racer
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Posts posted by racer
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Wow. I thought I was just being disingenuously self-deprecating when I said I wasn't up on current tire technology....lol.
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Here is the basic thing with trail braking, and the area it can be problematic: as the smaller of the 2 tires, and the smaller contact patch, maximum traction cannot be achieved, until the bike is stabilized, correct weight for the contact patch. The normal solution to a front tire pushing (sliding) is to get the gas back on, as there is too much weight on the front.
Does that make sense?
CF
Yep. Bigger contact patch at the rear equals more available traction at the rear, equals more speed when the weight is properly balanced front to back.
No matter how big you make the contact patch at the front, the rear will always be bigger.
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Right! More guys loose the front by making mistakes (not on the gas, tight on the bars). How about how many guys do you see crashing on the brakes on the way in? Rarely one can loose the front from too little weight. Can happen, but don't it's that common.
How many guys do I see crashing on the brakes on the way in?
Like relative to the frequency of crashes on the gas, ie highside?
From my own memory corner working, far more crashes on the brakes than on the gas.
Your not seeing these crashes because someone isnt employing trailbraking properly, unless you area corner worker for AMA or motoGP. It is because the less skilled rider will freak out and over brake therefore causing their tire to washout so your point doesnt add anything to a discussion on trailbraking and where and when to use it for experienced racers.
I am an AMA National cornerworker. In fact, I am an AMA National rider.
Trailbraking does allow for faster around the track period. By placing more Gs on the front tire you are adding grip and also contact patch. Like Collin Edwards says the front tire actually spreads under load and provides more contact patch and in turn greater grip and in turn greater corner speed. Like Stuman says this thread isnt addressing the question of whether trailbraking is faster, as that question is already answered for us in every top level race. This is addressing where and when to employ the technique. There doesnt seem to be an easy formula for this as there are sooo many variables to consider, however I think it is a very intersting discussion and one that a very experienced smart racer could add much insight to.That is not quite what Stuman said. Here is what he said:
Again this thread is about where and when to trail brake, not whether or not trail braking is an effective technique. This thread is all about whether one should trail brake or not, whether or not to do it in every corner or just some corners and if only some then which ones and why I think is really the point we are discussing.The critical difference is that he suggests that trailbraking can be an effective technique. He does not make a blanket statement that it is "faster". In any case, trained school instructors and smart pro level racers (like Stuman) have explained how and when trailbraking can be effective here in this thread.
Racer you made this statment"The effect of "adding traction" (to gain speed) with trailbraking decreases proportionally with lean angle until the bike reaches 45° of lean angle. After that, more brake equals less traction, period. (No matter how fast you are going or how good you are.)"
Where in the world did you come up with this? It doesn't decrease proportionally, for reasons I explained above. If it did there would be no need to trail brake because you wouldnt gain anything. How in the hell did you come up with 45 degree angle as a point where more brakes equal less t reaction?
Below 45 degrees of lean angle, the component of horizontal loading due to braking will "outweigh" the component of vertical loading due to braking.
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The factory recommendation is like 36 front, 42 rear. What I run is more like 32-33 front, 38 or so rear. (not very precise with it) I've got a dial gauge, not one of the little spring-pen POS gauges.
Is GP Suspension anywhere remotely near the east coast? I'm in Baltimore, MD, so if it's a shop in California, there's no way I'm gonna get my bike all the way down there.
I've been meaning to set the sag...it's just a matter of finding the time and working up the guts to tinker with it. That and it's hard to find someone to hold the bike up while I measure. The forks I can do with a zip-tie like Racer suggested, but the rear shock I need to think of something a little more creative.
