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noamkrief

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noamkrief last won the day on March 29

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About noamkrief

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    Cornering Artist
  • Birthday 02/09/1982

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  1. Anyone watch motoGP? Sometimes they have onboard video with lean/throttle/brake overlay. I watch those very carefully, never once seen an overlap between braking and throttle. Not even when Rossi rides (because there are rumors he applies this technique of brakes and gas at the same time) I have data from Xavi Vierge and he doesn't do it either. In theory I could understand the concept but the "juice is not worth the squeeze". It's too distracting, and it could take away from your sensitivity on the brake lever if you are also trying to apply 5% throttle. If you are not at the limit, and not going fast, you don't need sensitivity on the brake lever because you won't be using it anyway at high lean angles right? So when you get faster, you will find yourself with some light brakes at 48 deg lean, and if you press just a tiny bit more on the lever, your front end will close.
  2. It's a combination of camber thrust and steering angle. At a 45 degree lean angle, the profile of the tire generates alot of camber thrust, like when you roll a cone on the ground, it rolls in circles. Camber thrust at 45 degrees makes the bike want to turn at a radius of about 5 - 10 feet depending on your specific tire profile. This radius is much less of a radius we negotiate at the track. This is why we can have situations where the front wheel is actually pointing towards the outside of the turn during cornering rather than the inside. That is because camber thrust is TOO large. without a rider on a bike, if it leans to 45 degrees at 100 meter radius is 112km/h If you add a rider and rider is sitting on bike in the center same condition. 45 deg, 100m 112km/h If rider is hanging off, 2 things can happen: 1) bike is leaning 43 degrees 100 meter radius 112km/h (contact patch to center of gravity angle is now 45 deg) 2) bike is still leaning 45 deg 100 meter radius ~120km/h (contact patch to center of gravity angle is now 47 deg) Hanging off the bike reduces bike lean angle, so suspension works more efficiently and you gain more mechanical grip regardless of the coefficient of friction of your tire. If you hang off the bike alot, you reduce the effect of camber thrust, and your front tire will have to turn more into the corner. If you are a beginner rider, you do not need to hang off the bike because you don't need the extra 1% suspension effectiveness. A bike doesn't fall because the steering rack can turn. It's not the rotating mass of the wheels. If you weld your steering column so the front wheel cannot turn, your bike will fall.
  3. Faffi, yes quick steering gives you more possibility of lines. Especially the line that makes the biggest radius around a bend, like that of a moto3 bike. Yes - we can have a rider creating an un-necessarily tight radius around a specific turn leaning at 55 degrees going slower than another rider who chose a line which provides them a larger radius, leaning at 45 degrees, and this 2nd rider would be going faster. That being said, if a bike/tire is capable of reaching 55 degrees, a lean angle of 55 should 100% be achieved at some portion of any particular turn. This portion would be the moment where you are not braking, and not accelerating. This portion can last 0.1 seconds, or 4 seconds depending on the particular characteristic of that corner. You will almost NEVER want to reach a lean angle of 45 degrees maximum at a turn, where your bike is capable of 55 degrees. It just means you could have gone faster. I'll make an video on this topic in the near future.
