Jaybird180

I saw the braking action and thought he got real lucky...again.

Welcome.

On the clips of smooth riders, the throttle application is also very smooth. The R1 rider as well as the black dude rolled off the gas when the rear began to slide. The guy on the Duc rolled out & straightened the bike just before his near miss of the road sign. The guy on the naked bike (Aprilia maybe?) was on the rear brake on corner entry and it looked like the slide there was intentional. Too much throttle could cause excessive rear tire load.

You bring up an interesting point. A rider COULD cause loss of rear traction by inadequate roll-on. Seems counterintuitive to the pedestrian.

I don't know why the rear tires are sliding in that video but the common thing I see just before the slides is a movement in the riders head&body back to the centerline of the bike. I'm wondering what's going on with that R1 as everything shook including the fairing stay.

The rider's position on a unicycle means that the rider must exert more force on the single tire whereas on a bicycle the outstretched rider can use both tires. Yes because the motorcycle is turning about the rear wheel's circumference Centripetal force. In the rain we cannot get the same level of friction from the road surface and therefore cannot generate the same load safely. I'll give this some thought and come back to this one if you don't mind as I believe that bicycles don't quite behave the same as motorcycles due to the bicycle having similar tires on front and rear....Okay I've thought about it- It's centripetal force Lean ange is cause. See #2 Excessive acceleration. Controllable by modulating the acceleration until Balance Point (BP) is reached, afterwards it's subject to the laws of gravity if BP is exceeded Gravity and Engine power is forcing the rear wheel into the ground, until a certain angle as determined by swingarm angle and wheelie angle, which might constitute the Balance Point

That's the point where you've made it clear.

Yeah maybe. Whatever 3rd gear at WOT gave me on my 600 on my knee.

I had a day many years ago of trying to spin up the rear at full lean. I wasn't able to get the tire to break traction. In hindsight, I may have been in too high a gear, though it seemed right for the drive out of the turn once the bike was vertical.

I think you’re getting into a question of chassis development. Engines can be evaluated objectively as we have the ability to measure power output. It’s the engine/chassis design that makes drive ability. i suppose chassis designers might have an objective measure of performance but I intuit that it’s subjective. Take out the man needing specific characteristics and you’re back in the old days of the do-it-all bikes with frames that are simply structures that hold all the parts together.

This is the article to which I was referring. LET ME KNOW if this answers the mail http://www.motorcycle.com/ask-mo-anything/how-much-faster-are-new-motorcycles-than-older-ones.html Edit: Probably not, but getting closer. Here's one about 30 years of tire development: http://www.motorcycle.com/ask-mo-anything/how-much-better-are-tires-compared-to-30-years-ago.html Sorry, this is the best of what I've got to help in your search.

I know such an article exists. In fact the article started by a reader asking a similar question to yours and the response started with an appraisal of the data collected over the years on so many different bikes. They did an analysis with an attempt to remove different riders from the equation to see if bikes really have improved objectively. Clearly the newer bikes fared better but they didn't take the most important factor into consideration in their "scientific" analysis: Rider Improvement. I wish I could find this for you as I think it's what you're after. I don't even recall the source but I'm certain I read it online and since I don't have a paid subscription to anything so it should be publicly available.

Do you know what profile & size tire Dani Pedrosa uses? Specifically the rim width? You may wish to gather all the facts before setting your bar.

I've seen "Faster" and have it in my collection as well as the follow-on "Faster and Faster", but now you tell me about "Fastest"

Wish I could find some footage. I don't think it was dragging elbows as he's (Marc Marquez) known for but yet still significant. In the OP I linked to a request from Cobie to find footage of Schwantz doing similar. His recollection was 35-40 degrees.

