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  1. Yesterday
  2. I know nothing about this topic, basically. However, when I attended a gravel rally, I was told to keep weight on the outside peg and push firmly against the fuel tank with my outside knee while turning standing up. For me, that helped massively. Suddenly, it was easy to steer with the rear using the throttle, and slides could be controlled. I immediately felt safe. Whether this mean anything for road racing I cannot say. I have also read many times over the years that top rank riders can shift their weight between the inner and outer peg up to 20 times in a single corner. Apparently, they do this to control drift and grip. Way beyond my scope to try - I'd likely crash right away because my limited mental capacity would be spend on dancing on the pegs rather than controlling the bike and reading the road. Finally, riders like Tony Elias and other shorties commonly let their outside foot dangle above the peg while cornering, a result of hanging way off and having short legs, I presume. They still win races. So perhaps this is just another tool available to be used by the rider, but not mandatory for success?
  3. Yes, I’ve looked into cutting the cord and streaming options. It does appear getting BeIN through Sling is the most economical option ($60+/yr), if the goal is solely being able to watch MotoGP. Unfortunately, for our house, cutting the cord isn’t an option (many out of market programs only available through our current provider). Also, there’s a big difference between race coverage on BeIN and MotoGP/Videopass, which offers access to free practice, press conferences, races going back to 1992, etc. I was simply wanting to inform the people on the forum that there’s a discount for Videopass currently available.
  4. Have you looked into/considered TV streaming options? I know via my Fire TV I get enough that I don't miss cable tv.
  5. Last week
  6. Wanted to share: @motogp on Twitter is offering 10% off for this season’s subscription - via the link found there. That plus the current $:€ exchange rate makes this season $136.27 vs the standard price of $159.99 (when you see it offered in $’s).
  7. I have been told that weighting, or rather pressing down on the outside peg allows you to corner faster and safer, as it encourages you to put your head and shoulder weight, and not your butt, inside the turn (aka: kissing the mirrors), which requires less lean angle in a given turn/curve. (Your upper body weight leaning into the turn replaces some of the bikes weight it would use in the lean, requiring less lean angle on the bike) Ive taken turns where it seems the bike stays almost upright, and I'm able to hug the inside line nicely in the apex of long curves. It helps as well as it puts an outside downward force to the rear tire for stability/traction. I havent been riding a long time, but I have been testing taking turns in this fashion, and it definitely seems to help me.
  8. Sorry that's sort of what I meant -- if I'm on the 'edge of a penny' for contact patch then to lose traction I only need that edge of a penny to hit something without friction (and the keying/adhesion etc); with a larger contact patch then you have more of an area which would need to be disrupted in order for the maximum grip to be reduced.
  9. Earlier
  10. One thing I’ve read about is that DOT certification is a manufacturer assertion.
  11. yakaru, I'm not sure it is as much a question of friction being applied in more places (unless more 'keying' is happening) as it is the extent to which the contact patch 'coefficient of friction', at that particular moment in time (so factoring in the portion of the contact patch that has been disrupted) has not reached the point of 'slip'. In some of the articles I've read the point of slip is expressed algebraically and can be calculated (theoretically) if all the other variables in the equation are known. Dave
  12. Thanks, Dylan. I've read about these dynamics in various articles but have never seen them summarized in such a succinct manner. Very helpful indeed. I would add I think 'keying' may also be a dynamic property (in addition to static) given the extent to which keying is constantly changing as tire energy dissipation, surface and interior heat, abrasion / shearing stress, and load change. For those who may be interested in the engineering details, one of the websites I found helpful is multiscaleconsulting.com. In their publications section are various papers on rubber friction and contact mechanics. A warning - their papers are filled with lengthy algebraic formulas supporting their analysis. I try to just focus on their key points and not get lost in all the math. I think the next evolution of this for me will be to learn how to read a tire so I understand what is happening to it and my traction/friction equation. Dave
