| Author | Message | ||
     Stevek1125r |
I just installed New Pilot Pure tires (i love them BTW), a GPR dampner and Erik Buell RacingR Finned rotor. I also installed EBC HH pads and i used a new rotor hardware kit from Erik Buell RacingR. I know i installed everything correctly. i have already quadruple checked everything. Under HARD braking (on the verge of pulling a stoppie) the rear gets light of course and then starts to sway back and forth. Now i will admit the new GPR dampner took a minute to get used to, but i like the feel of it better. maybe this device is causing my issue? Its just weird that the bike' tail sways back and forth.. it reminds me of a shopping cart caster when its going to fast... Thoughts? I haven't touched the suspension since last year so it should not have changed. maybe i should go back and double check it. | ||
| 01lightning |
whats your tire pressures? | ||
| Avalaugh |
With the GPR damper fitted I'd take a guess your not bracing with your arms as much, causing the rear to side step a bit more than usual. | ||
| Skntpig |
Everything sounds right. Mind over matter. If you don't mind, it doesn't matter. I think you are just braking hard and the rear is getting light. You may be able to minimize this if you get suspension settings dialed in. | ||
| Jdugger |
A wagging rear under really hard braking is somewhat common, honestly. Check out this video at 1:54: http://www.youtube.com/watch?v=PKxrp0IhHu0 | ||
| Dannybuell |
add some more preload to the front. less forward weight transfer might help some. please let us know what you end up with. | ||
| Nattyx1 |
also are you gripping the "tank" with your knees when hard braking? (good) Or are you just doing a pushup and standing on the pegs (bad). If the latter, the wiggle is almost certainly caused by the fact that your dom arm is way strong than your other arm. You push HARDER on that side, the bike starts to lean as you enter the stoppie. you subconsciously shift your weight as you feel that to compensate, the bike sways back, so you push again, etc. It all happens in an instant because your reactions are subconscious. Lock your lower body to the tank, r-e-l-a-x your arms and use your hands not for handstands but to gently hold the bars, and concentrate on only putting sufficient pressure into the lever to make the bike stop at the rate you choose (WITHOUT pulling the right side toward you as you brake). Also, do what danny said with the suspension, plus you might wanna try adding some rear rebound also to slow the rate the tail springs up when the weight transfers forward. the gpr, set below 3, will only make the bike better, all other things being equal. | ||
| Rodrob |
+1 Nattyx1. Too much weight on the bars. But I am confused about the rear rebound. I've been told to loosen the rear rebound so that the tire tracks better under light loads. Did I miss understand? | ||
| Nattyx1 |
rebound controls the speed with which the rear end reacts to bumps... rear spring controls ride height. the spring WANTS to extend and the rebound controls the speed with which that happens. So too much rebound damping, you hit a bump, the rear is too slow to react, the bike bounces over and the tire doesn't track (your model as described). Too much compression damping can cause the same problem as it acts like the spring does on impact - essentially an "initial bump impact deflector" --- but then once the impact is over, the spring takes over the work and the rebound damping controls the spring. Got it? So too LITTLE rebound damping, when the weight shifts off the tail on braking will let the spring unload too fast and you get this vertical boing from the back as it tries to catapult you over the bars (essentially - I'm describing the sensation, not what will actually happen, ok?) AND that makes you also FEEL like your braking harder than you actually are... and THAT increased sensation of emergency deceleration scares you (not just YOU) and so you brake more gently, hold em on for longer, and other racers will beat you to the apex... and your lap times will go up accordingly. Get your stuff settled so your throttle and brake inputs create the least possible upset to chassis attitude (while still allowing the tires to track and not chatter or skip). Brake late and very hard initially in a straight line and ease off as you trail off the brakes toward the apex (opposite of pure street riding braking where you ease INTO the brakes and add pressure because it's safer that way), and if you've done your setup right and you're not adding unwanted inputs to the bike (via handstand or foot pressure or ass wiggle), you SHOULD feel your speed changes are SOLELY that, and have what feels like zero effect on handling/traction. Now you can always overwhelm best-possible setup with superhard braking. It's called a stoppie - your weight transfers so fast the ass leaps in the air. Fun for stunting. Bad for track. Or you can cause the front tire to skid, or both. But you're not gonna do that because you have a smart right hand, correct? :-) This guy makes a lot of money doing this. You'll just end up with a neck injury.  | ||
| Rodrob |
Thanks! | ||
| Froggy |
Thank you, I had the tail wag happen once during some high speed panic braking, but I didn't think anything of it. I guess I got me some more learning to do  | ||
| Dannybuell |
Nattyx1 - good stuff. | ||
| Jdugger |
> I guess I got me some more learning to do I think we all do. I'm less concerned with it than Natty, mostly because I don't see a way around it. I get the wag in intense braking zones, and often I just have to deal with it by reducing brake pressure or just getting the bike leaned into the turn and waiting until I feel the rear grab before getting the gas. A lot of it in a track situation is simply because you need to (or, rather, I need to) have your body already set up for the turn, and two-knees-on-the-tank just isn't realistic or practical. You are grabbing handfuls of brake, picking up gears, getting a turn in accomplished, getting your body off the bike and ready for the turn, all at once, and wag happens. If I got wag on the street, I'd be changing my diapers. | ||
| Stevek1125r |
I will admit i do not have the greatest posture for riding. I know i put to much weight/pressure on the bars. I did get the tank grip kit from American Sport Bike and those things HELP A TON!. I try to remember to grab the tank with my legs before hard braking but its not second nature yet. Good to hear i'm not the only one with tail wag... I guess i need to tweak my suspension a bit more. thanks for the input guys.. Keep it coming | ||
| Stevek1125r |
