| Author | Message | ||
     Ferrisbuellersdayoff |
You seem you be the suspension man. I got me a used owners manual and tuned the suspension to my weight and road conditions. I'm 175lbs, and I set the little screws for more comfort, less sport. The whole bike wobbled at turns and was all squishy. Should I tune it for a heavier rider weight or for more sport less comfort? | ||
| Slaughter |
First question - tires: Which tires, what pressures and is the rubber fresh? Second: How many miles on the suspension? Sometimes the beasties get seals worn and damping goes off - also if the oil is old, it doesn't damp the same. I have a couple articles (I really ought to get them more up to date) but they are pretty good for basic suspension trouble shooting. PM me through my profile, I'll send them to you. Also, you are almost exactly my weight so if you're using stock springs, you should be able to dial in the bike. We have the same basic bike. Kinda tough over the 'net - but it MIGHT be that the preload/sag adjustments are slightly off. First - you're better off setting sag by direct measurement, not lines on the adjusters - needing about 35mm in front, 25mm in rear for start. You get it by lifting the bike off the ground and measuring from a fixed point down to the axle - this is "ZERO" - next sit on it with ALL your gear. Wiggle and bounce a bit - measure this point down to axle. The difference should be about 35mm front and 25mm rear. It's only a starting point. Next is damping. You probably ought to start out first with "comfortable" damping settings and then "sneak up" closer to the "aggressive" settings. You have the "Higbee Tables?" They're here around on Badweb somewhere. REally good for starting damping adjustments. (Message edited by slaughter on January 13, 2008) | ||
| Slaughter |
One of the best series of articles written on suspension setup http://www.sportrider.com/tech/motorcycle_suspensi on/index.html Again, using Higbee's guides and if your tires are fresh and properly inflated (NOT inflated to manufacturer's recommended pressures, by the way) and if your suspension has fresh oil and good seals, you can get it pretty close without a whole lot of pain. This is fun stuff - and assuming you don't have good access to a race track, you do need a road that you can consistently run pretty much the same speeds through the same turns a few times before making SMALL changes. | ||
| Slaughter |
If you are going to rebuild your forks, just throw out the stock dual rate springs and get a set of 0.95 kg/mm springs - available from many sources:  (Message edited by slaughter on January 12, 2008) | ||
| Ferrisbuellersdayoff |
Last week when i rode it, everything was fine, tires were at 19PSI, so i aired them back up to 39PSI(sidewall said 42PSI) Therider weight was set for like almost 300lbs up front. andf the rear spring ramp was on the 4th notch I dropped it to the 2nd. The bike has 9500 miles on it, I got it at 8800. I made notes on the previous settings. | ||
| Slaughter |
I'd be curious to know which tires you are riding. Those pressures seem SCARY HIGH. GENERALLY (very generally) speaking if you're wanting the bike to handle well, starting pressures are more like 30-31psi (cold) for pretty aggressive riding. Again, that varies with manufacturer (Michelin being notably different in a couple designs). The 30-31 numbers are based on Pirelli Diablo, Diablo Corsa and Dunlop D208. If you were racing, you'd even start out lower yet. The factory recommended pressures are for tire life and NOT for handling. I don't even know what is printed on the sidewalls, those pressures don't make sense. With pressures set for handling (not rubber life), you will burn the rubber off in about half the miles. If you are working on setting the bike up for handling, it will mean lower tire pressures to start with. Again, I haven't run Michelins or Bridgestones and so can't really comment on them but pressures for certain really need to be looked into first. Doesn't sound like you have tons of miles on the suspension. More suspicious about tire pressure than suspension settings. Remember, NEVER change more than one thing at a time and then ride it quite a few times through the same set of turns before deciding that you need to change anything else. YOu have to sneak up on suspension a bit. The experts are much better at it. | ||
| Ferrisbuellersdayoff |
Pirelli Diablo Strada | ||
| Slaughter |
Looked at the recommended pressures for street - front at 32, rear at 36 and only based on the same "recommended" pressures by the factory for the Dragon Supercorsa (racing) I would recommend starting the front at 29, rear at 31 (cold). I actually run 26 and 28-29 on the racebike - again different tires but same recommended pressures. If you are going to be just riding highway and NOT doing any hard turning, you can pump them back up to the recommended pressures but pumping up to the full recommended pressure is going to make for bad handling. If you change tire pressures, DO NOT make any suspension changes until you've run a half dozen run at same speeds through same set of turns so your brain gets "imprinted" on just how the setup works before making the next change. You need to be able to "feel" the effects of small changes and that is impossible without hitting same turns, same conditions, same speeds. (Message edited by slaughter on January 13, 2008) | ||
| 4cammer |
Front 29 and rear 31.... I have always run what the manual states. Can't wait to try this out. Only two more months till riding weather here in the Chicago area. I need to get me a winter bike..... | ||
| Ferrisbuellersdayoff |
more like a winter home | ||
| Doerman |
I will defer to what Steve is saying here regarding setup. But there's one thing that does not square with my experience. For street riding I have found that the recommended tire pressures (owner's manual) work very well. I found that out the hard way the other day.I took the 1125R to the dealer to have them swap the muffler since I got a 49 state muffler for mine. Part of the regime at the dealer is to check everything (including tire pressure) before they give the bike back to the customer. On the way home I thought the front end on the bike felt vague and sluggish. Once I got home I checked and the dealership had set it to 28 front and rear. I changed it back to what the manual states 35/34 F/R and that gained back the crisp and clean handling I had before. I don't know how that figures in here but FWIW. Asbjorn | ||
| Slaughter |
Tire pressures are still not going to solve the handling issues that Charlie (Ferrisbuellersdayoff) mentioned. It really sounded more like preload/sag - and secondarily damping. I was just trying to get my mind around how the bike was set up to start. People forget that as the oil gets old, the damping changes as well as with seals wearing. Without actually being there, it really MUST be done "by the book" - suspension tuning really takes a number of weekends at the track - even more if all you have is the street. Higher pressures - as in the recommended pressures - just mean less traction when leaned over. You're right though, still won't account for the squirrely feel he was talking about. Really, suspension tuning with a professional right there trackside depends on detailed inputs from the rider and the suspension guy looking at the tires - how they're wearing, how the bike is exiting the turns under power, how it is handling going in while braking (trail braking IF the rider is comfortable) Kinda really very difficult to troubleshoot online. That Sportrider.com series (linked above) is a really great introduction. The Higbee tables are an excellent way to get the bike close from the start - but the rider still has to pay close attention and make really small changes. I still use trackside suspension vendors - I should say WILL USE when the bike gets back together in a couple months. We have an excellent suspension guru at Willow Springs who will spot you just as you exit - check tire wear, measure tire temperature, check HOT pressure... and make recommendations based on your input. Not trivial but it sure does make a HUGE difference after a couple months of work. Sometimes a "wobbling" feel can come from a rider not hanging off and having too tight a grip on the bars. Just a lot of variables - but getting the basic setup down is critical. (Message edited by slaughter on January 13, 2008) |
