M1Combat

If you have traction available you could start adding speed and the bike would begin to stand up? You could lean your upper body further into the turn to lift the bike a hair and use the extra traction to feed in some power?

The "COMBINED" CG height will be exactly the same height (given equilibrium) no matter where YOU are on the bike given the same speed and radius. Hanging off certainly moves YOUR CG to the inside of the corner (but moves the bikes out a little...) and the COMBINED CG stays at the same height. One would want to pick the bike up off the edge of the tire while coming out for a couple reasons... One, you want to save the edge to maximise mid-corner speed through the race. Two, you can put more power down when the tire isn't right on the edge. Three... (this ones a little tough to follow for some) the tire is smaller the closer you get to the edge... This means that when you roll over to the edge, if you keep the same speed, your RPM's will rise... You can use that extra HP WHILE picking the bike up to help add drive out of the turn... If you're in an endurance race you MAY be able to save a bit of fuel by hanging way off and using the larger portion of the tire. That is... if the extra wind resistance isn't offsetting the fuel savings... Each tire will have a lean angle where it will generate the most grip. You want to use THAT lean angle mid-turn as far as I know. To do that AND go fast/er, you hang off which lowers the combined CG and will require more centrepital force (AKA Speed) to achieve equilibrium... You hang off just enough and use just enough speed at the "right" lean angle for your tire/setup/geometry/etc combination to maximise grip... Or at least that's how I see it, but I've never even done Code's L1 class... I'd LOVE to, but I have more suspension and motorcycle to buy before I can get on the track as well as in school. School will come before track, but I will be using the school AND track days to get a setup started so I may as well start with the suspension I'll be using on track... In racing, EVERYTHING counts. It's all about energy management.

I've heard it said that when Michael Schumacher closes his eyes and visualizes a single lap... He opens his eyes typically within a hundredth of a second or two of his typical lap times.

In my humble experience... It seems to me that Dunlop tends to make a rear tire that has a somewhat flatter profile than the competition. It works well coming out, but sacrifices some mid-corner effectiveness. I think your problem would be completely solved by hanging farther off the bike, or moving to a 180, or going to a different brand. A pound less pressure in the front may help as well?

Sounds about right... Which would be why it's called "Anti-Squat" as opposed to "Pro-Lift" .

The entire bike lifts. The important part of geometry that has the affect is the relationship between the rake angle and swingarm angle. The rear wheel moves in an arc, the front in a straight line. As you get on the gas you want the wheelbase to stay the same. You need what they call "anti-squat" on the rear. The axle and swingarm pivot are the important points (along with the action of the chain). If the axle is lower than the swingarm pivot point, then the force applied in a forward direction will attempt to push the swingarm under the motorcycle. Due to the fact that it's fixed at the front, it will rotate. It rotates downward. This lifts the rear of the bike. The key is to try to keep the wheelbase as static as possible so the steering geometry doesn't change as you apply power. Two things change when one end goes up/down more than the other... Wheelbase and rake. The less these change, the easier it is to keep the bike near/at it's limit. It's why I hate peaky IL4's . I'll take an engine with linear power over one that's peaky any day of the week.

I didn't say "Buell". I said "Buell XB". If you haven't ridden one... well... Just keep talking out your ass then I guess. 20K miles and only one issue. The trans output shaft seal failed because I dropped it into first w/o the clutch TWICE from a dead stop. It just seeped a little and the dealership replaced it under warranty (a two year warranty I might add) in about 40 minutes. No trouble other than that. Besides... This is a thread about handling... What's the deal with coming in here and talking about a niche market sport-touring bike? You brought it up though... The S2/S3 bikes are a good handling bike for touring bikes. I completely understand that Buell went through some growing pains but AT LEAST THEY RECALLED STUFF. Other companies have FRAMES that crack and they refuse to admit it... The XB's have had two recalls in four years. Both on the first model. One was for the wheel bearings, and the other for the kick-stand. Both were supply issues as opposed to engineering issues. The parts were recalled/replaced for free and BMC made a good effort to actually contact EACH AFFECTED CUSTOMER to let them know. Just an FYI... Based on warranty dollars spent per unit sold... The XB series is THE most reliable motorcycle money can buy. I understand that none of this will change the sour taste in your mouth. Sorry your S2-"T" (Please note the "T" there...) handled like a "T"ouring bike . Aside from that... Recalls are recalls. They happen to lots of bikes. It's the companies that WON'T recall stuff that really suck. You think just because a company refuses to DO recalls that the engineered a superior product? Keep thinking that .

I think what I do is most like what Woody describes. Sort of throwing the bike around under me with my knees. Both knees on the tank in the center, and then sliding out to one side as the lean angle goes up. Of course this is only between turns in a chicane type setting. For your average "single turn" I get off the bike a little ways before I get on the brakes and stay there until I'm at WOT coming out.

You can corner just fine with the front in the air. That said though... If you ARE cornering with the front in the air, you're leaving a lot of speed on the table and you weren't at the limit to begin with.

I agree . I have a passion for Buells. Just to keep you up to date... Jeremy McWilliams, Mike Cicotto, Pascal Picotte and Rico Panzkopher will be riding Buell XBRR's in the 200. I think they'll have a fighting chance but of course the teams are somewhat new to the Daytona. Mike Hale may be in it too, but Innovative's team may not get a bike soon enough. Here's to hoping though. Try a Buell , You'll like it if you like bikes that handle well.

