Shifting is easy, right?
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Thread: Shifting is easy, right?

  1. #1
    Registered User Array savagebovine's Avatar
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    Shifting is easy, right?

    Alright, this is a bit more of a racing question, but I'm sure most of you will find it applicable too . I've got two charts here, one for HP and one for Torque. On them I've drawn blue lines for the R6 curves indicating which section of power I would think should be used for maximum acceleration, and therefore where you should shift. Take into consideration that I didn't bother to work in an actual gear ratio for any specific gear change, just a hypothetical situation.

    My question is, which is right? Do you shift at redline which seems to follow the hp curve, or do you shift at about 14k, which would make more sense looking at the torque curve? Or, do you look at it completely different?

    I have some personal thoughts on this already, but I'd like to hear some discussion first.



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  3. #2
    Moderator Array TeeTee's Avatar
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    Actually you want to use from 11,000 to 11,500 where the torque peak occurs (first blue mark on lower graph) up to just to the left of the second mark on the first chart at around the 15,000 rpm point. This range of RPM will give you the best pull and ensure you stay on the best power range.

    There's two charts but they are measuring the same range of RPMs so you need to look at both at the same time.
    A backyard mechanic without a service manual is just like a hooker without a lamp pole.... they are both in the dark.

  4. #3
    Registered User Array Tengu's Avatar
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    I try to keep my RR around 11000 RPM, can't imagine waiting until 13-14 to shift. . . . especially on the street.
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  5. #4
    King AK
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    but is that hard accel or just normal?

  6. #5
    ssblade
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    mag's have done this and explained this before.

  7. #6
    ninja machinist Array Darkcbr's Avatar
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    You'll want to shift at redline to put the revs as far along on the power curve as possible in the next gear. The torque graph means nothing here. The transmission's purpose is to attain the most mechanical advantage. The torque number means nothing because the transmission changes the torque all the time. Just think of how much more torque there is in first gear than second gear. Also, torque is a measurement of force. Power is a measurement of force over time. Don't listen to all the quack wannabe physicists who say the max torque and the torque graph determine performance. Sure the torque curve is usefull information. It can tell you how peaky the motor is. But it won't tell you how fast the bike is.

  8. #7
    Beer League Racer/Asshole Array SnoDragon's Avatar
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    Bruce is right. Keep the bike between 11 and 15 to be in the upper powerband at all times. Good luck keeping the bike at 11k in turn 3 though! If you do, and you don't highside coming out of it, teach me!
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  9. #8
    Registered User Array savagebovine's Avatar
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    Quote Originally Posted by Darkcbr View Post
    You'll want to shift at redline to put the revs as far along on the power curve as possible in the next gear. The torque graph means nothing here. The transmission's purpose is to attain the most mechanical advantage. The torque number means nothing because the transmission changes the torque all the time. Just think of how much more torque there is in first gear than second gear. Also, torque is a measurement of force. Power is a measurement of force over time. Don't listen to all the quack wannabe physicists who say the max torque and the torque graph determine performance. Sure the torque curve is usefull information. It can tell you how peaky the motor is. But it won't tell you how fast the bike is.
    This is exactly what I figured. Anybody, got a rebuttal.

    I've heard so many people talk about shifting at all sorts of different places.

  10. #9
    busa_tom Array busa_tom's Avatar
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    I don't ride the same bike, but on my Busa, I can get going pretty fast. Busa’s reline at 10,800 RPM

    I shift from
    1st to 2nd at around 9000 rpm (Front end about 6" off the ground),
    2nd to 3rd at 10 grand (Front about 6" off the ground),
    3rd to 4th at 10,500. (shift light)
    4th to 5th at 10,500 (shift light)
    5th to 6th at 10,800 Red line

    This is the fastest 9/10ths mile on my bike. My problem is keeping the front end close to the ground in the lower gears but still keeping in the power band.

    These are the speeds I am traveling at these shift points:
    1st gear 130 Kph
    2nd gear 185 Kph
    3rd gear 230 Kph
    4th gear 275 Kph
    5th gear 305 Kph

    First to Second is based on WOT until the bike leaps off the ground and is dependant on the track, elevation and how if I can get my chest weight completely on my tank about 10 feet into the launch. 2nd is barely touching the ground and needs to shift a bit early as well to keep from looping it.

    So from my past experiences I would add that each bike/rider combo is different, as is every track on any give hour based on condition, humidity, elevation. Torque and HP are for magazines, go out and test your equipment and style of riding and find out what works best for you.

  11. #10
    Moderator Array TeeTee's Avatar
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    Actually he's right. In this case shift at 15 and it'll likely only drop to 13 or so so you're on the power peak. Good catch Dark, you got me on that one.

    Not ALL bikes work this way however. My old Ducati 900SS had an early power peak and dropped off the power a lot before reline was hit. On THAT bike you shifted about 1000 rpm before redline so you came out on the other side of the curve at the same power setting and then ride over the hump again for the most average power. But this is sort of a special case. Most of todays engines (and definetly all the I4's) make their peak power up near redline.

    However most will agree that the arm pulling starts at around the torque peak with a really noticable power build up to near peak at around 13K from there and the peak holds over the top to around 15,500 in this case.
    Last edited by TeeTee; 09-25-2006 at 07:29 PM.
    A backyard mechanic without a service manual is just like a hooker without a lamp pole.... they are both in the dark.

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