36 F / 42 R ?
I am not familiar with newer tires since 2004 but that sounds pretty hard. Can you be more specific? Is it perhaps max pressure for a certain load?
http://www.google.com/search?hl=en&q=m...amp;btnG=Search
http://www.google.com/search?hl=en&q=m...G=Google+Search
A well-trained bike mechanic should be able to swap the springs and get it set up ok. I noted a post for you in another thread about a spring manufacturer and prices. If you really can't find anyone to hold the yard stick, send me a PM and you can ride up to Pittsburgh and I will help you. I'm not a suspension guru but I'm closer than Cali....lol.
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Right! More guys loose the front by making mistakes (not on the gas, tight on the bars). How about how many guys do you see crashing on the brakes on the way in? Rarely one can loose the front from too little weight. Can happen, but don't it's that common.
How many guys do I see crashing on the brakes on the way in?
Like relative to the frequency of crashes on the gas, ie highside?
From my own memory corner working, far more crashes on the brakes than on the gas.
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Racer---a question to you:
What causes the front end to push on a motorcycle? (most of the time). Too much, or too little weight on it? What fixes the majority of those problems?
Cobie
Oh sure...there you go keeping it simple again.
Answers:
Too much weight.
Acceleration.
(Sheepish grin)
I do seem to enjoy chasing my own tail around convoluted circles sometimes. Especially before I have a second cup of coffee in the morning...lol. I'm really not purposely trying to confuse people. More like letting my mind wander out loud. Bad habit.
To my own mind, I have never trail braked to put more weight on the front wheel, but, for a moment, from a certain point of view, it seemed like it might make sense above a certain lean angle. Like getting above the wheel to create more traction with a dirt bike on a soft surface?
However, after thinking about it, I can't think of a situation at the sustained mild lean angles (where that technique might be effective on a road bike) that would require more down force to create more traction. If you are vertical enough to add more vertical weight component than lateral component by trail braking, you generally aren't going fast enough to overcome the available traction anyway (unless maybe it is very slippery or wet conditions) in which case more weight is the last thing you need!
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Hi Thor,
Thank you for your opinion regarding the steering issue.
Thanks,
racer
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You need a zip tie (or what may officially be called a "wire tie" by some folks) to put on the front fork tube. I'm sure you can get cheap ones at the hardware store, building/electrical supply or home depot type store. You wrap one around your fork tube and you don't need anyone to do anything. The zip tie moves when you sit on the bike and the fork compresses. Then you measure the distance to where the fork goes back to when you get off the bike. To be perfectly perfect, you want to be in your proper riding position with your feet off the ground, but even sitting on the bike and picking your feet up for a moment or two should get you close.
You only need to zip tie one fork tube, and then look at the adjusters and count the lines to make sure they are even on both forks. And you only need to think about geometry front to back, not side to side. In any case, considering where you are now, you will only make it better.
I hate to give you a specific number without being there, but, from what you have said, I'd think you could put a half an inch on the forks and shock and still have plenty of way to go while still getting enough of a difference to really help for a start. I would not put it off or ignore it. It really is important. And don't worry about adjusting things that are meant to be adjusted. That's what they are there for. Worst case scenario, you re-adjust it. When I rode on the street, I used to adjust my damping rates every other day depending on what kind of riding I was going to be doing.
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It has been a long time since I took Level I, is there something I can read to refresh my memory?
Right here: https://secure.echoalley.com/superbikeschool/store/
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One other thing. Have you checked your tire pressure lately? Sometimes the obvious can be overlooked. Like why the bike wont start...then someone flips the kill switch
LOL ... I hate when I do that.
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Hey Squirrels,
If you are still around, check out the 06 636 thread in "set up and handling". EA6BMECH posted some really good info for you there.
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Thanks for bumping this thread EA6BMECH.
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I'm still thinking it through, but, there may be more than a simple difference of perspective between trailbraking to "increase traction", so to speak....and simply spreading the braking out over a longer distance or compressing it into a later timeframe which is probably what most people are really doing (or perhaps think they are doing).
