Rear Suspension Pre-Load

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Some great information here, but can we talk about how many "clicks" on the OEM shock?

The owners manual states that the standard setting is 7 clicks. Being heavier than average, I dialed it to double that. I didn't dial in any more pre-load and went out for a ride with a passenger. My best guess for her weight (I won't ask) is about 150#. The bike felt pretty good, but I did bottom out on a dip that I didn't think I would.

Next ride with passenger, I'm going to add another 7 clicks, but it would be nice if there were some guidelines for how many clicks for how many pounds.
 
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I would crank it as high as it will go, if it still bottoms out in the same conditions (passenger and same bump, same speed, etc) then you'll need to get a heavier spring....good luck.....ff
 

MajorTom

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This is all presuming the preload system is fully charged with hydraulic oil of course. Otherwise the clicks only indicate the preload adjuster knob is turning.
 
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I would also state that increased ride height {back only} results in a steeper steering geometry that will {possibly} contribute to the dreaded "wobble"? ....anyone experiment with this?
 
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My theory is that if you stiffen up the rear end with preload it would be less prone to weave. I also think weave is more to do with aerodynamics of the fairings, saddlebags and if you have a top box.
 

dduelin

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Snipped...........Adding more pre-load simply increases the height of the rear end of the bike - it doesn't make the suspension stiffer, or compress the spring further.
Adding preload does compress the spring further. That is how it raises the ride height.

Just look at the top of the shock when you wind in preload. If the mechanism works properly the top spring seat moves downward as preload is wound in. (about 10 mm of travel if oil is full and all 36 clicks 18 full turns is used). Imagine for illustration it takes 100 lbs to compress the spring 10 mm. That would be a 10 lb/1mm spring rate. A free spring of this rate held vertically will compress 10 mm when a 100 lb weight is set on top of it. The spring is held between two seats on the shock which get closer together as weight (force) is added.

Move the preloader down 10 mm adding 100 lbs "pre" - "load". The extra 10 mm of compression on the spring means it takes more force (100 lbs more to overcome the extra 10 mm added "pre to "load"ing it with rider) to initially compress the shock. Once the shock starts compressing it does not take any more force than before to compress it - 210 lbs of force compresses it 11 mm, 310 lbs of force compresses it 21 mm. Since the bike did not physically get any lighter then same weight of bike compressed the shock 10 mm less and the ride is higher by 10 mm.
 

dduelin

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However we choose to understand or describe it the result is the same. Adding more preload compresses the spring. Because the spring is free to pass the additional force thru the swingarm to the tire to the ground the rear of the bike rises and the spring in this case measures the same length before and after but that does not always hold true with all shocks on all bikes.. If the spring rate of the shock is too soft the additional preload required to get rider sag correct tops out the shock before it fully extends when weight of rider(s) is removed - there will be no free sag. The distance between spring seats will be less than before additional preload. If this happens too much preload was required to get rider sag correct. This illustrates how the relationship of free sag to rider sag indicates if spring rate is in the ball park for individual riders.
 

CYYJ

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For us over 250, 275 and even 300 lbs guys, usually with large women passenger's, any settings suggestions?
(a very late response to the question)

Dave:

The owner's manual states that the maximum weight capacity of the ST 1300 motorcycle (this means rider, passenger, all cargo, and all aftermarket accessories) is 432 lbs (196 kg).

I might be more cautious than most when it comes to weight limits - this a result of my background as an aircraft pilot, where mass & balance limitations are taken very seriously and overloading, even by a wee bit, is a criminal offense - but still, I think it would be unwise to exceed the maximum load limitation published by Honda if for no reason other than that we don't know what engineering limitation caused Honda to set the maximum load limit where they did.

For example, I doubt very much if frame strength is the reason for the limit, but I think that the weight-bearing capacity of the front tire, when brakes are fully applied in a panic stop and up to 2.5 or 3 times the total static weight of the fully-laden moto is applied to the front tire, might be the limiting factor. If that is the case, a hard stop when overloaded might result in a blowout of the front tire at the worst possible time.

Michael
 

Dave.David

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(a very late response to the question)

Dave:

The owner's manual states that the maximum weight capacity of the ST 1300 motorcycle (this means rider, passenger, all cargo, and all aftermarket accessories) is 432 lbs (196 kg).

I might be more cautious than most when it comes to weight limits - this a result of my background as an aircraft pilot, where mass & balance limitations are taken very seriously and overloading, even by a wee bit, is a criminal offense - but still, I think it would be unwise to exceed the maximum load limitation published by Honda if for no reason other than that we don't know what engineering limitation caused Honda to set the maximum load limit where they did.

For example, I doubt very much if frame strength is the reason for the limit, but I think that the weight-bearing capacity of the front tire, when brakes are fully applied in a panic stop and up to 2.5 or 3 times the total static weight of the fully-laden moto is applied to the front tire, might be the limiting factor. If that is the case, a hard stop when overloaded might result in a blowout of the front tire at the worst possible time.

Michael
I completely agree with what you wrote. And I already knew about the 400 pound limit, that's why I was asking. On my VTX 1800 I went to a car back tire when I noticed I wasn't getting the mileage I should and a shockmount was bent. After replacing all the bearings in the rear hub, the car tire being able to handle so much more weight, replacing the shock mounts, and new Progressive heavy shocks, I feel much more comfortable about having a lot of weight on the back of that bike.
What about the ST 1300? I'd rather not go dark side but at least putting a heavier spring in the back suspension seems like a good idea to me.