  13. If this has already been stated I apologize -- but I want to go back to the 'tug of war' example. Let's make it a bit more of a "water ski" example where you're being drug along on a rope and resisting by putting your heels into the ground. In isolation it shouldn't matter if one or two heels are dug in, however, if something in the scenario happens where the grip of one heel is jostled loose then you immediately face plant. With both feet any scenario on one can have the 'load' taken up by the other during recovery. In a similar way, a larger contact patch allows the friction to be applied in more places should there be any disruption in another?
  14. Your collection of data and research shows you are barking up the right trees. Here's some more data regarding tires: Per the Dunlop engineers tires grip in 4 ways: 1) Adhesion--the temporary chemical bond between the tire and surface. 2) Keying--the tire deforming and filling in all the nooks and crannies of the asphalt or squishing into the depressions. 3) Abrasion--the tire tearing from itself or wearing away. 4) Hysteresis--the energy storage and return by the rubber and partial conversion to heat. The first two can be looked at as static properties and the last two dynamic properties in my opinion. I'm still learning on all this stuff and when talking to the tire engineers, they don't have all the answers either. Heck, aviation engineers still can't all agree on exactly how a plane flies through the air!
  15. I've been trying to develop a better understanding of traction over the last couple of months as well. As such I've read a number of articles and technical papers about friction, and specifically, friction as it applies to the interaction between rubber and hard/asphalt surfaces. As I understand it, there are four types of friction: static, sliding, rolling and liquid. I may be wrong but I think the Amontons-Coulombs three laws of friction do apply to tires/rubber as it relates to "static" friction - tires may not be rigid but they are solids. However as soon as you move to sliding and rolling friction (which are the only applications we really care about) the three laws need to be modified for rubber specific properties and what happens between rubber tires and asphalt friction as heat and tire deformation change. Attached below are a couple of articles that help explain rubber-hard surface dynamics that cause rubber related friction to act differently. After reading these articles (and several others) I am now thinking about the "coefficient of friction" between tire rubber and asphalt, at any given moment in time, as being determined by the following ... For road surface … its material, texture, condition (including extent of surface oils/moisture present), temperature, gradient/camber. For tires … their material, construction, condition (also including extent of oils present), energy dissipation and resulting temperature (a hugely significant factor), stiffness, extent of flex/deformation and how well the rubber fills asphalt surface gaps and creates microasperity contact points (so yes, contact patch size matters), and finally tire pressure (which has direct impact on extent and rate of tire temperature changes and flex/deformation). Pressure or load between the tires and road surface … from both vehicle weight and riding forces (ergo cornering forces) The list may be missing a few things, but I think it hits the major elements. And since cornering force has such high impact, I think about the extent of "cornering force" being driven by a number of factors as well, including ... Weight Vehicle balance (shifting of weight, pitch and angle) Kinetic energy (speed) Corner radius and extent / rate of radius change (e.g. closing versus opening radius corner) Centrifugal force (directional inertia) Centripetal force (force acting on a moving body at an angle to the direction of motion, tending to make the body follow a curved path) Rolling resistance (from braking and accelerating forces) I'm still learning on all this (traction / friction) so feel free to correct me where I am off base. Dave Guidance-Rubber-Friction.pdf Rubber_Friction_and_Tire_Dynamics_A_Comparison_of_Theory_with_Experimental_Data.pdf
  16. Thanks very much. We have more on the way!
  17. faffi

