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Huzo's OP and #12 are correct. Some of the other are correct, others are not.Preload affects ride height, steering geometry and handling.Too little preload can result in the suspension bottoming.Too much preload and the suspension might top out during the rebound from a bump, causing the wheel to leave the ground (and traction).Ride height examples - if you have a spring with a rate of 100 lbs per inch, and the shock is vertical (usually the shock is at an angle but that require trig - so we won't go there_.With no preload, if you put a load of 150 lbs on the bike, directly above the shock, the shock will compress/shorten 1.5".If you put a preload of 50 lbs on the shock by moving the adjuster 1/2 inch, when you put the 150 lb load on, the shock will shorten 1".If you put a preload of 100 lbs on the shock by moving the adjuster an additional 1/2 inch, when you put the 150 lb load on, the shock will shorten 1/2 inch.
Ncdan,The normal layout of those type of shocks will have the stepped ring and a "pin" that fit s the step.That's the preload - you'll have three to five steps at different heights and adjust it by rotating the ringwith a "C" spanner. I'd start by setting it to the middle as a base point and go from there. The adjustment at the top is most likely for Rebound Damping - too much will slow the suspensions return to it's original position too much resulting in the suspension packing down over say a series of bumps.Too little rebound damping can create wallowing as the spring overcomes the damping and pushes the suspension back after a bump past it's original starting point.Think of the spring on it's own with no damping - you hit a bump, the wheel bounces up with the impact and will bounce higher than the actual bump and then return and also push past the starting point and then cycle back and forthuntil it settles back at the starting point, like early Cars with no Shocks. The Compression Damping controls the springs action so it doesn't just bounce up wildly and follows the bumps contour more closely. The Rebound Damping controls the springs action as the suspensioncomes back to it's starting point so it doesn't overextend.Maurie.Thanks Maurie, that explanation makes things clearer for me. I weigh in at 165 so I probably need to have my spring a little longer from half way wouldn't you think?
Sorry, if this is off topic, but how can we assure that pre-load on both shocks is set identically (assuming we have two)? So one is not carrying more that the other? Is that as simple as counting threads?
Nothing's ever off topic Waxi, take it anywhere you like. Fair question too BTW.
Just want to be nice. I am afraid of Pete, haha :)
Sorry mate, Pete who ?
Take the two rear shocks off, hang your bike from the two top shock mounts to a scale. Climb on the suspended bike and read the scale. Divide that number by 2. That will give you the maximum spring rate to support the bike with no preload. If you want 1 inch of preload, reduce the spring rate by the amount required to compress the spring 1 inch. Sounds easy. Anything less than an actual weighing of bike and rider is all guess work. Adding a passenger and gear will require additional preload. Progressive springs are useless because you have to adjust the lighter rate out to get the ride height. Same with the front. Suspend the bike from the handle bars while sitting on it. Take a weight reading.
Roper. He is very active here on WG.
Are there another recommended books that explain things simplistically ie "if it does this do that"
Nah, he's a shrinking violet. Scared of his own shadow...!
How do you get around the fact that when you hang your bike, the weight vector is vertical, but on the bike the shocks are angled forward, so the load on the shocks is more than the actual mass they're supporting, sounds like a bit of buggerising around.
There are some spring rate calculators that will give you the compensation factors based on the angle of the shock. But a good starting point is needed to use the calculators formulas. I found one that was used for front auto suspension set up. You could put in several variables and it would give you the spring rate. One variable is the top spring mount load.
Oh righto.
Ncdan,Except that you went from one extreme to the other, that isThe recommended method. It's best to only change one thing at a time though so you don't get confused as to what caused what. Also not all shocks are made equal - the quality of the damping and the effectiveness of adjustments is whatYour paying big bucks for with the top notch stuff. Horses for courses - if your not an aggressive rider you won't needOhlins just good quality shocks with effective adjustments.Waxi,Might be overthinking it a bit - while Spring rates ona pair ofShocks might not be exactly matched they'll be close and witha twin shock bike the pre load is a stepped adjustment - put each On the same step and your Golden. Screw thread Pre-load is More the norm on Monoshock bikes.Maurie.
Ncdan,With you and whatever you are carrying on the bike, it should be about 1-1 1/2 inches compressed from the fully extended position of the shocks. About 1/3 of the travel of the suspension is a good ball park place to be.
After reading the explanations from you guys, which were very accurate and complete and doing a little further research from other sources, I have a conclusion on my own. As I am fairly new to the guzzi world with my calvin, I am a old salt in the ridding world. I have ridden 50 years now and owned dozens of different makes, sizes and styles of bikes. I have experienced old technicality up to the most recent, from basic suspension to air to this Calvin with the dampening and rebound settings. I humbly offered this info to only put a little weight to my findings. I just returned from conducting an experiment with my calvin just to satisfy my own curiosity as to the effects of the adjustments on the suspension the calvin offers. On the front forks I set the dials on both compression and rebound, all the way to the - negative setting. I proceeded to a rough curvey road about two miles long. I road the road mildly aggressively. I then set the settings all the way to the + setting and road the road the same way. My results are this. If I had had someone to set the settings without me knowing which one, both of full + them full - in all honesty I would not have been able to say which was which. There were no noticeable difference for me. I did not ride aggressively to an extreme but didn't mosey on either.On the rear with the setting cranked all the way up or shorting the spring, it's a little harsher on the bumps than with the setting all the way lengthening the shock spring.so I decided to simply make the adjustments half way on both ends and leave it to the heck alone. I will say I'm of the opinion that if one wants a drastic change in a bike like mine they might as well figure on spending big bucks and replacing the stock ones with aftermarket high Preformance type suspension.Thanks for reading and responses are welcome just keep in mind my findings are just an opinion on my calvin and no one else's situation or bike.
Jeez mate you don't have to offer anything humbly. We're (almost) all amateurs here. I've never buggerised around with my Norge fork settings, just like they were from the factory and I've owned it 8 years and 110,000 k , I reckon just leave well alone. They soak up bumps beautifully and the bike does not wallow or weave at all so what else do you need ?
Thanks for the words of encouragement "mate";) I just figured those settings were there for the ridder to fiddle with so my curiosity got the best of me. I'm beginning to reason that unless you are ridding the pure hell out of one of these bikes and pushing them to the brink of maximum Preformance, these settings don't count for much. In all honesty I wish mine didn't even have them so I wouldn't have to think or worry about having it perfect as I am a perfectionist. Which is a curse:(
I think most people set their bike up to a good "median" and then ride around conditions, you don't see many people stoppedby the side of the road adjusting their susp. because a set of goodcorners is coming up!Pre load and Rebound become more important when your Dinkingor carrying a load, I have three settings which cover my differentneeds and can change them in a couple of minutes and it's veryworth it.Cheers Maurie.Sounds reasonable Rand. I'm going to set everything toward the middle of the road and make changes as I am sure the bike is weak in one situation or the other. Sooner or later I'll be satisfied with what she does in any situation. I think the key is that you know how your bike will react in any given environment or situation.