Dissident
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Posts posted by Dissident
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Well, at high speed, by the fact that it takes so much more energy to turn the bike, it's not possible to "flick" it over as quick, and if you watch the motogp riders in fast corners, it can seem that they are turning slow, but if you put an average rider on a bike and told them to steer at that speed, you'd seem them do it muuuuch slower.
If you don't think they do it quickly, like Greg said, watch them in a chicane and see how fast they go from one side to the other. When I took STAR school with Jason Pridmore and rode on the bike for two laps, I was shocked how quick the chicane turn was. For me as a relatively new rider at the time, I felt like I barely had time to pick the bike up from the one side to the other in the chicane, and yet I was going way slower then him. When I rode on the back, I realized that even two up, he was picking the bike up, grabbing another gear in the middle, and then flicking it over to the other side in less time than it took me to do one part of it!
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The engineering calculation tells that 1 horse power can move 7 lb at 53.57mph.
If there is wind resistance of 1 lb. Power needed is (7 + 1 ) lb x53.57x5280 ft/3600sec = 628.55 lb ft /sec; or is 1.14 hp
As speed increases, so is the wind resistance--(increases as square of wind speed). Say at 100 mph, the wind force is 50 lb (just guessing). In order to move a 400 lb bike plus a 200 lb rider (big guy) at this 100mph, not taking into account rolling friction at tire etc. It will need (50 +400 +200)lb x 100 (mph) x5280 ft/3600sec=95333.3 lb ft/sec; or 173.3 hp. (say this is the bike's max power.)
Now the same rider has the slim girl friend as passenger, say 100 lb. Assume wind force is less, say 40 lb (just guessing again ) at lower speed, say 87.84 mph. Now with the girl friend, if traveling at 87.84 mph, not taking into account rolling friction at tire etc again, It will need (40 wind +400 bike +200 rider +100 girlfriend) lb x 87.84 (mph) x5280 ft/3600sec=95335.7 lb ft/sec; or 173.33 hp. It is reaching the bike's max power.
The guy with his girl friend can only travel at 87.84 mph, but himself alone at 100 mph with the same bike.
Above is simplified and try to illustrate principle, with a lot of guessing........A 173 hp bike will run faster than 100mph, but for sure cannot run as fast with additional weight.
No wonder why everyone wants a MotoGP bike with 300 hp when he/she gets a girl/boy friend as passenger.....just want more hp.
You dropped a unit in your first euqation here:
(50 +400 +200)lb x 100 (mph) x5280 ft/3600sec=95333.3 lb ft/sec. Taking the numbers out leaves:
Mass x Velocity = Force
lbs x mph = HP
But the equation is F=ma, or m X a = F:
Mass x Acceleration = Force, so you should have
lbs x (mph)^2 = (HPxtime)/Distance (Horsepower isn't equal to Force.
Power is the product of force and distance over a period of time, or
Power = (Force x distance)/time, so rewriting for Force:
F = (Power x Time)/distance
So far, we still haven't solved for speed or drag
Think about it this way, a Suzuki Hayabusa is 100 lbs heavier than a gixxer 1000. Even if you have a highy modded GSXR 1000 making the exact same hp at the rear wheel as a hayabusa (let's say 180 HP for both), and they are geared the same, the Hayabusa will have a higher top speed because it has less drag.
This site explains it better than I probably did:
http://craig.backfire.ca/pages/autos/drag#accel
Notice that the top speed is a function of when the power available from the engine is no longer sufficient to overcome friction from drag. No weight factors in at all
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I did, however, see calculators that would give you your new top SPEED for a given horsepower if you reduce the weight, which made a LOT more sense to me.
For fun, I ran the calculation for my bike, which was just repaired, taking the horsepower (measured on the dyno) from 93hp to 112hp. The math says I should get about 10mph additional top speed. I'll be taking it out Saturday and I have a GPS laptimer, which has my previous top speed stored. I'm going to measure the new top speed and see how close it is.
So, for the sake of science and supporting the Forum, I'm planning to go out and ride the thing as fast as it will go. It's a tough job, but somebody has to do it...
The confusing part is keeping speed and acceleration separate. Speed is how fast you are going and acceleration is how fast your speed is changing. Your first sentence should really say "you can get more ACCELERATION from the horsepower you have, because you are pushing less weight."
Put it this way; if you try and lift a 50 lb box very fast, you can do it at a certain rate. If you take lbs out of the box, you're not any stronger than you were before, but you can lift it faster, right?
