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Old 08-30-2007, 09:04 PM   #1
convict231688
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when i roll out of the throttle my bike dives. it really throws me forward. i adjusted the front shocks and dont want to tighten them much more and like the lift on the tail, but should i tighten up the rear suspension to keep it fron diving forward???????????
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Old 08-30-2007, 10:19 PM   #2
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Thats wierd....when i roll on my throttle my bike gets lite in the front...are you sure you aren't brakeing ???JK...maybe someone else can figure it out.
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Old 08-30-2007, 10:42 PM   #3
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Quote:
Originally Posted by downshift View Post
Thats wierd....when i roll on my throttle my bike gets lite in the front...are you sure you aren't brakeing ???JK...maybe someone else can figure it out.
He said roll out of the throttle or letting off.
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Old 08-30-2007, 10:51 PM   #4
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whoops...I just got done reading 5 hours of biochemistry lol...My eyes hurt
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Old 08-30-2007, 11:12 PM   #5
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Have you set the proper sag for your bike? That should fix most of your problem correctly if your springs arent set proper.
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Old 08-31-2007, 02:02 AM   #6
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The front shouldn't dive as you call it. The entire bike should kinda squat but that's when you are off the throttle and on the brakes.
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Old 08-31-2007, 02:57 AM   #7
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You need to set up your bike's suspension & the spring preload aspect of this depends on your weight. I did a write up on this for another website & here is a copy & paste of that piece:

PART ONE - SETTING RIDER'S SAG
First you need to set your bike’s riders sag front & rear. Get all your riding gear on & get a buddy to help you make measurements. You need to completely unload the suspension you are working on in order to find out how much suspension travel your bike has. On the front end you can use a front end stand or a strategically placed floor jack under the engine. If you go the floor jack method be careful & find a good, save balance point & jack it up slowly & don’t go that high up. To measure the suspension travel of the forks I use a vernier caliper & pry up on the fork’s dust seal & pull it up the fork slider a few inches. It is much easier for me to measure between two metal objects on that fork leg than using the fork tube as one end & a bendable piece of rubber on the other. Measure the distance from the fork tube to where the fork slider attaches to the fork bottom. That is your front suspension’s total travel.

Out back I support the bike on a rear stand & I find a steel rod that is just a little smaller than the hole in the swingarm pivot is. You want a rod that is long enough so it sticks out about one foot one each side of the bike when it is shoved into the swingarm pivot hole. Once the rod is in place put the bike on a rear stand, position jack stands on either side of the bike so they sit pretty close to the bike. You want the jack stands to be set at a height that is just a little below where the rod is sticking out with the bike on it’s rear stand. Now slowly take the bike off the rear stand & the rod in the swingarm pivot hole will support the bike in a way that allows that swingarm to drop down as far as it will go. Now I take a piece of string & tie a small washer to it. Holding the string & letting the washer dangle I move that loose end of string around the rear subframe of the bike so the washer lands just just above the rear axle on the rear swingarm. I usually drag the thread over until the washer is sitting directly in the middle of the rear axle & then I slide the string forward just a few millimeters. I do this because when you sit on the bike the suspension collapses & the “loaded” suspension position will have the axle move forward slightly relative to the spot you just found. Go ahead & mark that spot on the rear subframe & where the washer came to a rest on the top of the swingarm with a sharpie. Often times I will grind a little notch there in place of those marks. You can now make a measurement of this distance so you get an idea of how far apart these two spots are when the suspension is unloaded.

