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To belatedly go right back to the original post I have to pick you up on this statement:-
The most critical performance observation to note though is that any RPM, including redline, produces more power at the rear wheel in any particular gear than upshifting to a higher gear.

That is simply not true.

You can have as much torque as you like at the back wheel - by changing the gear ratios. This is just like saying that a 10 stone weakling can move the earth - provided he has a long enough lever!

The reason that this won't help you accelerate any faster is because it will only rotate the rear wheel much more slowly.

Regards Roadster
 

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Discussion Starter · #85 ·
To belatedly go right back to the original post I have to pick you up on this statement:-
The most critical performance observation to note though is that any RPM, including redline, produces more power at the rear wheel in any particular gear than upshifting to a higher gear.

That is simply not true.

You can have as much torque as you like at the back wheel - by changing the gear ratios. This is just like saying that a 10 stone weakling can move the earth - provided he has a long enough lever!

The reason that this won't help you accelerate any faster is because it will only rotate the rear wheel much more slowly.

Regards Roadster
I was referring to the context of that chart I posted with it when stating "any" RPM. As far as "a 10 stone weakling can move the earth - provided he has a long enough lever", I am indeed saying that. It's not relevant to this context though because of your last statement "The reason that this won't help you accelerate any faster is because it will only rotate the rear wheel much more slowly." Logically, the engine, or in your example "the 10 stone dude" can't run fast enough for it to translate into anything useful. That'd be like have a really really really low gear ratio that was ungodly strong but red-lined at 3mph. :eek:
 

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Well I changed out my stock drive sprocket today, for the 13T sprocket. Went for a short test ride and... Wow... What a difference one tooth makes! Both 4th and 5th gear feel like they just woke up from a long nap... much stronger acceleration. I didn't have a long enough stretch of road to run it all the way out in 6th, but the shift from 5th into 6th at 9500 RPM seemed seamless, with a less pronounced RPM drop, and the bike continued to accelerate at a respectable rate. Of course this is all just seat of the pants dyno, but at the end of the day, how the bike runs out on the road is what really matters. I'm very pleased with the results. :)

@ Rusty... can you post up the link (or name of the company for the speedo healer)?... Thanks.
 

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Well I changed out my stock drive sprocket today, for the 13T sprocket. Went for a short test ride and... Wow... What a difference one tooth makes! Both 4th and 5th gear feel like they just woke up from a long nap... much stronger acceleration. I didn't have a long enough stretch of road to run it all the way out in 6th, but the shift from 5th into 6th at 9500 RPM seemed seamless, with a less pronounced RPM drop, and the bike continued to accelerate at a respectable rate. Of course this is all just seat of the pants dyno, but at the end of the day, how the bike runs out on the road is what really matters. I'm very pleased with the results. :)
Makes perfect sense at your altitude ( 10+% power loss?). I reckon it equates to about 9 m.p.h. per 1000 rpm in top gear. Probably good for 80-85 m.ph. on level ground ( if you have any!)
 

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-1 front is perfect,
any less is a step backwards, any more and our 23hp cant pull it, (as we all know with std gearing it dies in 6th under loads)

Bikes come high geared from the factory to pass stringent noise and emmission ride-by testing.
Simple fix is -1 front and the bike is the way it should be.
 

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Discussion Starter · #89 ·
@ Rusty... can you post up the link (or name of the company for the speedo healer)?... Thanks.
12 o'clock Labs SpeedoDRD

Simple fix is -1 front and the bike is the way it should be.
I'm a 100% street rider and don't spend much time over 75mph, so -1/+2 is perfect for me, but I don't think anyone would disappointed with -1 in the front. I ran that for over a month, and after comparing it to stock, and now with the extra +2 in the back, I definitely agree that -1F is the way it should've came from the factory.
 

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-1 front is perfect,
any less is a step backwards, any more and our 23hp cant pull it, (as we all know with std gearing it dies in 6th under loads)

Bikes come high geared from the factory to pass stringent noise and emmission ride-by testing.
Simple fix is -1 front and the bike is the way it should be.
Got a 13T for $14 shipped from riders discount...and got the non-oring chain too...gonna try it at barber this weekend for the grand national finals. 2.5 mile track so I should see if terminal velocity increases as it doesn't take much of a straight to be long enough to wind out on these lil bikes surprisingly. Even at Lil Tally which is only 1.5 miles long, I was topped out in a couple places.
 

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Discussion Starter · #97 ·
If you think 6th gear doesn't have enough power with 14/38, I wouldn't go higher. 1st gear doesn't have as noticeable of a change because it's fairly low to begin with. 6th gear is noticeably different after regearing, though.
 

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also i don't get how it affect's the speed o meter
The speedo sensor is electronic, and is located in the transmission. The sensor reads revolutions of the transmission output shaft, and sends this signal to the digital speedometer. If you change the size of one, or both, of the sprockets to affect the final drive ratio, the rear tire will rotate a different rate than what the speedometer is calibrated for. For example, if you were to lower the final drive ratio by changing from the stock 14T front sprocket, to a 13T sprocket, the speedometer will read faster than your actual road speed. For a taller final drive ratio, as you would have using a 15T front sprocket, your speedometer will read slower than your actual road speed. Fortunately, the speedo error can be easily corrected, using an aftermarket device called a SpeedoDRD. I just installed one in my CBR today, and it works great.

For what it's worth, I would not gear this bike taller. It just does not have the power to pull a taller final drive ratio. IMO, taller gearing = performance killer. :(
 

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Simple rule of thumb with gearing is if it cant redline in top gear she's too high,

With the the cbr you are not making advantage of the whole 23hp with stock gearing (unless you weigh 45kg or less).
 

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Depends how much top speed you are willing to trade in order to get the fastest acceleration. Any given bike also depends on how much the power curve is falling away on the top end which is quite a bit on this bike unless you cut down the intake runner and fit a pod filter. It would be interesting to see if anyone could redline Rusty's -1,+2 gearing. I am thinking that even the most aero rider would only hit 89 mph at 10,000 rpm. 13/ 42 gearing might redline 6th with an honest 88 mph. Down a steep hill Rusty's bike could probably pin the rpm at 93mph.
 
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