| Author | Message | ||
     Ejiii |
Greetings, Just had my front forks revalved and resprung with Ohlins components by PPS (Stig Pettersen) of Anaheim, CA. Can't wait to test it all out but need some help. How many mm of front suspension sag should I be looking for? Thanks in advance, E. J. | ||
| Slaughter |
I've heard nothing but good about Stig. Call him right back and ask him - also get your starting damping settings for compression and rebound... seriously. Stig is about as knowledgeable as anybody. Otherwise, you CANNOT use the book settings after re-springing and re-valving. If NOTHING else, you can start at 35mm static sag in front and about 1/3 damping (leaning toward starting from "too little" damping - and sneaking up on it a quarter turn at a time based on how it responds) Best thing though is to ask - I'd bet he can tell you almost exactly what you'd need. (Message edited by slaughter on May 27, 2007) | ||
| Kds1 |
Ej, what Slaughter said 35mm front and 30mm rear.....the damping adjustments will be depending on your riding style and road or track conditions....give me a shout if you need my help, I'm getting real good with suspension these days..... Kevin www.kdfab.com | ||
| Ejiii |
Hi Guys, Thanks a million. Stig is the man! I just couldn't get back to him before he was gone for the holiday and wouldn't you know we talked about everything else when I picked the forks up on Friday but sag settings. We got the comp/rebound set at a starting point and I'm sure he got the preload set for my weight etc in his shop. He has some way of doing that on the bench. My current sag with the new set up is 28mm, that's with out all my riding gear. I figure all suited up, (Aerostich Darien jacket/pants and combat touring boots), I'll fall somewhere very close to 35mm. I need to go play, I just wanted to be sure it was somewhere close before I went for the road test. Thanks Again, E. J. | ||
| Gentleman_jon |
EJ, Glad to hear that you are good to go. Without wanting to highjack a thread, I would like to see a more illuminating discussion of the theory of suspension set up, especially for the Buell. Normally, suspension set up discussions start and end with preload settings, and compression and rebound adjustments. As many have pointed out, preload settings are really just an analogue of the actual sag settings. People like to refer to them because they are easy to set and measure. And as important as sag is as a measurement of available suspension travel, it is often used as an analogue of attitude settings, because the ride height, on the Buell at least, is not really adjustable. Thus the really important elements of handling, namely fork angle and trail, and the relationship of the swing arm pivot to the axle height, are unknown, and for the average mechanic, unknowable. These are the measurements that are used when the bike is actually designed. I recommend putting marks on the front and rear of the motorcycle so that attitude can be measured at least, but this is only useful where an aftermarket shock with adjustable ride height has been fitted. I mention this because I have heard a wide variety of " correct" sag measurements ranging from 35mm front and rear to 25mm rear, 30 mm front, ( Slaughter, I think:-). It would be great if anonymous or some other expert could chime in, and shed some light on these sacred mysteries. I guess the proper way to set up a bike would be to know the proper attitude, then select springs according to the riders weight. Then sag would be set on the basis of available suspension travel, with preload. I am guessing that with the idea spring, not much preload would be needed. Then attitude would be set by adjusting ride height front and rear. Finally damping settings would be done to suit the riders style and prevailing road conditions. Can any one shed some light here? | ||
| Ridrx |
I too would like to be enlightened about the "proper attitude" scenario. Suspension settings(aside from spring rates) are very subjective to begin with, so getting advice is difficult...everone likes something different. I have heard, and seems to make some sense, that the static(w/rider)r.sag is usually set to around 30mm street/25mm track(provided your spring rates are correct for your weight), and the static f.sag was used to determine the pitch or attitude of the bike depending on how far fore/aft the rider carries their weight and whether you are tuning for quick turn in or high speed stability. ...any truth in that at all? (Message edited by RidrX on May 28, 2007) | ||
| Wantxbr |
On the money Ridrx. Heres an article that will give step by step instructions for setting up you suspension. It is still rider preference though. Don't expect to like the feel or ride of your bike if you follow the article. I found I like just a bit more sag than they state in the article. http://www.sportrider.com/tech/146_0402_susp/index .html (Message edited by wantxbr on May 28, 2007) | ||
| Ejiii |
I am far from a suspension expert but here goes: I think we all know ride height should not be adjusted with spring preload. Front ride height on the Buell can be adjusted by moving the forks up or down in the triple clamps. Rear ride height is non-adjustable with the stock shock. Gentleman_jon, of course your Ohlins has a ride height adjustment (I'm gonna get me one!) Ideally, we would all have suspension springs set to our individual weights then preload can be set very accurately with sag settings. Race-Tech says street bikes should have 25mm-35mm of front sag, race bikes 25mm-30mm sag. Those are generic specs but from what I have seen they are pretty darn close. My current set up with full riding gear is between 30mm-35mm. My first test will be the commute to work. On 6/10 I'll be on a club ride through the canyons of Malibu, CA. That will be the real test, about 150 miles of super tight roads that are worn out! Yee Haa! | ||
| Wantxbr |
Your ride sounds like a blast! I love Race Tech, I use there fork emulaters in my Dynaglide. WOW what a difference they are I even like them more than the FXDX adjustable front forks. There also a great place for info on suspension. | ||