Sent from my SAMSUNG-SM-G935A using Tapatalk
 

mlheck

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The ST is sprung for a 170lb rider. Anything heavier and you better start upgrading the suspension. Ractech suspension has a spring chart that will show you what is stock on this bike, and what you need for your weight.

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T_C

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Even at a combined weight of 350, (passenger and rider) I was feeling the rear tire max its suspension limit.
 
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For a good, generic primer on setting up a bike's suspension, Dave Moss is very good. He has a bunch of vids on Youtube, very clear, easy to understand, simple. Made a lot of sense to me. I was one to just get on and ride, always considered "shocks" and "suspension" way over my head until I had several conversations with Ted Porter who recommended these vids. It's really very simple to check the basics. All you need is a tape measure and note pad, one eye, and half-sense.
Dave Moss Tuning, Youtube vid
 
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I'm definitely on the side that says the spring adjustment affects ride height. How can a given weight not compress a given spring a given amount, regardless of starting and ending height? As long as the shock is not hitting either travel limit, a given spring will change riding height for a given load. When you move one end of a spring, the other end will move the same amount under a given load; how can it not? The adjustment is for keeping the suspension in the "sweet" portion of travel when supporting a given load.

I adjusted the rear suspension about 1/2" at the shock because I weigh more than the previous owner, and the improvement in handling vastly improved due to the change in steering geometry. Raising the rear made the forks more vertical, quickening the steering and requiring much less steering effort, which made the bike more responsive and requiring less steering effort to get it to lean, which in turn improved riding confidence. It's easier to impart small steering efforts when not having to "modulate" a great effort.
 
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What a fun discussion! I love suspension as a topic.

My take is that the spring will compress to a point where the resistance to further compression balances the force being applied, so it compresses no further unless more force is added. That balance point can be shifted by adding or removing preload, which in effect makes the bike sit higher or lower in the suspension stroke (or more or less sag to put that another way). What can be perceived as "stiffer" is the behaviour of the bike on a negative object e.g. when the wheel hits a dip in the road. If there is insufficient sag (and the guidance above to have about 1/3 of the total travel is spot-on) then the shock will top out easily and the wheel can lose traction as it is unable to extend far enough to keep the tyre in contact with the road, which can be perceived as harshness. Excessive rebound damping can present in the same way.
 
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My take is that the spring will compress to a point where the resistance to further compression balances the force being applied, so it compresses no further unless more force is added. That balance point can be shifted by adding or removing preload, which in effect makes the bike sit higher or lower in the suspension stroke (or more or less sag to put that another way).
Yes, but the crux of the whole debate is that, for a given weight, the compressed spring will be the same length. Adjusting the spring only adjusts where along the shock's travel that length will reside. It has no effect on the static length of the spring.
 
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What can be perceived as "stiffer" is the behaviour of the bike on a negative object e.g. when the wheel hits a dip in the road. If there is insufficient sag (and the guidance above to have about 1/3 of the total travel is spot-on) then the shock will top out easily and the wheel can lose traction as it is unable to extend far enough to keep the tyre in contact with the road, which can be perceived as harshness. Excessive rebound damping can present in the same way.
Agree 100% that excessive rebound dampening produces a similar "harshness/stiffness" to using too much preload. I demonstrated this on a sport bike I had with fully adjustable forks. I could dial the harshness in/out using just the rebound dampening adjustment screw and nothing else. I'm a bit skeptical that it was because the forks were actually topping out, I would think that would create a perceptible "clunk" when it hit the mechanical stop, and I never felt that. But I'm convinced that whatever happens when you crank up the preload too high on regular forks, it creates the same effect of having too much rebound dampening, which produces a stiffer/harsher feeling ride.
 
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Agree 100% that excessive rebound dampening produces a similar "harshness/stiffness" to using too much preload. I demonstrated this on a sport bike I had with fully adjustable forks. I could dial the harshness in/out using just the rebound dampening adjustment screw and nothing else. I'm a bit skeptical that it was because the forks were actually topping out, I would think that would create a perceptible "clunk" when it hit the mechanical stop, and I never felt that. But I'm convinced that whatever happens when you crank up the preload too high on regular forks, it creates the same effect of having too much rebound dampening, which produces a stiffer/harsher feeling ride.
You also don't feel any sort of a clunk when you (inadvertently) pull a wheelie; the forks are definitely fully extended at that point! There is a top-out spring in the forks on the outside of the damper tube (or inside on the ST1100 damper) that catches the end of the fork leg and stops it from coming to a sudden stop. I don't recall anything similar inside a shock but it maybe a hydraulic stop.
 
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Yes, but the crux of the whole debate is that, for a given weight, the compressed spring will be the same length. Adjusting the spring only adjusts where along the shock's travel that length will reside. It has no effect on the static length of the spring.
Yes that is quite correct.
 
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You also don't feel any sort of a clunk when you (inadvertently) pull a wheelie; the forks are definitely fully extended at that point! There is a top-out spring in the forks on the outside of the damper tube (or inside on the ST1100 damper) that catches the end of the fork leg and stops it from coming to a sudden stop. I don't recall anything similar inside a shock but it maybe a hydraulic stop.
When I was able to increase the perceived harshness by increasing the rebound dampening only, the extension distance needed to "top out" the forks was the same as when I adjusted in less rebound dampening and the harshness went away. The ride height/sag/preload was identical in both cases because nothing changed in the spring preload setting. Intuitively, I would think that if anything, more rebound dampening would slow the rate at which the forks extended, meaning they would be less likely to "top out" compared to the less rebound dampening case. That seems to be contradictory to your claim, can you explain that?
 
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