  4. Hey Faffi. The article from cycleworld pretty much explained what is happening and this phenomenon of why moto3 corner faster than motogp so I suggest you read it very carefully. The MotoGP video is leaving out some important details in order to glorify and promote moto3 in with this concept of "hey, moto3 still has its strong points, they corner faster". Sort of like - rooting for the underdog. The reality is that moto3 bikes do not do anything better than motogp bikes besides maybe the flick rates (from side to side). They certainly are NOT capable of cornering at a higher speed than motogp bikes and the article from cycleworld alluded to that fact. I'll try to explain again. Imagine a motorcycle doing circles in a parking lot. Constant radius circles non stop at a constant speed. The higher the lean angle, the faster these circles can be negotiated regardless of the weight of the bike. At a certain lean angle, a given motorcycle tires would start to slide. This is dependent on the coefficient of friction of the tires. If the tire coefficient of friction is 1, anything past 45 degrees would result in a slide, and if not corrected, a fall. If the tire coefficient of friction is 2, anything past 63.4 degrees would result in a slide, and if not corrected, a fall. We know that motogp tires have a higher coefficient of friction compared to the japanese made KR133 dunlops used by moto3. So moto3 bikes can not lean as far as motogp bikes. The article explained this by how moto3 riders do not drag their elbows, but motogp do this frequently, and even tuck in their elbows a bit to allow even MORE lean angle. I will try to get moto3 data for Valencia and compare it to moto2 data to compare max lean angles and see which achieve higher. I know moto2 usually do around 56-58 degrees. Motogp can get to 60-63. So why do moto3 bikes have a FASTER mid corner speed than Moto2 or MotoGP? The article also explained this. It's because moto3 bikes do not have high acceleration potential, so their biggest "tool" for speed is momentum and mid corner. Any 1mph they overslow in mid-corner, is a 1mph they will very much struggle to get back. So moto3 riders choose to put emphasis on the corrector strengths of their machines by choosing lines that have the absolute highest radius. MotoGP riders will purposefully create a tighter radius in the entry part of the corner, in order to greatly increase the radius on the exit portion, so they may unleash their 260hp. If a MotoGP bike used the exact same line as a moto3 bike, it would not be competitive compared to other MotoGP bikes as it would not be able to get on the gas early and hard. But its mid corner speed would be greater than that of the moto3 bikes because it is able to achieve higher lean angles due to its greater tire coefficient of friction. Please remember, for constant radius, the only thing that can increase speed is lean. Maximum lean is maximum lateral G's the tire is capable of. Weight of the machine, has nothing to do with it. So what to do? Get stickier tires and you can lean more and you can have more speed at the max lean portion of every corner. Hope this helped clarify.
  5. Ok I see what the confusion is don’t worry. A light bike moto3 with skinny tires will lean to 40 degrees bike lean and because the rider is hanging off to the inside a lot, the effective lean angle - contact patch to CG is 45 degrees. So now this bike is cornering at exactly 1G. Good so far? We agree. Now a heavier bike moto2 rider is hanging off the same distance. But because the moto2 bike weighs more, to achieve an effective lean of 45 degrees (patch to CG) the bike must lean to 43 deg. Now this bike also corners at 1G exactly. So what is the difference in speed around a bend between the two situations? None. Both bikes are at 1G and will make the same mph for a given radius. So why do small bikes have more corner speed? Or do they? I have heard this mentioned before, but the science does not agree. So maybe it’s bogus info - we have to keep an open mind. The main thing that matters is coefficient of friction of the tire. We know MotoGP tires have more grip than moto2 and moto3. So actually MotoGP tire may be able to get to 1.9 lateral gs (I think around 60 deg) and a moto3 maybe only 55deg lean. Important to understand, bike lean angle doesn’t really matter for corner speed. Only contact patch to CG. i know this is super confusing but once you get this concept it is like a light bulb in your head i will say, that if bike lean is more vertical the suspension will work better so you will generate more mechanical grip. But it’s very small differences especially on a smooth track.
