road R6 before, standard suspension, road tyres and in all probability a "wrong setup". It still handles well enough to easily exceed group 2 pace.
    "Life begins at the end of your comfort zone."

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    Agreed, will give her a go and see how it feels.

    Whats the impact of the rear being too stiff, loss of grip?

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    The springs are too hard you are not going to achieve correct sags with them. Its one of those issues that is either right or wrong and they are just plain wrong for you.

    MM
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    Quote Originally Posted by Marc78 View Post
    I also like the extra few mill of ride height and distance to the pegs
    You want adjustable rearsets. Along with suspension, one of the best mods you could ever do if the stockers don't work for you.

  15. #15
    Member Marc78's Avatar
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    Quote Originally Posted by Kristy View Post
    You want adjustable rearsets. Along with suspension, one of the best mods you could ever do if the stockers don't work for you.
    I also want rear sets because I completely destroyed the paint coat on the stock heel guards within a week. That is their purpose, but I've never worn out the heel guards on another bike. Ended up covering the heel guards in Suzuki carbon look sticker/pads that they brought out straight away after realising how sh*t the heel guards are.

    The bike feels more spacious since adjusting the rear sag, maybe its a placebo effect or maybe it is the ride height and seat relative to bar angle. Also (now I'm not sure strictly this is a good thing in suspension language) but the front end is coming up a bit quicker and the TC doesn't like it ha ha.

    I plan on contacting MM for a set up in the near future. Rearsets are on the list, but so is a quick shifter and maybe a slip on.
    擢ear keeps us alive. Never, not be afraid. - Grug Crood.
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    Quote Originally Posted by Marty MOOSE View Post
    The springs are too hard you are not going to achieve correct sags with them. Its one of those issues that is either right or wrong and they are just plain wrong for you.

    MM
    Agreed, rear spring is too hard and probably needs changing, just wondered the impacts of not changing it and running a lower sag measurement at the rear vs front.

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