Mass/weight will affect your acceleration, but shouldn't affect your top speed much; only how long it takes to get there. The 7lbs = 1 hp is a good "rule of thumb" to figure out how it will affect your acceleration, but your speed is a function of actual power; (horsepower - wind resistance) multiplied by time. (This is the same reason two objects of identical shape will fall at identical rates even if their weights are not the same: here's the physics I don't want to copy into the thread: http://www.grc.nasa.gov/WWW/K-12/airplane/ffall.html )
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Ahh, here's the diagram I was looking for: (with that said, I would think sitting lower would make it easier to initiate the turn since the cg is closer to the axis of rotation). I've also seen similar stuff in some european mags
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Here is a little demo you can do that I've seen Dylan do: take a chair, and hang off it a bit, and at the same time, bring it to the balance point on the inside legs.
Observe what happens when you shift your upper body weight (not lower body) over the top of the chair (counter leaning it). Then shift your upper body to the inside, all the while keeping the chair at the balance point. Observe what happens to the "lean angle" of the chair (bike).
What do you see?
CF
Wouldn't that analogy be more applicable to making a slow u-turn with the bike, where you're not trying to add a large centrifugal force to get the bike to change course (turn instead of going straight)?
The experiment I've done is sit on the supermoto and go around a corner, and then stand on it and go through the same corner at the same speed (as far as I can tell, the bike doesn't lean nearly as much if I take the corner standing up.)
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Yeah, there's a few things going on in this question. I suspect some people turn like that for the reason that hubbard stated; to actually turn later and take more of a "race" line. Some might be doing it to load the suspension up, and I suspect other people do it cause they are not comfortable turning a car (like when you see someone not going fast but turning a small car REEEALY wide for a turn that isn't that tight)
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who doesnt' love a great article written by a great teacher!
I always thought a higher CG actually meant you had to lean the bike less, and that the purpose of hanging off was to move mass inward towards the radius of the turn, also meaning you can lean the bike less?
I know there was a thread on here earlier (found it while I was searching for the article I read awhile back and couldn't find)
http://forums.superbikeschool.com/index.php?showtopic=500
I always figured the reason riding twisted up doesn't help matters is that it often puts your head over the center line of the bike, instead of towards the inside. It seems like, if I'm on the supermoto and I sit on top and lean in, I don't lean the bike nearly as much as if I get low in the seat and hang off, too
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It's about right from what I've always heard.
It's always disheartening to see a guy 100 lbs more than you pass you lol
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I'm gona be doing my 1st track day in less than a month.. So I figured I start to get the suspension dialed in.. I ride an 08 zx6. All stock, with a GPR stabilizer added. How would you recomend setting the front and rear suspension for a 6' tall 145lb rider. I consider myself a fairly agressive rider? I know there are many variables to take account for but seeing you guys seem to use the same bikes I thought maybe you might have a good starting point for me..
Thanks in advance..
(Hopefully you can get some answers on ride height and such, but once you get that...)
Start with setting the sag:
http://www.superbikeschool.com/multi-media/sag.php
You'll need a friend or two, and I would do it while wearing your typical riding gear when you sit on the bike.
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Dissident - I think I need your motto tattooed in reverse on my forehead so when I look in the mirror it will all make sense - ie, as soon as you stop Trying to go faster & ride better then, from past experience, the speed just naturally follows......... I know this, I just somehow need to remember to actually DO IT !
One of my friends had one thing written on his bar pad on his supermoto during races (not sure why he was lookin down at it anyway, but..), and all it said was "RELAX!!"
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Hi Guys - I'm really impressed with the quality of the replies here & the thought that you've all been putting in to help me with this - it's very much appreciated.
So to answer some of these recent questions -
Fossilfuel - right, right & right again - I need a plan - the fundamental problem though was that I didn't know where the basic errors lay in order to formulate a plan.
Jailbait - hmmm - yes, well observed = not much fun
Cobie - no, I have never done any of the CSS - only read the books & got the vids. I would not be averse to doing them at all, but first I think I need to get right some of my more basic errors. BTW - I have since worked out where I have been going wrong, but more of that in a sec.
Dissident - I think I need your motto tattooed in reverse on my forehead so when I look in the mirror it will all make sense - ie, as soon as you stop Trying to go faster & ride better then, from past experience, the speed just naturally follows......... I know this, I just somehow need to remember to actually DO IT !
agreed - knee-draggin never made anyone faster - I just luurve the sound !
So...... Quiet house - no-one around - & re-played the "video" in my head of a couple of laps round cadwell....... jeez - I'm even making a hash of it in my head !
Revelations ! - my problems had very little to do with actually falling off - I just had nothing else to "pin it on".
the crux is that on corner entry I was concentrating on - (looking at
) - the turn-in point to the exclusion of all else & not looking thru the corner early enough or far enough ahead - leading to a sort-of domino effect then of not countersteering hard enough/fast enough & "Too late on the gas" . It's amazing how one simple error multiplies all the rest. Looking back on how I used to ride the same track until very recently, I can see straight away where I am now going wrong....... and sure enough, trying to ride faster isn't helping at all.
