Effects of changing sprockets


UselessPickles

New Member
AS I said, REAL WORLD is very different to sitting there pasting formula's into Excel chump. If you were 100% correct, why do MotoGP, WSBK, F1, NASCAR and on and on and on, do REAL WORLD testing to PROVE their theories? please riddle me that?
If you re-read my post, you'll see that I never claim to be 100% correct with the results of any one particular run of conditions through the simulation. Only that the simulation is good enough that when two different scenarios are simulated to have significantly different results, that the relative difference must be a pretty good indicator of a relative difference you'd see in the real world. Simulation says that 2nd gear launch is 0.5s slower than 1st gear launch? That's definitely enough to be confident in the results.

Also, this is a bit more advanced than Excel formulas. It's custom software that I've written to simulate the significant forces involved at a time resolution of 0.0005s (that's 5 millionths of a second).

The climate change comment was quite a good one actually, its data modelling based on "science". In essence, its exactly the same as what you have been doing throughout this.
Except that "science" can't agree on precisely how weather/climate works yet, because we just don't know yet, so of course models are going to be inaccurate. The ideas that I'm modelling have been pretty well understood for quite a long time (mechanical advantage of gearing, friction, acceleration caused by force, aerodynamic drag) and the formulas modelling it have been proven to be accurate by "science" at the scales we care about for this purpose.

Do you want a full detailed explanation of how it works? Then maybe you could point out some significant factor I'm missing that makes my simulation unreliable.

If simply sitting there and punching drag coefficent's into a pre determined forumla was the winning formula why would anyone waste money doing the expensive real world testing?
Because they're not testing for simple things like "should I launch in 1st or 2nd gear with this engine?". They are testing things like "does this newly designed engine stay within operating parameters while racing and stay in one piece", "do these suspension adjustments give me better handling through the varying surface conditions and corners on this track": very complicated things that they need to confirm in the real world before going to a race.

BTW - they do use computer simulation to design the engines, chassis, suspension designs, etc. The real-world testing is to confirm the simulation results were correct, fine-tuning, etc.

I'm modeling something very simple: straight line acceleration assuming a smooth level riding surface. And I'm not going for 100% accurate real world perfection. It's the relative differences in results that matter.

So why dont you go to the drag strip your eagerly awaiting for, and prove your numbers? Scared they may not stack up the same? Do it...you know you want to.
Going to the drag strip by myself will only prove what I know to be true to myself, but won't convince anyone else. My capabilities, consistency, the track conditions, etc. would all be called into question. I would need someone who claims to have real-world capabilities of disproving my results to meet up with me to be involved in the real-world testing. But even then, someone could always call into question difference in rider capabilities, track conditions, etc.

That's kinda the whole point of the simulation I wrote: take away the question of rider ability, consistency, etc., and find out what relative differences are between different situations - the capabilities of the bike itself.
 
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UselessPickles

New Member
Are you not, by definition, shooting someone else's opinion down showing that you believe in your own exaggertaed abilities? lol.
Actually, no.

1) It's not a matter of opinion. The FZ6R either is or is not capable of launching faster in 2nd gear compared to launching in 1st gear. It is objective and testable. A person's "opinion" about it cannot change it. This is what is known as a "fact".

2) For you to claim that I am exaggerating my abilities, you would have to know what my abilities are. Since you do not know my abilities, and you do not know the abilities/limitations of the simulation I wrote, you are simply throwing out a baseless personal insult by calling me arrogant.
 

bmw675

New Member
Less :catfight:
More :hug:
 

ShockWave

New Member
Pickles, since you seem to be running the show here I was wondering if you could answer something for me (although anyone with info would be appreciated)

I'm thinking about dropping a tooth or two on my front sprocket to increase acceleration, but all the numbers you have shown seem to indicate that it doesn't make much difference. Then again I also realize that most of those figures are numbers to be seen at the drag strips or racing at high speeds. I don't care about my top speed because it seems to only get me in trouble anyways. I mostly care about how fast I can come off the line, and ease of passing on the highway. I also admit I love pulling the front end up, although I only do it in first gear and I never ride it for any distance. Essentially all of my ride time is recreational so highway RPMs don't concern me as long as I'm not redlining or in danger of damaging the bike if used continuously.

So my question is, would dropping a couple teeth off of my front sprocket benefit me on quick takeoff, or is it really not worth my time? If not, then how many teeth on the front/back would need to be adjusted for a real difference to be made? I know the FZ isn't known to be the fastest in the world, but I still love the feeling of twisting the throttle and feeling that power.

If it makes any difference, I do have a two brothers black series full exhaust, and a PCV tuned for that exhaust, and I have programmed the "accelerator pump" to deliver 15% more fuel for 30 revs in response to at least delta 40% throttle (or thereabouts) I know since I don't have the dyno run for it you can't give exact numbers, just looking for an opinion.