  6. Mph has nothing to do with it. I know it’s counter intuitive but i will explain. If your tire coefficient of friction is 1, your tire can only maintain 1G force. Mid corner where you don’t accelerate or decelerate (can be very short amount of time in this zone) your tire will only be subjected to lateral G forces. At 1.01 G your tires begin to slide. (Let’s not discuss slip angles for now) so your tires can only do 1G so your max lean is 45 degrees. At 45.1 you start to slide ok? we also must make a destination between bike lean angle and the lean angle between contact patch and CG - lets call them bike lean and effective lean When we do calculations such as 1G = 45 deg we always mean effective lean angle. Bike lean angle doesn’t matter (except for suspension effectiveness and tire longevity) so a 200 pound bike leaning at 45 degrees in at 300 foot radius would do the exact same speed as a 900 pound bike at 45 degree at 300 radius. moto3 bikes have skinnier tires so their effective lean is close to that of the bike lean . bike lean is always more than effective lean . At 45 degree effective lean you will always generate 1G lateral regardless of speed. Simply does NOT matter. i know it is counter intuitive but it is math and physics. i hope this reply is not frustrating to anyone. noam
  7. Moto2 riders achieve around 57-58 degrees (1.65 lateral G's) at the neutral throttle phase of the corner (0-10% throttle, no brakes) I texted one of the engineers at Kalex and asked him "How do they do 57 degrees? My tires start to slide at around 53 degrees" His reply: "It's Magic :)" Tire coefficient of friction (directly also dependent on track surface) is obviously the biggest variable assuming you don't drag any bike parts before hand. Tires used in Moto2 very similar to the now french made Dunlops KR108 rear KR106 front. (moto2 tires can be obtained from the dunlop dealer in Barcelona) As the OP said - Q4 can do 62 deg lean angle. I don't see how that is possible because my logic says that Moto2 tires must have more grip, so why would moto2 riders stop at 58 degrees? If they could lean more, believe me, they would. They don't have a psychological complex with fear of lean - they lean until the tires start to slide.
  8. Hey guys. I wanted to share some videos I made of me analyzing data of of my lap vs WSBK rider who is also riding my bike around Chuckwalla CW direction. So far I have made 3 videos that are very basic, but a good place to start because they are simple and hopefully easy to understand. My qualifications: I used to race cars, and we were very heavy into data analysis. I also spent many hours with crew-chief of Tech3 and Data Engineer for Gresini which we covered in detail all aspects of data acquisition for motorcycles. Software and data acquisition system: "2D Data Recording" (used on all moto3, moto2 and many MotoGP machines) The videos should be watched in order because they sort of "build" on top of each-other. Video #1 (time spent at lean) https://youtu.be/aJ_E-sUxJc8 Video #2 (roll speeds) https://youtu.be/aUDGNg2WDDM Video #3 (how it is possible that my roll speed is lower and my lean angle is higher) https://youtu.be/02q4I4xnyLc Future videos will all compare WSBK rider lap with my own (order not yet decided): - Roll Rates. How fast do we add or decrease lean angle. I will also cover counter steering, and how it works - Changing Radius during cornering. Entry, neutral, exit type corners and V-type - Motorcycle dynamics (will be many separate videos). Lean angles converted to G's. How to calculate lean angle from radius and speed and the other way around. What are G forces. Braking G's, acceleration G's, combined G's (traction circle). Why a bike does not fall and a self correcting system (rake, trail, offset). Anti-squat. Tire coefficient of friction. Camber thrust. - Focus on entry phase of corners - Focus on mid corner phase - Focus on exit phase - Suspension setup by suspension speed histogram to adjust rebound, compression scientifically. - How to find more time at a given track without a reference lap. - Oversteer & understeer - Sprocket sizes and gear simulations on the software. - Throttle acceptance - Xavi Vierge data analysis from Valencia Qualifying 2016. This will be fun. He brakes at 0.9 G's at 50 degrees lean! Woohoo! - Contact patch. Does a bigger contact patch actually provides more grip? (this one will really piss some people off) - Ideal Tire working temperatures, how we can find them, and how we achieve them. - Yaw
  9. Rear brake should not be used on the racetrack. PERIOD. (unless it rains but i'm not sure exactly). "Backing it in" can be induced by locking up the rear, true. You can use rear brake, or drop the clutch abruptly on downshift. But this is not what you are seeing in MotoGP or moto2. To prove it, go watch a few moto2 races and you can see that even on right hand turns, they back it in and don't use rear brake. It's obvious because now that almost all riders let their inside leg hang during braking, you can see the rear end of the bike "come around" while their right leg is dangling in the air. "Backing it in" is a result of "threshold braking" combined with "trail braking". If you and your bike weigh 500lbs, lets say when you sit on the bike on a constant speed there is 250lb on the front and 250lb on the rear. During very hard braking, you would want 490lb on the front and 10lb on the rear. Just enough weight on the rear so it still sort of "follows" the front. At times, you will see the rear tire skipping. So once the rider start to turn the bike, the front end is gripping and turns, while the rear with 10lb of weight on it continues straight ahead. There you go - you are crossed up... Don't release the brakes enough, and you'll get more and more crossed up until you crash. To sum it up, backing it in is not a stunt that is induced by rear brake like on your BMX bike, it's a result of going very fast into a corner with extremely aggressive trail braking technique. Hope this helps.
