| Author | Message | ||
     Dr_greg |
I've known about this trait since my test ride in July 2002 (bought the 9R in August 2002), but last weekend it just about got me killed. Any way to reduce this tendency? I'm running M-1 Sportecs, suspension set for my weight (150 lb) as per the sheet that everyone knows about. Thanks for any help. | ||
| Fullpower |
two wheeled vehicles do that. practice more. | ||
| M1combat |
They certainly do... The Dunlop207's were VERY bad about this unless you're really hanging off like a pro. The metzeler's mostly clear it up but Dean is correct, two wheeled vehicles just do that. It's because the centerline of the bike is above the center of the contact patch. An object is straight line motion and all that... Tire pressure is very important as well. I run my front tire two pounds lower than my rear. 34/36 F/R for me w/ Sportecs. Also, once the front tire gets worn down it'll feel less than optimal... | ||
| Diablobrian |
Xb's are not terribly tolerant of "trail braking" in comparison with bikes with "softer" geometry. The tires you are running should make it better than stock though. Try to do your best to set cornering speed prior to entering corner. Smooth=fast. As always though try to keep it moderate on the street. try to look through the corner to reduce the need for braking while leaned over. Keep steady throttle in the corner. throttle and/or braking inputs unsettle your chassis. | ||
| Dr_greg |
Fullpower, I also own a 2000 Aprilia Mille which doesn't stand up AT ALL even with heavy application of the front brake in corners. It is (in my book) the only negative handling characteristic of the 9R. My '86 VFR750 stood up somewhat, but not as bad as the 9R. It's a pretty well-known characteristic. | ||
| Fullpower |
maybe that sounded trite, apologies offered. the stand-up while braking is more pronounced with wider rear tires, including the stock d207. the Z6 very much reduced this effect on my bike, but it is more pronounced after the rear gets worn flat in the middle. the stand-up IS inherent to a two wheeler, and is, predictably, more noticeable with a steeper steering head angle. if you ride hard and often, you will instinctively counter the effect, and will not notice it. enjoy the ride. dean | ||
| Dr_greg |
Diablo, I basically do all that. "Slow in, fast out", "brake then turn", "back on the gas through the corner", etc. I've done track days. But this time I got really surprised! Glad there was no oncoming traffic. | ||
| Daves |
Glad you are ok. | ||
| Diablobrian |
No problem Dr Greg, I was just trying to help cover some of the most common mistakes I see. No offense intended. | ||
| Rsh |
You can try the (smooth racetrack use) settings as a starting point. The settings were published in the May/June issue of fuell magazine. The settings are very aggressive and offer quick turn in and and the ability to hold a very tight line. I am using these settings currently and I ride all over the place with them. The settings seem to lessen the stand up but I have not had to grab a big hand full of brake while leaned over. Check the knowledge vault. http://www.badweatherbikers.com/buell/messages/3842/107725.html?1124896875 scroll to the bottom you will see the smooth racetrack settings | ||
| M1combat |
Yeah... It seems like if you know what you're doing then it's probably a setup issue. Please don't take offense, but I have a hard time (especially with myself) assuming that a person actually knows what they're doing though  . I'd look at tire pressure first. One thing though... If your arms are too stiff and you apply the brakes... your upper body moving forwards/outwards can put a tad bit more pressure on the outside bar. Of course, this will cause some stand up and it will be more pronounced on a bike with "radical" geometry as the moto rags like to call it. The XB very much rewards "proper form". I use 2lbs less pressure on the front as I mentioned earlier. That said, I do get a tad bit of under steer if I don't get on the gas soon enough coming into a corner (I don't believe that's caused by the pressure though). I'm a ways from the stock setup. She's excellent coming out though . As far as MY tire/setup/technique combination I don't get much stand up at all unless I really need a good deal of brakes mid-corner. I get a little if I use ONLY the front. If I use the rear or both it doesn't stand up at all. I try to avoid doing anything that requires the need for trail-braking on the street though. What are your front/rear pre-loads at? "It's a pretty well-known characteristic." Until you change tires... Then it seems to be a setup or technique issue. The Firebolts seem to be very sensitive to setup changes and as I said, they seem to reward proper technique. The other thing to remember is that the adjustment screws on the stock Firebolt suspension seem to be fairly sensitive as well. Actually, it's probably one or the other. Either way, as a package, the XB is sensitive to setup changes... this includes tire pressure. | ||
| Wo1sjb |
Here's just a little thought that maybe someone a lot smarter than me can clear up. Is it maybe the one perimeter mounted disc and the unequal forces on what is basically a big gyroscope? In the helicopter world we call it gyroscopic precession and associated phase lag. Just a thought, I'm open to being wrong though. | ||
| Dbird29 |
Erik Buell talked at the meeting in Colorado about how the Buell wheel has less precession than others. I think there are some charts somewhere on the Buell.com site. | ||
| M1combat |
That would only be an issue if the mounting points for the rotor were flexible. As it is, you'll notice that the mounts for the rotor are attatched to the center of the rim. Basically... If the wheel doesn't flex at the rim, it's a non-issue. If the wheel DID flex at the rim (it doesn't I'm sure...) then the bike would do some VERY scary things while braking. It doesn't  . The wheel is a rigid system. A helicopter rotor is not . | ||
| Wo1sjb |
Good point, I figured someone had to be smarter than me on this one. I'll just go out and ride my bike some more and stop hurting my brain trying to figure this out.  | ||
| Blake |
Best thing is to practice and become accustomed to how your bike handles. Imagine if you had only ridden your Buell and then switched to a bike like the Aprilia that exhibited little to no tendency to resist turn-in under braking. Same effect, just in the opposite direction. | ||
| Blake |
You might try adjusting your sag front and rear in various ways to see if any adjustments affect the tendency to stand-up under braking. | ||