| Ejiii |
Yes, Race-Tech is a great source for parts and tech info! Here is some information from Stig I thought you would find interesting. For street sag he suggests 35mm-36mm, for track sag 38mm. I'm currently somewhere between 30mm-35mm. I need to get a buddy over to help me get a real good measurement, I was using my wife for my helper this go around. | ||
| Ridrx |
Ejiii, Funny how one source recommends less sag for the track while another recommends more. It would make sense to me that a suspension works best in the middle of it's range of motion. If your suspension has...say 6" of travel topped out to bottomed out and your riding habits/conditions only use a portion of that...say 3", then wouldn't you want that 3" to be in the middle of the overall travel length to achieve optimal damping control? IF that is the case, wouldn't that be a dictating factor in preload adjustment? I hear people say not to use preload to adjust ride height, yet I wonder...if you have linear/constant rate springs, what exactly does preload do besides change ride height? Obviously I know little about suspension, but it is fast becoming my favorite topic...such improvements from the twist of a few knobs (read:FREE) is right up my alley. | ||
| Ejiii |
I agree, one says less someone else says more, who knows! What makes it even more confusing is the sources are credible! So it goes. On my forks Stig focused on reducing stiction and getting full use of all the travel. It sure worked good today. Now the rear needs to be done! To my understanding the general rule is, of your total travel 1/3 should be sag. In the 6" example sag would ideally 2". | ||
| Slaughter |
I've collected a few articles and I've put them into MS Word format. They're pretty useful for fine-tuning your suspension... along the lines of "if your bike does ..blank.. when you do ..blank.. you need to either change the ..blank.. or the ..blank.." When doing detailed tuning, you're really sneaking up on settings. Email me and I'll throw you the articles. They're around here somewhere. | ||
| Slaughter |
...and I need to mention that the MOST IMPORTANT TOOL in setting up your suspension is a notebook - and a set of turns that you can hit over and over and over again in the same conditions. Not everybody gets access to a track and track days. Failing that, you just need to pay close attention to how your bike is responding. | ||
| M1combat |
"Then sag would be set on the basis of available suspension travel, with preload. I am guessing that with the idea spring, not much preload would be needed. " Always keep the law of diminishing returns in mind. In this particular case if you use too much preload (fewer lines showing) then the front of the bike will get twitchy exiting turns (mostly just second/third gear turns on an XB that doesn't have more than stock power). You don't want to be exiting turns with the front suspension topped out before you're pretty straight up. You've just got on the throttle exiting a turn and your front suspension tops out... it gets twitchy. You'll also sacrifice turn in due to the bike not pitching forward as much which steepens the rake angle. Not enough preload will cause the steering to feel very heavy (/EDIT - But stable) on the brakes. Set the rear preload at it's highest setting and enter a turn without using the rear brake. Notice the effort required to get the bike to flop over. Now take a notch or two out and do the same thing (or use just a tad of the rear brakes  ) and the bike will roll in a bit quicker with the same effort at the bars (or the same roll rate with less effort). You're right in stating that ride height is better adjusted with fork level but the correct mixture of fork level and having the proper preload for the situation is the best thing. If you really want to get deep into it... Start thinking about what fork OIL LEVEL does  (Or... More correctly for pondering purposes... The volume of air in the fork). That's the front.... The rear doesn't need as much sag because it just skims the ground under heavy braking anyway. What it does need to be able to do is lower the rear of the bike AS you're getting on the front brake so the front brake is more effective and then NOT extend too far when deep into the braking zone that it changes the suspension geometry dramatically as you roll in... The rear rebound setting is quite important for getting a good drive out of a turn and for getting on the brakes later. It needs to work well with the front rebound setting. I hope that made sense??? In any case.... It's not a good idea to finely tune suspension for the limit on the street. Tune for the limit on the racetrack because that's the only place you'll see the limit. Keep in mind that you aren't tuning to the bike's limit... You're tuning the bike to work well with YOUR limit. It doesn't matter who you are... the bike is more capable than you. It's better to tune it so the bike is recoverable in adverse situations. Things like losing the rear going into or coming out of a turn, making sure it's giving you lots of feedback so you know what's happening, making sure it doesn't just let go on you etc... A good race setup is not the same as a good street setup WRT both preload and damping. You'll want a bit more sag and a bit less bump damping on the street. I think rebound should be roughly the same. One more thing... I would do no less than 50 hard miles or 20 laps between changes unless there's something horribly and obviously wrong. Also... Yeah ... get a notebook and use my advice at your own risk. I'll take no responsibility for someone jacking up their suspension. If you want safe... use what's in the manual . Ok one more thing ... you don't actually want to find the limit because there's only one way to be exactly sure where that is and that is to exceed it. Pay your insurance and hug your kids every time you ride . (Message edited by M1Combat on June 05, 2007) |
