Optimum Shift Points

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UselessPickles

Making Grand Canyon replicas from air boxes...
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After my recent day of fun at the drag strip, I began to wonder what the optimum shift points are for the FJR. In order to find out, I had to graph rear wheel torque against road speed for each gear and see where intersections occurred.

Results

The MS Excel spreadsheet I created to generate the graphs can be found here. The resulting graphs are displayed below for your convenience. Unfortunately, this forum will not display BMP images, so I had to convert to another format that introduced some artifacts that make the first graph a little more difficult to read than it should be.

fjr_tq_vs_speed.gif


Where one gear's torque curve intersects the next gear's curve, look down to the corresponding speed. Then use the next graph to find out what the engine RPMs would be at that speed in the initial gear. The tachometer is probably more accurate than the bike's speedometer, so it would be better to time your shifts based on RPMs rather than speed.

fjr_speed_vs_rpm.gif


Caveats

  • Speeds are not valid for a GenI bike because of the change in gearing for GenII bikes, however, any resulting RPM-based shift points from these graphs should be applicable to a GenI bike. GenI results could be easily had by modifying the "final drive ratio" value in the spreadsheet (I had to multiply primary and secondary ratio values from my manual to get this value).
  • This is only valid for a bike without any performance mods. If your bike is modded, you would need to calculate everything based on your actual engine torque.
  • The inefficiencies of the drivetrain were ignored, although incorporating it into the calculations would simply adjust all torque values by some fixed ratio which would result in intersections still occurring at the same speeds. For the purpose of determining shift points, absolute torque values are not important.

Sources of Data

Engine Torque: https://fjr1300.info/chart.html. I obtained torque values at 500rpm increments from the graph from 2500rmp up to redline at 9000rpm.

Gear Ratios: Owner's Manual for a 2007 FJR.

Rear Wheel Circumference: Some website I found through google that displays all kinds of tire dimensions based on a specified tire size code.

Methods of Calculation

Rear Wheel Torque (for a given engine RPM and gear): [Engine torque]x[gear ratio]

Speed (for a given engine RPM and gear): ([Engine RPM]/[gear ratio])x[Wheel circumference]x[miles per inch]x[minutes per hour]

(note: gear ratios include the "final drive" reduction ratio which is composed of a "primary" and "secondary" reduction ratio from the owner's manual)

 
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As a guy that has published some mathematics in his lifetime, every publisher will tell you that for every formula and graph you include you loose 1000 readers. Through in the word caveat and this post is doomed! :lol:

 
As a guy that has published some mathematics in his lifetime, every publisher will tell you that for every formula and graph you include you loose 1000 readers. Through in the word caveat and this post is doomed! :lol:
So should I cut out all the words and just leave the pretty pictures? I figured that if I posted results without any explanation of how I got there, people would be asking for explanation. Oh well; I'm proud of my extreme moment of geekiness that gave birth to the graphs :)

 
Thanks for the information and work behind it...glad you had fun at the drag strip.

And I know this doesn't apply to your drag strip analysis...

but in the mean time, I'll just "whale on that throttle" until it "feels right" to shift....scanning the cars I'm passing and the curves ahead...not the tachometer.

'Course I would get "thunped" at the drag strip I'm sure. :)

 
MAN..!!! That's some NEAT shit... I like it lot's better than mine...!!!!

I was gonna do that but all the math and stuff just seemed like too much work so me and my buddy just did some tests and worked out the one below... Seems to work pretty good..

shiftmap.jpg


 
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MAN..!!! That's some NEAT shit... I like it lot's better than mine...!!!!
I was gonna do that but all the math and stuff just seemed like too much work so me and my buddy just did some tests and worked out the one below... Seems to work pretty good..

shiftmap.jpg

:rofl:

Hey, I like this n00b! Finally, one with a funny bone! :good:

 
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Man-O-Man

nice job on the graphs and stuff. Torque/road speed intersection ...hmmmm i guess that is how the smart people firgure out when to shift.

Me? I figure the rev-limiter is how you know when to shift ...that's what I do.

Don't let these guys give you any shit. Especially when funny is often void in such threads. (yep e-berry that is some funny stuff)

Who wants to see a real-life race between

++the torque/road speed intersection math guru and

++the "Twist the dial hard, shift about here ...repeat" graph guru.

count me in as a wagering spectator for that event.

 
Who wants to see a real-life race between
++the torque/road speed intersection math guru and



++the "Twist the dial hard, shift about here ...repeat" graph guru.
 

 


Pickles would kick my ass... I read his strip times the day he posted them. Very respectable.


 


Nope... I'll just sit back here and be a smart ass... (The only thing I do fast anymore is quitin'...)


 
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Interesting. Thanks for posting that.

Now if I could only get my eyeballs to focus on those gauges when it really counts...

 
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