Also, I've had my bike for almost 2 years and only now have stumbled upon this site from google. I think I'm gonna like it here! And in reference to the s*#t storm going between everyone on the 1st vs. 2nd gear takeoff, pickles is right. if second is faster, you are doing something wrong, and I'm not talking about math or numbers, I'm talking about real world experience. I've heard the 2nd gear takeoff thing and have tried it, and I can confidently say that it was invented for muscle cars and people who don't know their bikes.

ALSO: I'm deciding between sprocket change and a high flow air filter as my "next" upgrade. I've had it dynoed before and it showed to be running quite rich, and while I'm told tweaking with the map would help, a new filter would be a better choice because the stock filter can't keep up with the lack of backpressure from the aftermarket exhaust. Wanted to know if anyone had any thoughts or recommendations?
 
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Boss_601

Elite Member

UselessPickles

New Member
would dropping a couple teeth off of my front sprocket benefit me on quick takeoff, or is it really not worth my time? If not, then how many teeth on the front/back would need to be adjusted for a real difference to be made?
That's a lot of subjective stuff in there: A "couple teeth", "quick", "worth your time", "real difference". Only you can decide :)

Back in my post where I list many simulation results, take a look at the various "soft launch" results, because that's similar to a casual quick takeoff to full throttle. Unfortunately, I can only model full-throttle acceleration, but part-throttle acceleration would have similar relative differences between different gearings.

The basic idea is that if you go with 10% shorter gearing, then you will have 10% more acceleration (at least at lower speeds where aerodynamic drag is less significant, approximately below freeway speeds), but the speed for any given RPM will be 10% less, so your peak acceleration in any given gear will come at a 10% lower speed, and you will reach redline at a 10% lower speed and be forced to shift up at that lower speed compared to stock.

The end result is a lot of stuff tricking you into feeling like the bike is WAY faster: at some point you really do get 10% more acceleration and the engine revs up through its RPM range much quicker. If you don't get the speedometer adjusted, then your speedometer reports 10% higher speeds than you are actually traveling, further exaggerating the perceived increase in acceleration.

In reality, you only truly get that 10% gain in acceleration in first gear below the peak HP RPMs. After that, everything mostly balances out due to the earlier shifts (see the chart in my first post).

BUT...

Everything I just said only applies to full-throttle racing, running up through high RPMs, shifting such that you are accelerating as fast as possible at any given speed. Things are different when you ride "normally" at lower RPMs significantly below horsepower.

In these "normal" daily driving situations you will actually get close to that 10% gain in acceleration from a 10% shorter gearing. Example: cruising at 40mph in 4th gear. With 10% shorter gearing, you'd be at 10% higher RPMs and have 10% higher torque multiplication, so cracking the throttle open will be somewhere close to 10% quicker. So for "normal" riding, it will be quicker, but if you were to race someone at high RPMs, you wouldn't be as much quicker as you would expect, and you might not be quicker at all if you did a rolling start in 2nd gear.

I'm deciding between sprocket change and a high flow air filter as my "next" upgrade. I've had it dynoed before and it showed to be running quite rich, and while I'm told tweaking with the map would help, a new filter would be a better choice because the stock filter can't keep up with the lack of backpressure from the aftermarket exhaust. Wanted to know if anyone had any thoughts or recommendations?
A custom dyno tune is the only way to guarantee you have a proper fuel map for *your* bike. I won't get into aftermarket air filters. There's plenty of arguments online about whether high-flow air filters (like K&N) are good, or whether they let too much stuff into the engine, among other issues. Either way, changing an air filter is not the correct way to solve a fueling problem. The correct solution is to tune the fueling properly. If a different air filter will allow more air to flow through the engine, and you want it, then go head and get it, but only a custom tune afterward will truly get you proper fueling. You might be "close enough" though without a tune, but it's still just an approximate band-aid fix to the fueling problem. All of this is really off-topic for this thread and should be discussed elsewhere.
 

Invader Jim

New Member
...Things are different when you ride "normally" at lower RPMs significantly below horsepower.

In these "normal" daily driving situations you will actually get close to that 10% gain in acceleration from a 10% shorter gearing. Example: cruising at 40mph in 4th gear. With 10% shorter gearing, you'd be at 10% higher RPMs and have 10% higher torque multiplication, so cracking the throttle open will be somewhere close to 10% quicker. So for "normal" riding, it will be quicker, but if you were to race someone at high RPMs, you wouldn't be as much quicker as you would expect, and you might not be quicker at all if you did a rolling start in 2nd gear.
I don't think that works for me because I shift more by ear than watching RPMs and thinking about what gear I am in. If I am someone that typically cruises at 5K rpm changing my sprocket is not going to change that. With different sprockets it would change the gear I am in at a given speed so that I am at the 5K RPM that my ear is used to. If I want better acceleration in cruising I just need to adapt my shifting to keep my cruising RPMs at 6K or 7K instead of 4-5K. As you said the 10% quicker comes in first gear but I don't see it making any difference beyond that if you shift by ear.
 
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UselessPickles

New Member
Yeah, if you adapt to your new gearing by often cruising in a higher gear than normal to stay at a "comfortable" cruising RPM range, then the increased acceleration available from shorter gearing will mostly be noticeable to you only when initially taking off in 1st gear. For that initial take-off in 1st gear, you can safely assume that a certain percentage change in gearing will give you about the same percentage change in acceleration, but only up to the point that you hit peak power in 1st gear.