Watch the Daytona 200 .

I've never been on a purpose built race bike, but I have a Buell XB12R and it seems to handle very well. It seems to be one of the most capable handling bikes made (right up there with the 999R, 916, 749R and RSVR) and it seems very easy to access. It seems very stable through high speed sweepers over bumps with no damper, it is VERY flickable and responsive (as it should be with 250GP like geometry) and the low reving V-Twin creates a power band that is easy to access and has no suprises. I'm sure I'll get a few heaters for this, but I think it's the best handling production bike man has devised. The thing is... Buell ships the bike with tires that don't seem to be matched well with the radical geometry. With the stock tires it wants to stand under mid-corner braking (not so much if you're just trailing a little rear brake) and it takes (IMO) too much effort to the inside bar to keep it leaned over near the lean angle limit. Swap out to Sportecs, Diablos, Qualifiers or Pilots and both issues disappear. When Erik Buell is asked about it he typically responds that there aren't enough Shawn Higbee's in the world. I would tend to agree because I've learned that proper form eliminates these issues as well. It's just that hanging way off and being a stickler for form all the time isn't practical. When tearing up canyon roads, sure... but sometimes I just want a moderate pace. I also didn't like the wet weather characteristics of the stock Dunlop tires. Mid-corner line changes are effortless and it's been proven many times that the XB frame is capable of higher mid-corner speeds than just about anything else out there.

I think the problem that we may be running into is that IMO there isn't a "answer" to whether the CG should be high or low. I think it depends on what you want out of the bike. I think a bike with a high CG will feel like a "light steering bike" and a low CG will feel heavier. The "answer", as I've said before, is that you define what you want the bike to DO first, then you go about getting there by tuning rake/trail, CG height, wheelbase, angular relation between the swingarm and rake, bar leverage, frame stiffness, seating position, suspension setup, wheel size, etc, etc, etc... The ONLY other thing we can do IMO is decide what the effect of raising or lowering the CG is when leaving everything else alone. That said... I ride an XB12R. It's widely regarded as one of the best handling bikes you can buy (like top three, and most places put it AT the top, but really , I'm not here to bench race ) and it's got one of the lowest centers of gravity of any production bike and it's mass is EXTREMELY centralized. It also has a very steep rake angle and very little trail and heavy flywheels when compared to most other bikes so I really can't tell you which of those is "most" responsible for the good handling. As I said above though, I suspect it's the entire package... In any case... The roll center should be between the combined CM and the bikes CM... Probably very close to the bikes CM. It would make sense to do it that way because that should allow the bike to be as light feeling as possible because it's rolling around a spot very close to it's own CM. I really wish I had the right books to read...

Interesting... I was looking at the running man from a completely different direction... I would ass u me that that fulcrum is where you trip him and the end of the lever arm would be his CM. The fulcrum is also the RC (ass u ming a rigid skeleton...).

WRT the higher CM making it "easier" to initiate lean... That's all I was saying . Not that it would also be inherently faster. The fulcrum would of course be the roll center. Look at a teeter-totter... the fulcrom is the roll center. Of course, ours isn't attached to anything in particular, but it's there. "With a human low and long as recommended by the experts for turn in/cornering....just where do you figure the cm to be? Up high on top like a sledgehammer balanced on the end of its handle? Really?" No. My guess would be just a few inches above a line drawn from the top of one tire to the top of the other in side view. I certainly see your point with the two handled hammer thing but it didn't serve the purpose of the point I was trying to make. I wasn't assuming that the RC of the hammer was at the hammer head. "I agree with tzrider who said something about easier not being the same as faster." Me too . "And...at the end of the day, what if the centralization of mass might be the defining parameter for turn in speed." Centralization is obviously important but of course you'll run into the law of diminishing returns with that and the gyroscopic properties of the crank shaft will need to be looked at as well. That said, it's all a trade off. Larger flywheels add stability. It's all a package... Which is why I think that "at the end of the day"... The CG height needs to be placed where it needs to be placed to maximize traction when leaned greater then 45 degrees. I could care less about "lever effort". I care about quick. That's why I ride an XB12R. It is a little harder to snap into lean at higher speeds, but it does it very quickly if you use your muscles. It's still a whole package though... radical geometry for sharpness, large flywheels to stabilize, VERY centralized mass etc... "So, the longer the arms, the less effort needed to initiate spin. But the slower the roll/spin will be. The shorter the arm(s), the more effort needed to initiate spin. But the faster the mass will roll/spin. The closer the cm is to cr, effectively speaking, the shorter the arm(s) will be. " I would agree with those three statements. There's still a fine line though... You don't want a bike that takes so much lever effort that it becomes difficult to manage the strength that you exert, or makes you prone to using both hands to initiate lean. "So...where is the force applied? Is any applied at the top? Or the center? Or just at the patch? Hmmm..." At the tire patch obviously, but also from the top (your other arm ). We "should" hang off well before we initiate turn in. This gives gravity a longer lever to pull the bike over using our mass. Forces applied in the center... Twisting forces I would imagine. Torque applied to the frame by the steering head and running through to the swingarm. "hey, why do stock cars and sprint cars run speedways counterclockwise????? " Because most people find it easier to turn left.