In other words, the level of riding at which trailbraking would become a tool to increase traction (over the amount of traction that would be available without trailbraking) to artificially create "virtual" percentage points of speed by "unnaturally" increasing the vertical component of stress on the compound would be, in my opinion, an extremely advanced level.
In other words, by definition, at that point...a rider is carrying too much speed at the turn in point to make the corner without trailbraking to increase traction to carry that extra speed, while simultaneously slowing enough to make the turn when they do let off the brake. In other words, the rider would wash the front if they didn't trailbrake.
Honestly, I've never approached it or thought about it from this angle before and I still do not feel quite clear about this aspect. Only that, in my opinion, that would be a level of skill that only the fastest and most gifted top level riders would be consciously or intentionally working with.
Or perhaps, it is merely a turned around way or reflection of the way I have always considered it (or just did it) until now.
Hmmm...
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Good points KOCook,
I'd like to add a point or two that may provide some hard data points from which to explore those limits.
The effect of "adding traction" (to gain speed) with trailbraking decreases proportionally with lean angle until the bike reaches 45° of lean angle. After that, more brake equals less traction, period. (No matter how fast you are going or how good you are.) Prior to that point, there will be a load line or characterisitc curve and crossover point of diminishing returns that will dictate a constantly decreasing amount of brake as the bike is leaned over. In other words, due to the lateral cornering forces, the effectiveness of more brake for more traction significantly decreases the moment the bike leaves 90° straight up and down until it reaches absolute zero at 45°.
So if 'x' amount of braking is the limit to add traction at 85°, then at 60°, that same pressure will be reducing traction, not adding it. More lean equals less brake. Period. I'd like to reiterate that the amount of brake being used in this circumstance is very small. Being off the gas combined with the addition of lean angle and the angular acceleration of traveling forward in a circle will do the vast majority of loading the front tire for usable traction in any situation. Using trailbraking to increase traction for more speed will only apply in certain types of corners on certain types of racetracks. It will not serve a rider in the type of corner where the bike needs to be "flicked" in quickly to max lean angle, ie. like most corners on most racetracks in the United States.
On the street, trailbraking serves no practical purpose outside of a decreasing radius turn or an emergency situation where a rider has overcooked a turn entry and is trying to scrub off enough speed to be able to get it turned in before the shoulder of the road. In any case, a street rider attempting to find the last 2 mph of speed through a decreasing radius corner by using trailbraking is a statistic waiting to happen. Explorations of the ragged edge or the limits of traction and how far they can be pushed belong in the controlled environment of a closed course racetrack for everyone's safety. Preferrably that exploration should begin with a CSS course where a trained professional instructor can offer you personalized attention and training that is custom tailored for your specific needs on the day. Yes, that is a shameless plug, and the minute I stop owing my life to the school, I'll stop offering it.
Cheers,
BH
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Who told you you need to spend 2-3 grand to make it work for you?
If they are trying to sell you an Ohlins fork or shock, I suppose you could spend something in that range...if you were contesting the national championship and had a suspension tuner on the payroll ....
Seriously, upgrading your springs shouldn't be more than a few hundred or so at most in my opinion.
As for your question regarding "just how far is too far?" to go trying to work around what you have...
I don't know if there is a firm specification on how far you can go before you reach a point of diminishing returns or where the travel will become too short to be effective, but, what I would do first is start by measuring your sag where it is now and see how far off you are.
I think it makes sense to get a good idea of where you are now before trying to go somewhere else.
If it is set for someone of 170 lbs now and the range for optimum performance is something like 125-225 lbs you are probably somewhere in the middle of the range right now and surely have some room to work with to improve your situation.
I recommend measuring your sag now to have a very clear idea of what you are looking at.
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Oh, I haven't priced srpings lately.
The last time I bought aftermarket racing srpings for my old FZR from Progressive they were fairly inexpensive...like $50 dollars. That was probably fifteen years ago. Try googling progressive for a start. but remember, you need a srping for the street that is properly rated...not a race spring. Although, if you can't find the OEM equivalant option two spring, you may end up getting whatever works.