So you have to decide whether it's worth it to you to get some additional initial off-the-line acceleration in first gear, but deal with shifting sooner (time- and speed-wise) and cruising at higher RPMs when your in 6th gear on the freeway. And don't forget about the cost of getting a speedo-healer or similar product to correct the speedometer.
 

MNGreg

waiting out winter
Elite Member

Marthy

World Most Bad A$$ 6R
Elite Member

Marthy

World Most Bad A$$ 6R
Elite Member

UselessPickles

New Member
Dang! You guys are still going at it??? Getting just as bad as oil and gas thread!

Bring it to the drag strip! Because as technical as it might be... it's all about the stop watch!
Not "going at it" still. I just noticed his E = mc^2 comment and found it quite amusing.

A somewhat recent thing that potentially disproved the theory of relativity (and therefore potentially disprove E = mc^2) was an experiment where something had been recorded as traveling faster than the speed of light. Others tried to reproduce the results, but never found anything traveling too fast. After further investigation, they found a loose wire on a timing device that had caused false results. Seemingly crazy/unintuitive effects of relativity (including E = mc^2) have been confirmed in many experiments.

I'd love to bring it to the drag strip, but that would require someone else to meet me there.

It's interesting that VRIIClubby's most recent reply has disappeared (the one that includes the awesome "Please riddle me that?").
 

MNGreg

waiting out winter
Elite Member

dart1963

Super Moderator
Elite Member

UselessPickles

New Member
I got a nice boost of confidence in the reliability of my simulation. My brother just bought a 2006 Subaru WRX STi and wanted to compare some things in my simulation. We found a stock dyno chart online, a measured coefficient of drag and frontal area, specs for transmission ratios, weight and tire size. Everything we needed.

First simulated run, launch hard at peak torque, assuming 0.5s shift times, and I got...

0-60mph: 4.9s
1/4 mile: 13.01s @ 104.4mph

One car website reported 4.9s 0-60, but no 1/4 mile time.

Another car website reported 4.5s 0-60, and 13.0 sec @ 103.5

So it all looked pretty good, except that 4.5s 0-60 time. Then I remembered that some car testers use a 1-foot roll-out (like a 1/4 mile race) when timing acceleration. So back to the simulation...

Simulated 0-60 with 1-foot rollout: 4.57s

Much better!

All the simulated results are close enough to reported results that slight variations in shift speed or launching skill can account for the differences :)

For example, reducing the shift time to 0.46s (just 0.04s faster) gets a simulated 4.5s 0-60 run with a 1-foot roll-out :)

This is making me happy, because I've been playing around with torque data from an upcoming supercharger kit for a Jeep Wrangler. My simulation predicts 0-60 in the low 5's and 1/4 mile in the upper 13's... in a Jeep Wrangler! Imagine how much fun that would be with the top down and doors off in the summer :)

And this is using data from an old dyno chart before fine-tuning. They're making about 20hp more with their final tune. They also showed off a dyno chart with an additional 30hp (50hp more than the simulation data) by using a tune for 93 octane fuel instead of 89 octane. Not sure if they're actually release a 93 octane tune though.

Now I just need to come up with $6k so I can buy this supercharger kit...
 

zcypher

Member
lmfao at the 2nd gear start thing. I've raced for years too in a variety of cars, and that's just hilarious. The only time starting in 2nd has been beneficial has been when NOT racing (easier to not slip in shitty winter conditions, sometimes). aside from the exceptions already mentioned (first is just unusable), starting in first gear is always faster. it should be pretty obvious ...

as for bikes, well this is my first one so i don't have immense experience to draw on there, but I have started in 2nd a couple of times and so far it doesn't seem like there's any way that could be faster than 1st... 1st is quite nice. :-D


Thanks for taking all the time to put all this together pickles. Been a great read!
 

ST3RL0

New Member
lmfao at the 2nd gear start thing. I've raced for years too in a variety of cars, and that's just hilarious. The only time starting in 2nd has been beneficial has been when NOT racing (easier to not slip in shitty winter conditions, sometimes). aside from the exceptions already mentioned (first is just unusable), starting in first gear is always faster. it should be pretty obvious ...

as for bikes, well this is my first one so i don't have immense experience to draw on there, but I have started in 2nd a couple of times and so far it doesn't seem like there's any way that could be faster than 1st... 1st is quite nice. :-D


Thanks for taking all the time to put all this together pickles. Been a great read!
To add on, starting in 2nd or 3rd is smooth but completely useless in racing

Sent from my GT-I9505 using Tapatalk
 

tho9504

Member
Is +1/+0 the same as +0/+1? Instead of changing the front sprocket, if i changed the rear with +1 with that lower the RPMs at cruising speed? The only reason i am asking is because if i am on the highway or something, i hate reving the hell out of my bike. and the rear seems like it would be easier to change than the front (dont have any experience, just a guess).
 


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