  10. Thanks for your reply. You made very good points. Yes - on another post I could not use the term "threshold braking" since no one would know what it means, so I said - 100% brakes and half the people thought I meant braking as hard as my hand can squiz. Also terms like flick the bikes vs turn the bike. One of my instructors hates the word "flick" and when he was critiquing my riding he said "you need to turn faster". So I naturally though - "wow, I'm already almost dragging my elbow, if I go any faster in the turn, I might lowside". but what he meant was to FLICK faster. So basically 1/2 the day we were not talking about the same thing. What a waste. Anyway - it's ok. It's just the way it is. I totally get it. most people just want to ride and go as fast as they can without getting scientific about everything. That's fine
  11. Hi everyone A bit of background, I come from the car racing world and I started riding motorcycles for the 1st time 9 months ago. I learned how to ride from step 1 (didn't even know which lever the clutch was) and within my 1st week of riding, I rode on the highway on the shoulder at 40mph to my first track day. Since then I've done over 60 track days and enjoy bikes much more than cars because the "limit" is alot more dangerous therefore requires alot more skill and finesse. That being said I find alot of flaws in the motorcycle world. I hope I do not offend anyone. I find the motorcycle racing/track world to be a much more "shoot from the hip" type of sport. 1) Data acquisition. Rarely I see anyone using it. How can you tell if the line you are taking is indeed fastest? What feels fast may not necessarily BE fast. 2) Ever heard of a torque wrench? I had the tire guy at the track change my tires and 45 minutes later I asked him what he torqued my axles to. He said "I don't have a torque wrench are you kidding me? This is a sport of FAITH son!" I've ran into this multiple times. 3) Terminology. This is perhaps the most frustrating thing for me. Motorcycle racers and even suspension tuners don't have a unified terminology and when they do agree on something it's a very unscientific word like "backing it it". Sorry - but that's retarded. Here are some terms and definitions and maybe some of you can shed some light on if these terms are recognized here or what the motorcycle equivalent is. Oversteer = the rear end looses traction, the front is still gripping. (overtseer is broken down to the following 2 categories) 1) power oversteer [you guys say: sliding the rear end] = rear looses traction due to excess in power 2) corner entry oversteer [you guys say: backing it in] = rear end looses traction under trail braking phase due to the initial turning force accompanied by the rear end being light due to weight transfer to the front 3) understeer [you guys say: loosing the front] = occurs when the front tire is overtasked between cornering forces and braking and starts to slide. 4) Threshold braking [you guys say: I brake really hard!] = maximum braking that is capable given the conditions and tires. Braking any harder is NOT possible. This should be the goal for most corners 5) Corner exit speed [getting the drive] = get the maximum exit speed possible. The "getting the drive" term seems to make good sense in this case I'm very willing to adapt to the sport and use the terminology that everyone agrees on in the motorcycle world, it's just that I haven't seen consistency as to the terminology. Some say "backing it in" and some say "loosing the rear end" when talking about corner entry oversteer. Can someone clarify please? Hope I didn't tick someone off because I can see how someone can take this post as insulting, but please, it is not my intention. Thanks Noam