There are several good suspension gurus around. What part of the country are you in. Or are you in the USA??? doh
The other option is to go to the dealership or one of the mail order discount places that carry OEM stuff. A good parts guy can see if there is an optional OEM spring available but it will almost certainly be more expensive than aftermarket.
Actually, I dont' know about that anymore. Some for the discount OEM places are really high dicount..you'll need to make some calls and research.
Some other riders/racers here might be able to suggest current aftermarket spring sources.
If you have basic mechanical aptitude, I think you can swap fork springs yourself.
But you'll probably need a press to release the spring keepers on the rear shock and install the new spring though.
In any case, it really shouldn't cost more than a couple of hundred for new springs without install labor. I could be wrong though. If you pay someone to do the labor, I think that will be a couple of hours on the book at most. Again, call a shop and ask. I don't work in the industry anymore, I hav no idea what rates are these days
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Thanks for the heads-up. THere are a lot of posts drifting around about setting sag. I've heard, though, that compression damping should be increased as well whenever preload is added to help keep the suspension from bottoming out. Any truth to that? Or should I just leave the compression damping as-is?
Also...can just the springs in the forks and the rear be replaced without spending thousands of dollars on aftermarket suspension parts?
I was going to leave the damping discussion until after the sag discussion because it is a whole nother ball game.
The basic function of the spring is to support the bike and you and absorb bumps by going bouncy bouncy bouncy.
The basic function of damping is to limit the the bouncy bouncy bouncy to just one bouncy and control the rate of the bouncy to prevent the wheel from traveling further than it needs to on the way up and to come back down fast enough to keep the wheel in constant contact with the pavement.
For the soft spring, I think you will need more compression damping, and but probably less rebound damping.
For the harder spring I think you will probably want less compression damping and more rebound damping.
Does that make sense?
Assuming a good shock with good oil and such, chances are the stock settings will be a good starting point from which to experiment.
Once you have the spring in the ballpark, you should take each damping control in order, say start with rebound and whack all the way in and go for a ride. Then whack it all the way out and go for another ride to get a very clear idea of how each extreme feels to start to get an idea of how to feel the diference betwen minor adjustments and what they mean.
Then do the same for compression.
But do only one at a time. I repeat...adjust one thing at a time. Do either compresion and only compression at either extreme, then do rebound.
If you start doing them together you will chase your tail around and never get a solid idea of what to feel for. Again make large adjustments to get a real idea and feel for what it does.
Actually, you know what...scratch that. For just getting a feel for what damping is about, you can whack everything to zero and then everything to ten to get a good idea for damping and no damping. And then start to break it up.
When making adjustments for finer tuning, making one adjustment at a time becomes critical. And you still want to go a bit more than you think you might need to at first to get a good feedback until you develop a finer sense for it to be able to really feel what one click does to your rear compression damping going into a hundred mile an hour sweeper.
My nickel.
Actually, you can do that now, before sag. But you really need to get the sag done. That is the basis and foundation for proper suspension adjustment
BH
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The reason I haven't monkeyed with the stock suspension settings is because 1) I have no idea what I'm doing, and 2), more importantly, from what I've read, the stock SPRINGS don't have the correct spring rate to support a rider of my weight. I posted a thread a little while back in the set-up forum about it...you responded. But I don't currently have the money to replace the stock springs. From what I've heard, the most I can do is crank up the preload, but that would take the travel out of the suspension, essentially eliminating its function.
I'm worried about having to dial in so much preload that the suspension will end up bottoming/topping way too easily...but I cant' afford a new suspension.
That, the incorrect spring rate, is a valid issue and concern. As is the possibility that you will lose a good deal of range of movement and degrade the progressive nature of the spring response as well in the process of cranking down and compressing the spring too short and tight beyond its operational range.