While sitting on the bike parked close to a work bench or a wall you can balance your weight while you have both feet on the foot pegs & balance yourself using your left arm to hold on to that "fixed" object. While you grab the front brakes your buddy will lean over the other side of the bike & push down firmly on the upper triple clamp assembly & then let it rise up slowly (without bouncing). Your buddy then measures the front suspension travel left. Do this 3 or 4 times & have him record his measurements of the "push down sag." Then have your buddy lean over the front & side of the bike (while you still have both feet on the footpegs & are somewhat leaning toward the wall or workbench) & have him lift up on the triple clamp or clip ons with both hands & then slowly drop the front end down without bouncing. Then get him to measure the suspension travel left. Do this 3 or 4 times just like before & record the measurements. Label these as "lift up sag" measurements. Keep in mind when you are lifting up & dropping or pushing down & letting the front end pop back up there is a bit of human interplay going on here. No matter how hard you try you will always interfere with the suspension moving back into place. Try not to interfere too much but do not try to let it bounce it either. If you use a consistant technique you will find the measurements you make will all be very close to each other. I find when I get tired I change the amount of pressure I exert in either direction & then I get numbers that don’t make lots of sense. So I either toss out the reading I just got & average the others or I just redo that one trial one more time. After using this technique on several bikes I think you will be able to predict if the number you get on one particular trial will be off due to your technique changing unexpectedly. Be consistant.

Get an average of all the push down measurements & then get an average of all the lift up measurements. If any of the measurements is way off the mark as you start to add them together to find an average just throw out that measurement. Then you are left with 2 average numbers, a lift up number (averaged) & a push down number. Add these two numbers together & divide by two to get the "true" sag number. The difference between the two sets of numbers you got in your measurements is how much stiction you have in your particular forks. I have seen up to 11mm difference in these two set's average number & less than 2mm in others. When you set your front rider’s sag adjust the spring preload adjusters to get very close to 34mm rider’s sag in the front & 30mm of rider’s sag in the rear. Do yourself a favor & record how many lines or millimeters of that preload adjuster is showing/left over when you make changes & take measurements. Once you make a change often times you will have to keep cranking down or back off the adjuster beyond that initial change. Knowing how much you backed it off & how much the rider’s sag number changed as a result will help you figure out how much more or less preload you should adjust for to get that rider’s sag number set properly.

Last edited by Mr. DOBALINA; 08-31-2007 at 03:02 AM.
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Old 08-31-2007, 03:01 AM   #8
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PART TWO - EVALUATING & SETTING COMP & REBOUND DAMPING


Regarding evaluating your own bike's suspension potential there is no other "true" way to do it then taking notes on where your suspension settings are at to start with & then do a bouncing evaluation. What you are trying to do with this evaluation test is to change settings & then bounce the bike around to get a feel for what damping occurs as the bike's suspension is compressing (comp damping) & when it bounces back up (rebound damping). Dialing out comp damping several more turns or about a dozen clicks out from maximum (counter clockwise) will give you a setting that offers no comp damping from that damping circuit. The same holds true for the rebound damping circuit. The spring itself will offer some though & getting a feel for what that feels like on your particular bike is important. Then you want to see how much of a change there is between that/those settings & 1 click or 1/2 turn out from maximum.

Basically you want to be able to see/feel big differences in feel when changing settings when you are bouncing up & down on a bike's suspension while it is at rest. If not, then we know your suspension is already compromised which means it may be a combination of things at play that are making your bike handle badly. Once you determine that things internally are working at least at a decent level then you can get into how a bike should feel when you bounce it at rest. Unless you explore how it feels with no damping & with "supposedly" tons of damping dialed in at rest you will get into problems when you try figuring out what it’s doing on a road. You cloud up the analysis with lots of other physics issues that can make things complex to separate if you have more than one suspension issue going on. Having worked around suspension tuners that do this stuff on race bikes I have learned this is the way they help people out. Otherwise you are just guessing using those tried & true suspension issues lists you see floating around. Those that say when your bike pushes wide at the exit of a turn your compression damping is set too high, etc. Those lists are great, unless you have more than one issue going on & most of the time most street bikes have 2 or 3, sometimes more issues happening. If your rider’s sag is not set, and your bike has old worn fork slider bushings combined with old fork oil those lists will be pretty much useless because what is making you drift wide is not the comp damping although it can play a role. Best to set things to a good baseline first & then use lists like that to help you fine tune your settings.