The mystery for me is that it was all-so-obvious (in hindsight) - - - great thing, 20:20 hindsight.
Thanks again guys & if you have any further comments on my analysis of things, I'd be glad to hear them.
Ian.
Pretty good summary; it really is a domino effect. You find one simple thing you are doing wrong, and you start backing into how to change, and realize you end up changing almost everything! Like, Ok, this session, I'm going to work on turning quicker.
Done. Ooops, looks like I know have to change my entry point. That changes your speed, and your braking, and calls for further adjustment, and so on. And in the process of all that, you're likely to find something to change.
I usually try and pick one thing at a time to work on during a session, but I always take at least one session mid or late day to just go out there and focus on.. Just riding. Let what I've worked on sink in a little and just be smooth and ENJOY it! Sometimes I do this earlier if I feel like I'm having an "off day" and not being consistent and feeling like I'm getting everything wrong (which usually puts me at the point where my survival reactions kick in; it can really snowball from there)
I'll be honest; I had a bit of the "go slow to go fast" revelation while I was go-karting one time. There was one corner I JUST couldn't seem to figure out, then under a full course yellow, I was just going slow through the course, and instead of coming out of the the turn before at 100%, I cam in at maybe 70%, and suddenly figured out the corner before (and my exit from it) were what was keeping me from seeing the right line into that (much more important) corner before the straight (but that's another topic altogether; putting all the corners together at a track instead of treating each one individually...)
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Cobie, you have mail.
Excellent. Been gone a few days, I'll get to that and back to you later today for sure.
Anyone else? Now is a good time to get me an application. Even if you aren't ready now, best to do the application, and if you are a good canditate, can let you know what steps are needed.
Here is one thing: most of my full-time coaches over the last few years didn't pass the tryout initially.
Best,
CF
As you know, I'm working on it
We'll talk again when I get a chance to sign up for a school!
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Well, I can understand your feeling completely. I had a big crash a few years ago and I was never sure exactly what happened. As it happens, Cobie spend about two laps riding behind me, then procedded to tell me my biggest bad habit and what it could cause (and went on to describe exactly how I crashed; mystery explained!). Turns out I've been adding lean angle and throttle at the same time, and none of the other schools I've been to had happened to point that out to me.
Personally, (and this may sound cliche, but it really works for me) the one thing I've learned about getting quicker is... Stop trying to get quicker. I know when I go out and I feel off the pace, the worst thing I can do is TRY and go faster. If I focus on just being smooth and maybe pick one thing per session to work on, I find myself coming back up to pace.
And the amount you drag knee isn't a great indicator of your speed; I used to drag more when I rode crossed up than I do now.
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I've used those tires a lot and I like them. I have an '06 gsxr-600. I've also used the same tires on a YZF600R.
How worn out are they? I've found that on any tire, if I use them on the street a lot, there's a certain lean angle I'm comfortable with on the street, and the profile of the front tire eventually develops a flat spot at that lean angle, which messes with the handling. When at that lean angle that's using the flat spot, the contact patch is wide, and that makes the bike want to stand up, but then when it gets passed that angle, the contact patch is narrow again, and that makes the bike want to lean down more. Seems like what you are describing. Even though my rear tires usually wear out twice as fast as the fronts, I usually replace the front tire with the back for this reason.
If you are used to some other tire then it could be the profile. They do make the steering feel a little different from other tires but I never had the feeling of it about to lowside. You didn't answer what pressure you are running. I run them about 30 on the track, but sometimes a lot higher on the street.
I wonder if your problem might have something to do with suspension? Cornering forces will cause your suspension to compress. Maybe you should try increasing the preload on the front. Have you ever checked the sag?
I've experienced the same feeling, and chalked it up to the same theory. New tires was the cure for me.
I did my first track day on street tires (Metzler M1s) and they gave me great feedback, and I could tell by the end of the day when I was starting to push them harder and started to feel them move around more.
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As I have seen with lots of top riders, their biggest ongoing breakthroughs come in their ability to use their visual abilities, their perception of location. Why can a rider go through a turn 300 times and all of a sudden have a massive breakthrough and finally "understand" the turn? It happens all the time. I hope it has happened to you. If it hasn't then I know why.
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Keith Code
ⓒKeith Code, 2005, all rights reserved.