    Then vs now

    Rutter is a multiple winner of IoM, so should be comparable. Sure, it was not set on the same day by the same rider, and as such not a perfect comparison, but it should give a fairly realistic picture.
  18. WHR

    Then vs now

    I think I need to donate my 1997 VFR750F to the school only on condition that it be built as a "demo" bike for students to marvel at it's awesomeness! :-) Seriously, I believe this is a bit like comparing apples to oranges, not to mention all the other factors involved. A better comparison would be the same rider (Rutter for example), riding both bikes on the same day.
  19. I can't answer your question, but I can tell you one thing. Snell approval is overrated. AFAIK, all it does is add $$$ to the cost of a helmet. "They wouldn't be DOT approved in the Asian market." They were probably not Snell approved either. That would account for the cost savings. I wish we could tag someone in a post. I'd like to know the school's stance on this as well. I don't want to assume they would, even if an ECE approval is above the DOT standard.
  20. Hey Dylan, I am sure you get this a lot, but..... Reading the information you put on the board feels like finding clues in mystery novel. Like a real-life Divinci Code deal, only for motorcycle addicts. I am still buzzing with the classroom time on physics, biology, mathematics, psychology, and the riddle of why motorcycles turn. I really appreciate your contributions here.
  21. faffi

    Then vs now

    For comparison, the premier class has seen less performance gains than the fastest class at Isle of Man (current lap record is set with an average speed of more than 135 mph) - in 1990, Gardner lapped Phillip Island at 1:34.560 during the race. Current race lap record is 1:28.108, set by Marc Marquez in 2013. If I take that equation, starting with 115 mph as an arbitrary average speed of Garner, I end up with 120.8 mph for Marquez. Interestingly, the best race lap in 2019 by Vinales took 1:29.322, or 119.7 mph using the same math. This is a rather flowing track where handling is more important than power, though, whereas IoM benefit quite a lot from more power. Report to moderator 188.126.196.22
  22. faffi

    Then vs now

    In 2018, Micheal Rutter punted a stock Panigale 1100 V4 Speciale the around IoM TT course in about 18:40 for an average speed about 121 mph. I say roughly because it is impossible to time the lap correctly since it is not a typical get-away, nor lap completion. But it is close enough. It's on YouTube in two parts, part 1 being here: https://www.youtube.com/watch?v=OYaSG_IoAXk For a stock bike, that seems pretty impressive. However, Steve Hislop set a 18:39.4 lap on an RC30, or the Honda VFR750R as it was also known, back in 1989. So what do you think? Is it impressive that 30 years later, an 1100cc stock machine on road tyres can match a 750cc modified street bike on slicks from the 80s, or would you have expected more from the development? As a comparison, the New Era 750 record around Phillip Island was set by Scott Campbell on a Honda RC30 in 2016 with a time of 1:40.719. The production Superbike lap record was set by Wayne Maxwell in 2018 in a Yamaha R1 with a time of 1:32.224.
  23. Dunno if anyone else has been seeing the articles about this one. Looks relatively close to the HP4R, spec sheet alone a little better but also even more expensive. Would be interesting to do a side by side but my instincts are saying I'd still prefer the HP given that the trial rides I did of the Ducatis at the track didn't really jive with me.
  24. Haven't ridden an electric bike yet but just to chime in some thoughts I've had before: There will definitely be some big advantages -- low end torque and no need to handle gearing lets you focus on the other skills more and gets performance wins. Given race scenarios the battery requirements also will lead to some really light track-oriented electrics at some point. But there's something about handling shifts that just feels like such a part of riding; I adore the BMW shifter blip but I still am making the trade off calls on when or if to shift (At CodeRACE last October I placed second by .002 because I shifted to 2nd while 3rd made the call to stay in 1st to avoid the risk of losing speed in the shift). I'm sure I'll eventually get over it as they spread but still
  25. Hi Roberts, Thanks for the insights. Very helpful feedback on center of gravity, velocity/comprehension dynamics, tire wear challenges, and the ability to lock in body position and focus with fewer physical action distractions. As CSS has taught us all, the less of our $10 of attention we spend on distractions the more we can focus on what matters (wide vision, throttle control, RPs, POT, hitting the apex, elevating our speed, etc., etc.). And the notion of a "constant sweet spot" is a pretty compelling idea. Thanks again. Dave
  26. Hi all, so to make it official I'll lay out the history. Born Oct. 1955, and before my 15th bday, I was lucky enough to buy my first motorcycle, a 1970 DKW 125cc Enduro. So I'm celebrating 50 years of being a motorcyclist! Raced a bit of motocross in the early 70 's, and bought my "real" first street bike around 83/84. Today my daily is a 2004 DL650, and I also have a 1997 VFR750, and a 2000 R1 of which both need work to get them back on the road. I enjoy working on my bikes. I've been a rabid fan of all types of racing, but of course motorcycle (MotoGP, WSBK, AMA, etc.) racing reigns supreme. Life (raising a family) interrupted what I'm sure would have been a grander life on two wheels, if I'had just realized sooner that motorcycles are my passion. But not to wallow in regrets, I'm going to make the most of my golden years by pursuing motorcycle challenges, of which taking a CSS class is one of. I'm a bit afraid that I'll get completely hooked and will not have the time or funds to satisfy my newfound obsession! :-) My profile handle "WHR" stands for Wild Heart Racing. Something I came up with years ago with hopes of someday using it in some fashion related to my passion. My given name is Tom.
  27. Thanks for the welcoming and positive input. Looking forward to it.
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