tire pressure are 36 F/R.. btw | ||
| Lovedabueller |
I like the tail wagging....breaking hard...down shifting and feeling the back end start to slide is FUN!!!!!!!  | ||
| Stevek1125r |
Not a straight line on the street, it causes panic in drivers around me.... i feel they will be more inclined to watching my tail wag and not remember to stop, just as they run me over... | ||
| Blake |
Rear wagging under extreme braking is no big deal. Ask Ben Bostrom. | ||
| Geforce |
We sat near the end of the track at Road America and watched every single bike that entered the chicane start to wobble from the rear... they were braking hard, wobbling, and then accelerating and wobbling. Seemed to me at the time that it was the general consensus to brake and accelerate hard pushing the rider and bike to the limits of traction...in a race. | ||
| 01lightning |
i wag at the track frequently....reading your original post I was under the assumption that you had not wagged until you put the other tires ,rotor and damper on. Great points Natty,Rodrob and Jdugger, but why now? If it were a rider issue, why hasnt it surfaced before putting these components on? New Pads grabbing more aggressively maybe? not doubting you guys-just wondering | ||
| Jdugger |
Skills improve, needs from the chassis change, changes to components may highlight these things. ... and so on. If I had the answers to the why now question, I'd not be spewing my worthless advice on a forum, but probably be a head tech on an AMA team | ||
| Nattyx1 |
Don't sell yourself short, JDug. You're a thoughtful guy and unlike lots of newer racers, you do seem to have a good feel for what's happening underneath you. And 01Lightning: Jdug's right... and add in the variables of tire adhesion, track ripples, road camber, how tired you are or are not... all factors in whether and how much "wag" one gets. Ultimately it's only an issue if you're setting the bike back down crooked which, when the rear sets and hooks back up, pushes the front in a way you didn't intend. Good racers are always either ON the gas or ON the brakes. So managing those transitions is the actual skill everyone works on -- whether you're talking about the rider, the suspension guy, the electronics guy, the brakes guy, the tire guy. Everyone is working to improve the fluidity of stepping through that simple-sounding 3 part process: off gas /on brakes / off brakes / on gas, repeat. This is the "hard" part. Turning the motorcycle is easy once you get this stuff handled.  (says the mediocre ex-racer...) | ||
| Stevek1125r |
01lightning, this is COrrect, i never experienced Tail wag until NOW..... the Old setup was all OEM stuff. Added the aftermarket stuff and now i feel a bit of wag. After riding again today i noticed that when i concentrated on not having so much pressure on the bars the wag was less.. I guess i need to go back to the Gym... My normal diet of 12 ounce curls has long been over with for nearly 9 months now. (no drinking on the dirt) looks like i need to start again... Not while riding of course. | ||
| 01lightning |
right on! this is a great site aint it? Sounds like NattyX1 may have remotely solved an issue! when I was in advanced rider training(basic) the instructors did this really cool demonstration...well maybe not cool, but really opened my eyes. One instructor was on a bike on a stand going over body position. He was simulating a turn-butt cheek off,knee out,opposite elbow resting on the tank...then the other instructor knocked the 1st instructor's hands off the bars but he stays in position-demonstrating the light 'grip' on the bars and how he was supporting his position with his core and his legs. That really helped. Actually, thet was in ART basic, my very first track day. Great info. | ||
| Jdugger |
> Good racers are always either ON the gas or ON the brakes. +10,000,000,000,000,000,000,000,000,000,000,000,00 0,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000,000,00 0,000,000,000,000,000,000,000,000,000,000,000,000, 000,000,000,000,000,000,000,000,000,000,000,000,00 0,000,000,000,000,000,000,000,000,000,000,000,000, 000 Ty Howard always teaches: "There are two ways to control the speed of your motorcycle, the throttle and the brake. So, you are either using one of those controls, or you are OUT OF CONTROL." | ||
| Ratbuell |
(says the mediocre ex-racer...) Um...I call bull$hit. I've tried following Steve around a track. A couple times. He makes outstanding points...and I've seen him put them into practice (from a distance...waaaaay back behind him LOL). I just wish our roads were clear enough in Maryland for me to actually PUSH the bike a little in turns. I feel like I'm going to lose what little 'edge' I might have had at the end of last riding season! | ||
| Blake |
On the gas or the brake... Very true, but there are some instances where lack of traction dictates rolling off the throttle with no application of the brake. The MotoGP guys, most of them, were all letting off for a bit as they flew over turn one at Laguna Seca. Turn one is a slight left with apex atop a rise, for all other motorcycles, just an interesting feature on the main straight. But the MotoGP big literbikes were getting very light there. All but one through qualifying, Nicky Hayden, were rolling off through turn one. Nicky kept it pinned. I was fortunate to be standing looking down the straight from the exit of turn one. Absolutely incredible sight to see. One of the best racing spectator memories I have. Nick won the race. Which proves the adage. (Message edited by blake on January 27, 2011) | ||
| Therealassmikeg |
Steve, Unfortunately you've made a number of changes at one time, instead of one at a time. Hard to tell you what really is upsetting your feel for the bike. One idea would be to start from scratch and remove everything you've installed except for the tires, and go from there. As this might make sense it may not be the best route yet. Lets think of this differently... What has changed since you last rode the bike "hard" before your upgrade? ...And what would be the most logical drastic change you made that may cause this? First, I'm thinking the answer to this question could be a lower ambient temperature. This will affect the compression and rebound of your suspension, also road temps are colder now and it could be possible that your tire aren't heating as they should. Second, The most drastic change you made that may affect this (imho) would be the tires you put on and the pressures you are running in them. It could be as simple as changing the pressures to get the right feel out of them. Food for thought... |
