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Here is a complete course of suspension tuning, front and rear

Started by yoshimura, November 22, 2015, 10:02:59 AM

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yoshimura

Here is a complete course of suspension tuning, front and rear

On a shock, you have three settings: preload, rebound and compression.
If there is only one, it is the preload, if there are only two, it is preload and relaxation. We can then go further, but by changing parts (valves or spring) or oil. But in general, there is no need to buy new parts to find the right setting (except when using non-standard, or competing for a raid with 3 tons of luggage, for example).

Prestressing is the basic compression spring when it is at rest. It does not make it harder spring itself (for this, the only solution is change), but to some extent, it gives the impression. Preload is adjusted depending on the weight onboard (only rider with passenger, with luggage) so that the height of the motorcycle once charged is correct. If you have too much preload, the bike does not fit enough, and when you walk into a hole, the wheel can not come down enough to absorb it.
If there is not enough preload on the contrary, the bike is too low, and the first coming bump, the shock will come to a stop and then hang. Very backlash in perspective. It is said in this case, the suspension heels. The idea is to find a just preload not hound or below (a bump) or up (in a hole). On a road bike or road typed comfortable preload is adjusted so that the bike sinks a third of travel when you go up top (where appropriate with the passenger and luggage).
For this, we measure the pitch relaxed damper (optionally drawing the motorcycle slightly upward) and then rising above. The difference in height must correspond to a third of the travel of the damper. It's been about 4 centimeter driving on a road, not 6 or 7 centimeters on a trail. For sports in "circuit" settings, use a smaller sinking value of 2 centimeters. Indeed, there are very few holes on a circuit, then there is very little need that the suspension can relax. By cons, in order to take the corner without (too) rub, it is necessary that the motorcycle is quite high, hence the minimum value of 2 centimeters. For the fork, it is similar. One third of used 'normal' race, and only 1.5 centimeters for use circuit. I have much detail here because it is the most important setting, and yet one for which we can provide figures. Preload adjustment should be granted, that is to say that the bike must keep are plate. If the bike is leaning forward or backward than the manufacturer anticipated, its handling and its reactions will change (not necessarily degraded, it may be desired). A bike leaning on the front (much preload at the rear) will be more manageable and will spend more power out of corners (better traction). A bike leaning on the back will be more stable in a straight line and can brake harder. But you can not have your cake and eat it too, if it promotes a behavior will be lost on other tables. On the road, it is best to maintain the standard ride height to get the best compromise "all purpose" defined by the manufacturer. Edit the plate too can degenerate into problems or louvoiements speed wobble. Now hydraulics. This is to adjust the diameter of the oil passage holes. Over the hole is, the more oil is hard to pass, so the more the movement is braked. We talk about "close" to further hydraulic brake the movement (by tightening the adjusting screw), and "open" to make it free (by loosening the adjusting screw).
If you do not know where the adjusting screw, is simple:
To a rear cushion, the compression adjustment is at the top of the shock absorber, the adjustment trigger is down.
For a fork, it is exactly the opposite. Relaxation is top, bottom and compression.
Hydraulics, we can do many things, there is no ideal value that fits all cases.
However, it must follow some basic rules, which are:

- Compression must be less constrained than relaxation.
When in doubt, it is better to work on relaxing on the compression, the effects of which are very sensitive and can be dangerous if you go tickle the extreme. So easy on the closure of compression screw relative to the original setting.
Beware also, the progressive adjustment varies from one screw to the other. Do not say that since it took 5 clicks in the back, it will take much in front, it may have nothing to do in the effects.

- On bad roads, open water should be preferred so that the wheels follow the uneven ground without the bike becomes jerky. On billiards, to roll very fast, should be preferred hydraulic very closed to avoid pumping suspension that generate more or less troublesome behavior inaccuracy (too open water can easily give problems to sway due to pumping). The two are incompatible, we must find a compromise.

- The front-rear hydraulic adjustments must be granted. A very restrained with a fork damper very free, it will not at all. The reverse is also true. The Triumph of the original problem is that they have too soft a fork and rear shock too hard, and despite the possible settings, you still have to do with more or less. There will therefore be a bike that pump forward at high speed, despite a front reassuring at low speed, but the back will still be uncomfortable and somewhat hopping on bad road. To check the agreement, it's simple. When stopped, jumping on the saddle, you should feel the bike and push back horizontally.
The fork and the damper must react together at the same time and over the same distance. If this is not the case, one adjusts compression and / or expansion in the front or rear. In any case, the motorcycle must be able to penetrate more easily it goes back (but not too much difference anyway, otherwise it may cause other problems, I will return).

Then it is the road test, to see that all is well. It made its tests on a very bad road. The retarder and rumble strips are also very good indicators respectively for the front and rear.
On a retarder, anyway, the bike must first go up, then back down. If it rises too sharply at the beginning of the rise is that the compression is too closed to allow the damper to absorb the bump. If it absorbs bump, but tends to take off once reached the top (rebound) is that the compression and expansion are too low, the suspension sinks too at first, but then nothing prevents the spring to relax too soon.
The idea is that compression must be low enough to absorb the bump, and closed relaxing enough to prevent the motorcycle is projected upward when the spring relaxes. By cons, do not compensate for too little compression too much relaxation, otherwise the descent retarder does not go well. Indeed, if the expansion is too closed, the wheel will not come down fast enough to stay glued to the road. Easily felt through the retarder accelerating: if the rear wheel slips on the descent retarder is that relaxation is too closed. By cons, if the motorcycle continues to pump after the passage of the retarder is that relaxation is too open to be able to brake the spring rebounds. The retarder serves primarily to adjust the rear shock. On a retarder, as it is tested whether the bike will not close behind. It feels great when a fork or a damper abuts, very brutal. If it heels or we add preload, a little compression is closed (but do not abuse it by closing the compression, we must prefer the preload setting). Place retarder without feeling anything or lose any traction is impossible in the current state of technology. And promote this or that is not good for others. We must find a compromise.