However, at the end of the day, it is just as possible to bottom out a suspension that is too soft...eh?
I agree that for spirited riding, the ultimate solution will be new springs. At 250 lbs plus gear I'm pretty sure you're going to be 20-30 lbs over the maximum rating of a typical stock shock spring range ...when new. So, I agree that really should be addressed.
However, keep in mind that the manufacturer intends for a street bike to be able to operate safely with a passenger. It isn't like you are racing and need the last half a percent of performance for the ulitmate lap here. It might not be perfection, but, I have to believe that you will only increase safety and handling characteristic by at least approaching a happy medium.
In my opinion, adding some pre-load to approach a happy medium with what you have HAS to be better than how it is must be set now (set for someone 80-90 lbs lighter than you).
I am not familiar with your specific year/model, however, generally, there is a lock ring and an adjustment ring atop the shock spring which ideally you use a "spanner" style shock wrench to adjust. Often times a "spanner" style or "hook" type shock wrench should be supplied in your under seat emergency tool kit. It might be an attachment for a 3/8" ratchet or it could be something you assemble with the kit handle, but, in a pinch, a screwdriver and a claw hammer will work fine to tap the ring around, albeit carefully to not scratch the shock body or skin your knuckles...lol.
Again, I think most all modern sport bikes come with threaded adjusters for the front fork pre-load that will be located on top of the fork cap above the triple tree and adjusted with a crescent wrench or large socket depending on the tools at hand.
In a nutshell, you can wrap a zip tie around the fork leg, sit on the bike and measure how far the zip tie moves down the fork for your front sag. Some people say to "top out" the fork by pulling up on the hande bar to set the pre sag measurement (a famous team suzuki tuner told me that) some people just bounce the bike to find a static sag start point before you sit on the bike to move the zip tie.
For you, for now, in this case, I wouldn't get too too concerned about which way is better or proper. I think you simply need to get something closer in the ball park because I have to guess that you might have something like two inches of sag going on. Ideally, for the street, something between 1 and 1.25 inches is a general rule of thumb recommended front and rear. For you, in my opinion, even getting toward one and a half (1.5) inches should help. Of course, I don't know, perhaps you have 1.5 now or 3 inches now....I can't really say. But anything has to better than where you are now IMO.
I use a yard stick stood on end next to some fixed point on the rear subframe at a point located vertically above the axle. It helps to have a second person read the stick for that one or even use a pencil to mark it.
I don't have time to go searching right now , but, I think Keith himself did a posting here about the best method for all of this.
Gotta run. Lemme know how you go.
BH
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LOL
Yes, your experince is not so unusual.
My first inclination being that you began to notice after you switched tires is that it had something to do with tire swap and a more aggressive or fresher profile on the rear encouraging you to lean further than you had been and the new angle being beyond where you were going and the front being a bit squared off, or perhaps it is a matter of a more aggressive profile in the rear simply not matching. You should be able to eyeball that by getting down low and looking at the front tire from in front of it and at the rear tire from behind it to compare profiles and you might also be able compare the unused stripes for a clue.
AS a rule, I always replace tires in matched sets, especially for a sport bike.
However, from what you say, it sounds like you acknowledge your suspension being set WAY too soft for you? You said you are riding the stock suspension "settings". Does that mean just stock suspension or that you have not adjusted the preload and sag on that stock shock/fork?
If it is the stock settings for 170 lbs and you are over 250 with gear...I wouldn 't even guess what is going on until you properly adjust what you have. That by itself should give you a whole new picture. I cannot emphasize how non-trivial adjusting your sag is, especially considering how far out of range you apparently are.
There are several threads here devoted to the proper sag and how to set it including Keith Code's you can find with the search function. If you need help, let me know and I will talk you through it.
Cheers,
BH
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Yes, CSS will change your riding to a degree that you notice.