@Lnewqban I love the way you explain things. It often takes discussions to basic math and physics and that's a good thing as it leaves rider error out of the discussion. If you don't mind, I'd like to make an observation in the hopes that it will untangle this discussion. In order to turn a motorcycle (at speed) it has to lean. Agreed? If this is true, the act of leaning and turning are 2 separate behaviors and are about different planes of motion. The leaning would be a roll about the longitudinal axis and turning would be a lateral movement or yawing motion about what is often referred to as Z- Axis. But these are still 2 separate changes of state of motion. Agreed? Secondly, Speed through a turn DOES NOT (by itself) make a turning limitation. Controversial, I know.... I'll go on record as saying that because there is a limitation to how far the bike can be leaned, there is also a limitation to how much pressure can be applied to the road/tire meeting point and therefore the tire will slide as we approach the limits of current technology. I think the math used in example #3 has a very limited circumstance where it applies, but I get your point in that it would be the losing way to negotiate the corner in your example. To do the math backward to limit the entrance speed would be a good example of what happens with a ham-fisted rider - he'd cause all types of problems with low entry speed and trying to make it up on the gas... I'm just asking the question: if tire traction is stable, and we take the same line, same entry speed, get on the gas at the same point but instead roll it harder, sufficiently enough to lift the front will we have gained a better result. I think, yes. And if this is true, why do we need to be concerned with limiting our roll on while respecting tire traction limitations?

MM93 has been seen doing this as well as Aaron Yates.

I'm sorry that my forum coding skills don't work well with this software (and I can't get into an advanced mode to edit) and I hope that what I was trying to say is clear enough to get me straightened out.

Thanks for the suggestion to re-read some material. I'd come to that same conclusion as I began thinking this through on my way to work this morning. I do need to talk through some things as I read and also some thoughts: In Ch 2, the section on throttle control, one of the margin comments mentions that it's possible to get on the gas too early and cause the bike to run wide. In light of my new understanding of what the rear does in a corner, in that it's the dissimilar circle size on the side of the rear tire that causes the bike to turn I now ask :does the (greedy) application of throttle really cause a bike to run wide while leaned over? We already have observed that we can lift the front with throttle and the bike will remain as sure as if on rails. Ch 2 also give the reason for the idea behind the 60/40 and that it's based on a comparative measurement of footprint, nothing more. 0.1-0.2g of throttle is what's needed to maintain that relative contact patch. But since we now understand that size of contact patch isn't the determining factor in available traction should maintenance of footprint still be a Primary concern as requested by Ch2? I'd like to make a note here: I'm not advancing an idea of "whacking" open the gas, nor am I saying that a smooth roll-on isn't the right thing to do. I am saying that perhaps we needn't be as gentle with the throttle as I previously thought. If this is really the case, then perhaps I opened a door for more available attention for other things. I hope I'm not opening the door to more highsides. 3. Donny Greene in his comment at the end of Ch 3 says it this way: "Once you have the throttle control rule firmly understood and practiced and you can get the rear wheel spinning with a smooth roll-on, your bike will handle again." What if instead of spinning the rear, you time your roll rate so that the tire is hooked up and driving forward? I can see a viable reason to want to use a spinning rear wheel to help finish the corner, but it might be too much mid-corner even if it does work just fine for Casey Stoner.

Still haven't found it yet, but you can chew on some of this data. maybe copy/paste into a spreadsheet??? https://www.sportrider.com/tech/sportbike-performance-numbers

This is pure speculation but I'd imagine that the front wheel begins to lift at a point well above 60% weight distribution. But if you could instead find a balance point where all of the power being used it for propulsion than lifting the front wheel, where would that be in relation to the ideal 60%?

One the bike is on trajectory, we don't need the front anymore. The rear tire can support the full weight of the rider and bike combination. The power applied extends the suspension and yes the load to the tire increases. Fortunately, friction is directly related to load applied so therefore the load resists the tire sliding. Assuming we're talking about fresh rubber and not concerned about longevity, why do we care about having 40% of the load on the front. Why not get the power to the ground to the maximum that it translates into forward motion?

Just tossing this out if anyone has seen this. I found it on Amazon Video and only intended to watch the first 30mins or so but found myself staying up late to watch the entire 2h 18mins. It was awesome and I thought well put together and showed some of things the behind scenes story of 6 Aliens of MotoGP. One part stands out is the statement (objectionable to me): “A fast rider can learn to stop crashing but a slow rider cannot learn to go fast.”

There’s an article with an objective performance data comparison of vintage vs modern sportbikes. Maybe later today I’ll see if I can find it again.

Is this what you meant?