The hole is also a good test, we pass over speeding to see if the rear wheel slips. If this is the case, either the trigger is too closed (as the retarder, but normally it has already been verified), or there is too much preload the spring, so too little backlash so that the wheel can go in the hole before coming to a stop (the good test hole should be in the 3-5 cm deep, a bitumen end missing is perfect for this). This test should confirm the preload adjusting actually static and the relaxing setting found on the retarder.

For the fork, a strong brake on rumble strips is a very good indicator. The fork should not hound when moving on rough strips, otherwise you have to add preload. The compression must be open enough not to generate small blocks ahead on the rumble strips. But if the fork heels, anyway we will blocking primers. If despite the preload adjuster, fork continues to hound is that the spring is too soft. The correct solution is to change it, but to some extent can be compensated by closing the compression. We must seek the best setting for not hound nor too slow fork, which would prevent him to follow the road profile. The trigger must be curbed as compression, it is above it which will avoid high speed pumping, but not too much, otherwise once the front wheel can no longer follow the road profile. When a fork is set, it must allow you to slow down relatively hard on the angle strips on rough or bumpy road without being afraid. If it moves scarily, it is clear, the fork is set incorrectly. To "scientific", we put a collar on Serflex tubes to measure how far the fork downwards during heavy braking on a slightly uneven asphalt. It must be almost completely sinks but not hound (we try to keep one centimeter margin). The idea is to try to use almost the entire race possible, without going to stop, neither up nor down. If you feel the fork type top and bottom despite the settings is that the spring is too soft. If instead we only use a small part of the race is that it is too hard. One can partly compensate for a too soft spring by closing the hydraulics, but the real solution is to change spring. In all cases, static, it must feel that the settings of the hydraulic fork to be freer than the rear shock absorber, since the weight to be braked is less important.

To check all, a good fuck on a bad road will be the justice of the peace. One can for example be seen from the rear of calibrations over a series of large undulations or bumps, while the test for the retarder is good. One can also experience poor motor skills (skating back) acceleration on bumps. These two phenomena are a sign of too closed rear trigger. Poor traction is due to the fact that the rear wheel does not descend to the bottom of the holes, because it is too constrained rebound, so she "flies" the field. Tailgating may be due to a very low compression and a very strong relaxation. In this case, the shock absorber has no time to relax between two bumps, and sinks more and more until it abuts on a series of bumps (which is rare on a road or sports , rather it happens with cross Machinery enduro). If we see the guidonnages by re-accelerating out of corners, it's either a problem of too much on the back plate (not enough preload on the rear) or excessive preload on the front makes the fork remains in top stop, making the front wheel bounce slightly bump bump (but for this simple little rough bitumen sufficient to trigger a speed wobble). If one is afraid of braking, it's either the fork heels (lack of pretension) or the hydraulic (especially compression) is too closed.

Finally, the test of the great curve at high speed motorway will allow to see if the test result of the bad road, we did not open the hydraulic excessively. Indeed, for good stability at high speed, requires a closed hydraulic (compression and rebound), in order to avoid pumping that cause louvoiements.

After a few passages retarder braking on rough strips, poor road and highway, each with a static verification of the suspension agreement, we finally find the right compromise in terms of the use made of motorcycle. But it takes quite some time, and you can slightly change his mind from one day to another. When making adjustments, it is always best to play on a parameter at a time, in a light way, and give it a try to see clearly the effect of this parameter, even readjust according to another later. That request is experience, or a lot of patience when we did not used. After, his machine is chosen to type more or less flexible depending on the use made of it (still rides on country roads or Arsouilles donf on the highway).

Georges, Jungle Biker the author of this course.

BOBR6 84


h106frp

"To check all, a good fuck on a bad road will be the justice of the peace."  - quote of the day  ;D


BOBR6 84


yoshimura


Boerenlater

I stopped gaming (and GP-Bikes)

HornetMaX

Quote from: h106frp on November 22, 2015, 10:14:18 AM
"To check all, a good fuck on a bad road will be the justice of the peace."  - quote of the day  ;D
This could make it straight to engrish.com :)

CapeDoctor

i found this little  suspension setup guide to be really useful for myself: http://www.sportrider.com/suspension-tuning-guide-handling?image=0
i much prefer this sort of problem = solution guide, much easier for me to get my head around than the more technical stuff, lol

8)

HornetMaX

Quote from: CapeDoctor on December 05, 2015, 06:46:21 AM
i found this little  suspension setup guide to be really useful for myself: http://www.sportrider.com/suspension-tuning-guide-handling?image=0
Properly tuning a bike is not easy. Just check the explanation for "Terry". Basically it goes: "Try this and that. Or maybe the opposite of this and that. Whatever works better." :)