If you haven't already done so, I would suggest familiarizing yourself with "A Twist of the Wrist" before you do your Level 1 school. In my opinion, you will be that much better prepared to absorb and benefit from the experience.
And, although it seems to be the most obvious or straightforward concrete datum a rider can see, how far you get leaned over or how you compare to another rider is not the best measure of your riding skill or confidence. There are many reasons a street bike riding on the street cannot use every last millimeter of tire or lean angle and more important or meaningful ways to gauge your own progress than comparing yourself to another rider.
The best riders and racers work their own program and the podium is a measure of how well they work their own program.
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Niiiiiice!!!
Thanks for sharing that!
Great soundtrack, too!
Looking forward to Brno!
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Dragged the brake lever in a left turn, eh? That's pretty amazing!
I mean I've come close to dragging an elbow once or twice, but a brake lever ... all I can say is 'wow'.
Hat's off to ya, mate!
What track was that at?
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I did a major rewrite and edit on the long post above. I also read back through your original post, blarson, to refresh my memory of what all you said in your long post...lol.
Something that didn't occur to me because it seems obvious (to me) but might not be so for everyone would be to inspect the rear axle and nut to make absolutely certain they are really tight and that the axle is not sliding around under cornering forces.
The rear axle nut tends to be the highest torqued on any motorcycle. And even though it may seem snug with the old crescent wrench, it generally takes about 50-70 ft lbs of torque to secure properly. That is like 70 lbs of force applied to the end of a foot long wrench. A "close enough" measure might be to carefully use your foot or lean on a closed end wrench (like the closed end axle wrench with handle extension that is usually supplied in the under seat emergency tool kit) with your hand until you grunt if you don't have a proper torque wrench and socket kit. (I cannot overstate the value of that kit. If yours is missing, you'll want to order a new (or used) one and/or even create your own emergency tool kit.)
You could use a socket on a medium/large ratchet handle in a pinch if you have nothing else, but; that kind of torque can damage the ratchet so it is best to use a fixed wrench or "breaker bar" if you don't have a proper torque wrench.
Also make sure the rear wheel is as close to perfectly in line with the front wheel as possible. The chain adjuster hash marks aren't usually very accurate.
Ok, sorry if I am insulting anyone's intelligence, but, when I bought my first street bike at 19 years old, I certainly did not know this stuff and learned much of it the hard way.
Trail Braking---not That Fastest Way, But They All Do It
in Cornering and Techniques
Posted
Wow. I can sure relate to the endless edits to get something out of my head right. I keep telling myself to use a word processor and wait until I have it right before posting...but for some reason that never seems to happen...lol. Probably because I always start off thinking I can get it all out in the five minutes I have to spare....not.
On that note....I don't have time to go through your post point by point right now, but, I will offer a couple of thoughts.
First is that you are correct about the banking offering more friction. The reason is because it effectively reduces the lean angle between the bike and the pavement allowing more force to be applied since there will be more vertical component at less lean angle.
I know you think that applying more down force to the front tire will create more friction, and it will. But, there is only so much down force you can apply at lean and even though you may be able to create more positive G's at speed under braking than negative G's under acceleration, like I said before, you can only apply any degree of down force above 45 degrees. Below 45 degrees, it goes sideways.
So no matter how much down force you put on the front tire, it will always be limited by lean angle and the traction will always be greater at the rear because there is more friction available from a larger contact patch.
Also, there is a whole nother component we haven't discussed yet. Up to now, we have only been considering the traction wrt lateral vs vertical.
You have to consider the positive and negative wheel torque from acceleration and braking leading to rear wheel spin or impending front lock up. You cannot ignore this component or fail to consider it in your trailbraking analysis.
Gotta run.
racer
PS I'm not sure what you mean by centripetal acceleration. Do you mean angular acceleration perhaps?
"lessing" = decreasing or reducing?
It sounds to me like you might enjoy this website: http://www.glenbrook.k12.il.us/gbssci/phys/Class/BBoard.html