| Dbird29 |
Tires cured my standing up in the corners. Pirelli Scorpion Syncs. | ||
| Henrik |
Here's a thought; different brand and model tires - even if they're indicated the same size - will have slightly different circumference. This, in effect, will change the geometry of the bike. Sportrider Magazine always measure the stock tires vs. other brand tires they're using in tests and such, and adjust front and rear ride height (when possible) to bring the geometry back to stock. Henrik | ||
| Dana P. |
Henrik I'm running the same tire without that problem.Actually its better then the factory 207's like others have indicated.I think you may be off in your settings someplace. (Message edited by bads1 on September 01, 2005) | ||
| Bruceclay |
I did notice a dramatic reduction in this problem when I set up with the "aggressive" settings. | ||
| Buellerx |
I am also running the Pirelli Scorpion Syncs which were a really big improvement in the bikes handeling and reduced (but not eliminated) the tendancy for it to "stand up" under braking. Just recently I set up the suspention using the "aggressive riding" settings and wow! Another big improvement. It seems like the bike just keeps getting better in the handeling department. When I put in the new settings I went down on front pre-load and up a notch on rear pre-load from where I had started. It totally transformed the way the bike corners. After changing my suspention set up, I was taking some pretty nice S turns on a ramp that leads on to the freeway. I looked down and noticed my exit speed on the last turn was about 100MPH. I thought man I was really moving. The amazing part was I was riding 2 up. It really didnt seem like I was pushing the bike that hard. I just leaned in to it a little and it just went right over and held the line all the way through the turn. I cant believe I had been riding so long on the other settings. | ||
| Morts |
Tires also cured mine, pirelli supercorsa's road compound, the profile is totally different and the handling is incredible. Grip =10 drive out = 10, confidence =10 stability = 10, braking in corner =8 Prior it was about 5 This is not a trite valuation it is considered, I used to race and tires are a constant fascination and a huge performance modification if you choose the right ones!!! | ||
| Surveyor |
I found that dropping the front end ride height improved the turn-in capability under braking but at the cost of front end stability. Ultimately I had to change my conservative riding style to more extreme "hanging off" which is OK on the track once you get used to it....in my experience the problem doesn't arise on the road.....not the way I ride anyway. | ||
| Trojan |
The only way that we found to totally eliminate this problem on our race bike was to replace the OE ZTL brake setup with a pair of Brembo radial mount calipers, twin 320mm discs and Dymag wheel. This made a MASSIVE improvement to the handling and braking potential of the bike. Turn in was quicker and the brakes could be used HARD right up to the apex of a corner without fighting the bike wanting to go straight on. Another problem we had with track use was that the original rotor and pads got so hot that we ran out of brakes in around 3 laps (a set of pads would be destroyed after 3 or 4 short races). We also tried various pad compounds to no avail. This may be a little overkill for road use but it certainly worked   | ||
| M1combat |
There's no way changing the brake configuration alone could have made a difference in the bikes tendency to stand under braking. The wheel does not flex at the rim... If the brake system did have an effect on standing under braking, then it would be more pronounced in one direction. It's not. Can you draw a free body diagram for me to show me exactly how you think the single ZTL rotor causes this tendency? What else changed when you changed the brake setup? How come I haven't heard of any of the FX teams complaining about standing under braking caused by the ZTL setup? A couple of the initially changed to dual rotors but every one of them said that they did this because the caliper couldn't hold up for an entire race. Buell told them to go back to the ZTL and then designed an eight piston caliper for them that seems to do just fine. Maybe you just need one of those neato eight piston calipers? Standing under braking is a function of CG height, rake, trail and tire geometry (more importantly, the relationship of the front profile to the rear profile, not necessarily the profile of one set of tires vs. another set). In any case, I would very much appreciate it if you could find ANYONE who could show me the math. Thanks in advance . | ||
| Trojan |
How come I haven't heard of any of the FX teams complaining about standing under braking caused by the ZTL setup? A couple of the initially changed to dual rotors but every one of them said that they did this because the caliper couldn't hold up for an entire race. Buell told them to go back to the ZTL and then designed an eight piston caliper for them that seems to do just fine. The FX teams have basically been told to use the ZTL brake by the factory. Having spoken to the crew chief from Hals and Rich at Innovative I know that they would prefer to change to a similar setup to the one we used. I have no maths or diagrams to prove it one way or the other, just seat of the pants experience of both systems. We had even raised the rear of the bike by 5mm to make it steer quicker, which should have amplified the problem but it was still much better than stock. | ||
| M1combat |
I agree that the factory told them to go back to the ZTL setup, but why do the FX teams want to go with the dual rotor? Personally, I doubt that it's to try to fix the standing issue. I know it's mostly a different scenario, but I've found with my bike that it still tries to stand a bit under braking if I only use the front brake. If I use both or just the rear when leaned over it doesn't happen. | ||
| Dana P. |
Trojan you are correct that the factory had them use the brakes but Hal's continues to use the ZTL brake and they are no longer factory backed.Rich (INNOVATIVE) has said and so has Terry (HAL'S) have said that they are going through rotors like candy but not because of the brakes making the bike standup under braking.ZTL's just weren't lasting.And not quite as powerful for the intentions. | ||
| Jeremyh |
you could just do yourself the favor of planning to slow down a little bit more before entering the turn. i loved the strength and response of the ZTL setup but found it to be less predictable than the dual rotors i now have. |