I found I tend to have these "AHA!" moments when I [used to] least expect them; end of a session on a cool down lap, or yellow flags during races.. Those moments when I ride (or drive) at a slower pace then normal, but still brisk. The slightly lower pace let me devote more attention to just the RPs I was already using, but to look around and possible visualize different lines, or think about where I could put a couple corners together differently than I do when I'm riding at race pace.
I think this also made me realize that if I ride at maybe 8 or 9 tenths instead of 100%, I ended up being smoother, faster, and more consistent (perhaps that's a little redundant). I think during those moments are also when you find out things like, perhaps putting too much emphasis on one corner, to the point where it is messing up your entry to the next corner (which might be a much more important corner before a long straightaway, for example)
I also just finished reading the Rossi book. Just thinking about it makes me want to go out and ride
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I've posted a little here and there, but I tend to post slowly until I get a "feel" for a message board, see who the main contributes are, etc.
Expect to see more from me in the future -
Ah, yes, Willow. At my first race there, it was 118 in the shade, and the EZ-ups were melting into the pavement int he pits. Then the 60+ mpg wind picked up and took a good many out.
At least the winds aren't as bad on a sportbike as they are on a 260 lbs supermoto Especially when you land 3 feet over from where you were expecting!
)Nothing like siting in the office 4 days later thinking about the track to make you want to be back already! Wanted to possibly take the school this weekend but it's too soon, so it looks like I may go out and play in the dirty this weekend
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It was a fun weekend despite the winds. Too bad it was windy on sunday; I actually like that direction better but had to go a bit slower to compensate for getting blown around a bit... Still had a good time though.
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Well don't keep us in suspense, ask away!
C
I'm putting this in a new thread. OK, my bike ('02 Honda CBR600 F4i) is completely stock, which doesn't bother me that much- I'm not wanting to spend lots of $ on it, I'd rather spend it on school and track days to make me a better rider because in the end I think that gives more bang (probably a bad word choice) for the buck.
What would you folks recommend as additions/corrections; this is my guess but if I'm missing something, say so:
- stomp grip?
- frame sliders?
- steering damper?
- rear sets?
- bike stands?
- suspension parts?
I have put Dunlop Qualifiers on it and I'm happy with those. I haven't done any suspension adjustments although I haven't had any problems that I've noticed either. I do ride street and track.
IMHO Frame Sliders are a must.
The next thing I would would do is dial the suspension in. If you google it, there are a few articles on how to set sag with a couple friends and a tape measure.
From then on, I'm a big fan of spending most of the money on trackdays/school and good tires. If you find issues from then, address then as needed, but if you are not running into the limits of the stock suspension, brakes, etc, I wouldn't bother spending the money on them. The stock stuff on bikes today is probably better than the race equipment on bikes form not too long ago (well, maybe, but it's certainly good enough for most riders)
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Hello all. Been lurking on here for awhile and posted a thing or two lately, so I thought I'd say hello.
I've been riding streetbikes for awhile, racing a little supermoto when I can afford it, and I get to the track as often as I can. I've taken a few schools, and while I have yet to take superbike school, I have cornerworked for a few of the 2-days camps, and I'll be there this weekend in Vegas.
Oh, and I ride an Aprilia RSVR and a Husky 450SMR; I seem to have grown attached to Italian bikes
-Paul
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I'm biased because my current bike is an RSVR, but I find it's a surprisingly good track bike. The only place the big inline 4s will put any distance on you is straights, but I think the RSVR handles better than most of them AND seems to have more midcorner stability than the japanese bikes I've ridden (at least, compared to Yamaha R1, Gixxer 750, RC51, and a c ouple others). And while you are down on a power a little bit, it's smooth enough that you can get on it pretty early. The stock "slipper" clutch is pretty forgiving too and can make up for a little bit of uneven rev-matching. All that ads up to a rather forgiving bike that is pretty easy to throw around for it's size.
Of course, my other bike is a 450 supermoto and I'm even faster on it on most tracks, and being able to throw that around, both on trakcs and in the dirt, has definitely helped when I get back int he RSVR. The nice thing about smaller bikes is they are less intimidating, but since they are lighter, they also tend to not msk as many bad habits as a bigger bike can
) - the turn-in point to the exclusion of all else & not looking thru the corner early enough or far enough ahead - leading to a sort-of domino effect then of not countersteering hard enough/fast enough & "Too late on the gas" . 
Expect to see more from me in the future 
)
Rossi Sticking Out His Leg - Why?
in Cornering and Techniques
Posted
This weekend, it looked like the the later he was braking, the more he did it. The announcers said "even the riders don't know why they do it, but they say it just feels better"
It looked like a few toughed their foot a couple times on the ground! :-o And it almost looked like it made Lorenzo (I think) lose it when it happened...
it's odd, but it looks like more and more riders are doing it now.