  12. Thanks for clarifying I indeed meant 100% according to traction. I believe if any of us pressed as hard as we can on the brake lever, the bike would either lock the front (if applied too abruptly) or the rear will come up over the front of the bike and the rider fly over the handlebars. So obviously - yes - 100% of the capability of the bike. If I understand correctly, unlike in a car which you can easily exceed the traction of the tires under braking where either the ABS kicks in or if no-ABS, the tires skid, on a motorcycle with decent track slicks the limit of the tire is actually never reached. Assuming you properly load the front. the rear of the bike will start coming up. This will almost always under dry conditions with good tires be the first thing that will happen. At this point, if you brake harder, the rear will come up higher and higher until it can just go over the front. Ideally, max brakes is when the rear tire is just barely off the ground - maybe 1/8th of an inch. In racing like motogp they seem to not brake at 100% but more like 98% leaving if I had to guess about 5lbs of weight on the rear tire because if the rear is off the ground, risk in increased and the bike become more unpredictable than it already is. The longer the wheelbase of the bike, and the lower C.G., more forward G's have to take place before the rear starts lifting off the ground (100% braking). That's why in a documentry about motoGP I saw called "fastest" one of Rossi's techs states "max braking of a bike is 2.5G's". He's not speaking of what the tires are capable of, but he knows the wheelbase and C.G. of the Yamaha and can tell you at 2.5 forward G's of deceleration, the rear end comes off the ground at which point, you can't brake any harder (unless of course the rider can scootch his butt farther back on the seat which is very limited because the arms still much reach the handlebars). I am going to install my data acquisition system from my racecar onto my bike and will be able to see on the laptop how consistent my braking force is while blipping the throttle. I'm certain I'm not reaching 100% because my rear end doesn't feel weightless under braking.
  13. If I can use softer braking force during the last phase of braking, it only means one thing. It means that I could have braked later and used 100% braking force (until the trailing zone begins). There is the same problem with cars which is better documented since there are alot more books about driving fast than riding. In a car, the technique is called heal and toe. While braking, you use the right side of your foot to blip the throttle for the downshift. The books and multiple authors are aware and note that the driver's ability to maintain constant brake pressure while blipping the throttle is reduced. For experienced racers it's less of an issue, but it ALWAYS IS. So if I'm in a car without ABS braking at 100% and I blip the gas, I would personally err on the safe side and release 5% pressure off the brakes while blipping. Because if I screw up and accidentally apply an extra 1% of brakes, my wheels will lock. So going from 5th gear to 2nd, I blip 3 times in a car and each blip I go to 95% of max brake which costs about 1/10's of a second for that particular zone. So the authors recommend skipping gears in a car which allows the driver's right foot to focus 100% on the braking force and the sensitivity it requires in order to achieve 100% brakes... I rode my BMW Hp4 the other day and slowly started testing out its slipper clutch. I can do 80mph, pull in the clutch, RPMS at idle, pop to 2nd gear and JUMP off the clutch, it I barely feel anything. It sounds just as if I SLOOOWLY released the clutch. So you're right - my r6 slipper clutch stinks. I'm all about blipping while braking and 95% of the time I do it pretty good. 4% I mess up and 1% I totally screw up and fail to blip at all - for that, it would be nice to have a good slipper to save my butt.
  14. Good to know! I'll investigate this and probably buy this racing slipper clutch. It's a safety thing in my opinion...
  15. Maybe you should do all hard braking first and start with downshifting only during the last phase of braking, which should never be 100%. Two more useful articles: http://forums.superb...p?showtopic=258 http://forums.superb...p?showtopic=310 The only time I shouldn't be at 100% braking force is once I start leaning the bike and trailing off the brakes. So You are saying I should do my downshifting during turn entry phase? Sounds scary...
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