When is best to change gear?

[Visitor Q]

Following on from this thread and some of the comments made about my video, i was just curious what people felt was the best time to change up?

Below is the print out of my dyno graph
https://www.bikechatforums.com/download.php?id=32500

Which shows peak power being made around 12,250 rpm

https://www.bikechatforums.com/download.php?id=32499

This Shows peak torque is at around 11k rpm

Now in the video, im accused of shortshifting my gear changes, and looking at the video again im changing at just past 11k (so possibly a little bit of room for more revs), but what possible good does revving into the red do?

To me it seems 'burying it into the red' is only really worth doing if you want to achieve a higher top speed, but keeping it in the torque is more for acceleration?

Any feedback on this?
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[bish777]

best time to change up is just past peak torque, that will get you best accelleration. Itll take more time if you hang on for peak power.
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[Visitor Q]

So, in theory, my changes are correct for acceleration?

As (bear in mind that video was taken last summer before i got it dynoed) all my changes seem to be around 11/11.5k in that vid, which is just after peak torque.
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[suzi_bandit]

Oh blimey.
Far too technical in here for me. Besides colouring them in I wouldn't know where to start with those graphs.
I best toddle off in search of a more menial thread to post on.
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[0ddball]

Just before the limiter in most cases. Looking at the torque graph only tells half the story. Don't forget that those torque values are multipled through the gearing before hitting the road.

Often when you work it out the torque value at higher revs in (for example) 2nd gear will be higher than what it would have been had you short shifted into 3rd.

Of course this theory is dependant on the gearing and shape of the torque curve. The only way to be sure is to get the calculator out.

[Visitor Q]

Eh...?

Well ok, ill try and add a poll...

Do you prefer to change gear at peak torque, or just before it rattles off the limiter?
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From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[bish777]

[impaler]

Based on those graphs I'd say the best time to change would be at 11.5-12.0k, that way you'll still be in the peakish torque range in the next gear. But I'm certainly not an expert on such things
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[TheShaggyDA]

I change gear when it feels right, so that when I get into top, the revs drop into the "sweet spot", i.e. where they would be if I were cruising. I do it with cars too. It seems to be somewhere midway between peak torque and peak power, but it varies from vehicle to vehicle, depending on how flat/peaky the curves are.

If I were going for it, I'd change on the redline.
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[Visitor Q]

VICTORY IS MINE!!!!!!!!!!!!!!!!!!!!!!!!!

As a point that vid was taken before dyno, but also before new headers and k + n so its possible the peak torque range has raised slightly.

Anyone watched the video?
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China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[Visitor Q]

Sorry i meant to say when pelting it, obviously if we are behaving down the local residential estate we may be in third at 4k doing 30.

so yes, poll refers only to when shifting.
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From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[dodsi]

max power is between peak torque and peak power.

You change gear at peak power and it should drop back to peak torque.

[EuropeanNC30R...]

[bish777]

ah but sometimes its better to hang onto a gear if your not exactly sure if your gonna have to slow down around that next bend/obstacle/sheep......

race track and drag strip arent the same you know.

Also not so much of an issue on a 200bhp superbike.
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[mistergixer]

When the valves start to bounce.

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[EuropeanNC30R...]

Have you done much drag racing Bish?

[www.125power.com]

Okay i drew two guick graphs to help explain. Graph one is a full dyno run form 1st to last gear the spikes between power curves are obviously gear changes. The black line represents a good change pattern. The red line shows what happens to your power curve when you change too low rpm missing your power peak. The green line shows what happens when you "overshoot" your gear change and only catch the very last bit of maximum available power on the next gear. The blue shows the areas of each gear that your bike will accelerate at its best, its powerband.

Ideal gear changes mean you will never leave the powerband until you are in last gear and have no option but to keep piling up the revs.

Although the above depends on the gearing of the bike

Graph two is a full speed run of each gear all plotted on the same graph e.g 1st 0-50mph 2nd 15mph-70mph etc etc

in graph two you will see as you go up the gears the torque at the rear wheel decreases. The best time to shift is not always at max torque. Shifting at max torque may drop your bike way below its powerband in the next gear making it very sluggish. Also the opposite is true if you get every last rpm before shifting maybe you will snick next gear too high over powerband or only be in it for a little while.

If like you look at graph 2 also every gear will overlap the next and previous with speeds the speeds acheivable in that gear. for example 60 mph could be 10,000rpm in 2nd 7000rpm in 3rd or 4,500rpm in 4th. Depending on where you produce max torque will depend on what gear is best used at this speed.

The idea is to "trace" the outline of highest torque through all gears, keeping the bike at its maximum possible power for the given speed.
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[Visitor Q]

Oooooh... interesting.

Divided camps on this one.
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China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[Dom_]

I tend to change at peak power which i feel is at about 11-12k rpm.

If i'm going for it i change just after the redline, even though i'm making less power, it sounds better and puts you more in the mood.

[G]

For maximum go, you should be changing so that you can be using as much power as possible as much of the time as possible.

Basically, with a fairly symetrical peak power peak, you want it so that you change up past peak power, at the point that it will then drop you to the same amount below peak power in the next gear.

[Visitor Q]

So G, would you mean more about 13k on my bike judging from that graph?
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China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[G]

Around about where the graph ends I would guess, though depends on your internal gearing, obviously.

[Visitor Q]

Ooooh you people are confusing.
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China traffic/travel bike vid - When I make a sweeping statement, please add the word 'statistically' in to the sentence before you bitch...
From September 2014 to January/February 2015 I will not be using any English, nor reading any. As such, I won't be on here. PM at will, but I won't be checking/posting unless in emergencies. Certainly not for the first couple of months. Please berate me savagely if I break that rule...

[Wave2k]

Depends on what type of riding im doing.
My bikes a fun bike so its only to have fun on so usually ill change at about 6-7k which is quite high for a twin.
on a SE rideout i tend to push a little more and change at about 10k which is about max torque for a 749.
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[EuropeanNC30R...]

Meaning by how far your gear ratios are apart, how many revs it drops when you change up.

Victory slowly slipping from your grasp Bonny