If you do the bouncing test & can feel quite a bit of difference between no damping dialed in & lots dialed in you have a baseline to work with. If you have your rider's sag set you can figure out how much comp damping is happening up front. From your "zero" comp damping setting go ahead & dial in (clockwise) either a few clicks or turns of comp damping & bounce up & down on the bike. Is there any added resistance to your bouncing? To double check dial out the same amount of damping you just added in & then bounce it again. If you felt nothing extra resisting then go ahead & try adding one more turn or 2 clicks from that point & try bouncing it again. Take notes on where your "zero" point was, that is how many clicks or turns it was out from maximum damping. If you found new resistance from that point back the adjuster back out 1/2 turn or one click to see if you "overshot" the point where resistance was kicking in. Going back to your zero point is a good way to do it as well as you are double checking your work. Go back & forth until you find that point where comp damping is finally kicking in. Why do this? Because as your fork oil gets old & when the internal slider bushings wear this point will move, in some cases radically. Find that point & document how many clicks or turns it is out from maximum. From that point you want to use 2 clicks or so closer to maximum as a good street baseline for comp damping. I use "or so" as some suspensions will just start kicking in a little comp damping at 1 or 2 clicks out from maximum! Yup, I've seen it from a few bikes. In that case if you need to ride the bike without changing the fork oil set comp damping at 1 click or 1/2 turn from maximum & realize your suspension pretty much sucks as a baseline & don't expect too much.

For rebound damping (once again set rider's sag first) do the same analysis you did with comp damping but try it with the rebound adjuster at least one click out from maximum or 1/2 turn out from maximum. If you set rebound to maximum & leave it there the bike will not handle right even if it is set at a desired popping back rate. Finding out where the rebound starts to kick in will help you gauge how old the fluid is & what state of decay things are at. Record that reading & keep it & the comp notes handy for when you do this stuff again. I think a good setting for a "smooth" track is when the bike's suspension rises up slowly after being compressed. That is a little less than a second for the front end to come all the way up after you push it down. That setting will not work on a bumpy track or on your typical streets that aren't that manicured. For street use I dial the adjuster 2 clicks further out (from maximum) or 1/2 turn & then use that as a baseline. Ride the bike again over some bumpy roads & if the bike still reacts harshly over a set of bumps keep backing out that rebound adjuster in small increments until the ride over surfaces like that is bareable. If you never ride over very bumpy road surfaces & like to go faster over smooth road surfaces keep that rebound adjuster cranked up.

Now do all that you just did up front to the rear of the bike. When you are done park your bike next to a wall & stand up a little on the footpegs & while balancing the bike bounce the bike's suspension up & down. It helps if a friend watches this. You want the bike's front suspension to bounce down & come up at the same rate & in unison with the rear. Dial in more compression damping to the side that is bouncing down faster than the other & the same with rebound damping. Ask your friend for input as I have found this is helpful. Then take the bike for a ride down a street with little traffic that you know has some bigger bumps/dips in it. Ride over these bumps & pay attention to what the front & rear suspension are doing. You want them to be in sync so that if you are riding hard over a series of bumps the front & rear will go up & down together & setting the suspension up that way will keep the bike under control. Also bouncing up & down on the pegs as you ride down a quiet street with a smooth surface to double check your work is a good idea.

Checking & setting rider's sag will take you about an hour and a half, doing the comp & rebound stuff about the same or possibly a little longer. I have ridden a poorly set-up TLS on a race track several times before I started learning these things rather slowly. The difference between a nicely set up bike & one that is just the way it was sold stock several years after it was released is truly amazing. It’s like they are 2 different bikes. I have ridden a few friends/members bike's at street speeds that scared me. I cannot imagine what it would be like trying to ride them fast & around corners at speeds way slower than that found on most tracks. Makes you wonder?
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Old 08-31-2007, 08:20 AM   #9
convict231688
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i appreciate it. thats is the answer i needed thanks
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Old 08-31-2007, 08:36 AM   #10
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Quote:
Originally Posted by Mr. DOBALINA View Post
You need to set up your bike's suspension & the spring preload aspect of this depends on your weight. I did a write up on this for another website & here is a copy & paste of that piece:
dob, great info, thanks gonna spend this holiday weekend dialing in a few things on my bike and this will be a big help.
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