wildman said:
NKW570, dont be afraid to put the stacks apart & find out what's in there. Heaps of info in the doc. Just be well prepared with heaps of clean benchspace & a pen/paper. It'll give you a benchmark to work from when you make changes. I've had the forks on my '08 FS650 at least 8 times now screwing around with the shim stacks. I can have them out & a shimstack change made in 1 hr now ( almost with my eyes closed :lol: ). At least you'll get a better understanding of what does what & above all else, quality shed time.LOL
Thanks Wildman, but me and a set of shimstacks would not be quality shed time, trust me on this. If your shed was closer, my forks would be there along with a few beers. I'd prefer you to keep both eyes open when doing mine though :lol:
Going back to the handling and suspension on the frontend, i am now a happy bunny having raced at the weekend. But no thanks to the tuner, the revalve was fine, the oil level was not. I had to take 60ml out of each fork to get themk to work and the difference is night and day.
My current settings for the 09 fe570, woods enduros, 190lbs without gear are:
REAR: 80/250, 7mm preload, sags 38/110-115, wheel set back, comp 14, rebound 22, HS comp 2 turns out.
FRONT: 4.6s , 5mm showing above clamps, 0 turns of preload, 22 comp, 22 rebound.
All equates to a very nice ride.
The other issue that remains is the 22mm offset which more and more riders are saying gives a better feel to the front, even on the 09s, which dont have the same setup/geometry as the 010s. As i cant afford an 010, i may have a go with the E-axle later on.
I found this well worded piece of script on offset and trail which explains it really well, without having to go to physics class.
Cheers,
Nick
Increasing offset actually reduces rake, if no other adjustments are made. As the offset increases, there is a vertical component as well as a horizontal one, that actually drops the steering head a little.
Look, there seems to be a lot of confusion about stability, response, and rider comfort. I even read some of the stuff on Emigs's site, and it was gibberish from a physics standpoint (but is probably based on very valid real world experience, and more about that later). So I guess owning a CNC machine does not mean that all the laws of physics are repealed.
Stability and response are mortal enemies. A drag bike or a Bonneville Liner are stable, but they are not responsive. A Trials bike is very responsive, but it sacrifices stability to achieve it. You would not want to thread a bike with a Top Fueler's geometry through an observed Trials course. You would not want to ride a trials bike at 200 MPH. So you can very easily have either too much stability, or too little, it all depends on the function of the bike.
And everything in between a Liner and a Trials bike is a compromise. Longer wheelbases increase stability and decrease response. A large polar moment of inertia increases response and decreases stability. Big tires increase stability and decrease response. And, as sure as BMW makes crappy final drives, increasing trail increases stability and decreases response. And adding offset does not increase trail, it reduces it.
So what are you feeling? Who are you going to believe, your own experience or that tosser Jinx? Well, to start with, I would appreciate it if you would stop calling me a tosser. Thank you. And secondly, there is no real disagreement. Because we are now at what matters most, what all these little measurents are supposed to produce, And that is rider comfort.
And by rider comfort, we are not talking about a better seat. We are talking about whether the stability/response trade-off matches your riding style. You can make a bike too stable, particularly an off road one. Excess trail will lead to a stronger corrective force every time the front wheel points anywhere but dead ahead. So is this bad? I t certainly can be.
Say you are riding a trail at a fair old clip. the surface is hardly smooth and level, therefore your front wheel will be constantly reacting to that surface and rarely pointing straight ahead. Now, with too much trail built into the geometry, every time one of those little irregularities pass under your front wheel, the corrective force will attempt to make the wheel turn back to center, And you will feel this a series of very annoying left/right jerks through the bars. Which reduces rider comfort as to how well the bike can be controlled. There is too much stability, not enough response, and the whole thing feels very mucked up and unpleasant.
Same thing with sand. Too much corrective action from the steering geometry will prevent the tire from following the surface naturally. It will try and maintain one arc regardless, which is felt as that dread "knifing" feeling.
An F22 is unbelievably responsive, but to attain that is it so dynamically unstable that it will literally break apart in the air if it were not for the flight computers constantly adding just enough stability to maintain controlled flight and structural integrity. And a good steering damper is our less-than-$30M answer to a flight computer. It adds enough stability, on demand, and otherwise allows a very high level of response.
So the correct term for increasing offset is: It makes the bike handle better. It feels better so you say it is more stable. But it is not, it is just better balanced now between stability and response to make you more comfortable. Which feels like stability, but isn't. Words matter, and so do all those little numbers. And you can look it up for yourself if you don't want to take some tosser's word for it, but increasing offset reduces trail and reduces stability. But it might well feel better that way.
So increased offset may be just what the doctor ordered to allow you to gas it up in confidence, and that is what the whole deal is really about. And this is probably where people like Emig (and others) are invaluable. They know what works. But I would die a happier man if they learned how to explain it correctly. Cheers.
