mrriggs
XS650 Junkie
Any time the word "performance" is mentioned, it really needs to be qualified as to what task the bike is expected to perform.
Typically the word performance is associated with "faster" but even that leaves the question of, "Faster where?" A bike that is fast on an 1/8th mile drag strip is not going to be fast at El Mirage. If it's a street bike that will never see the timing clocks at a sanctioned racing event then does it really need to be faster or just "feel" faster?
Do you even consider fast when measuring the performance of a street bike? Performance could just as easily mean it starts easily and gets good gas mileage.
In the recent performance gearing thread I made some charts showing rear wheel torque vs mph to illustrate that "More Power AND Higher Top End" is not possible with gear changes alone.
Charting rear wheel torque vs mph is the best way to determine optimum shift points [if your goal is maximum acceleration]. Since I have all the data for my bike I decided to put together a chart.
Optimum shift points for my bike.
Yes, first gear is poorly matched to the rest. I hope to find a 256 gearbox for my bike to rectify that.
Also note textbook torque dip at 4k from drag pipes. I'm surprised nobody questioned that in the other thread.
Contrary to what the charts suggest, I did not choose this sprocket combo based on maximum standing start acceleration. It was actually to improve low speed "performance" (the improved acceleration was just a bonus).
The highest posted speed on my daily commute is 40 mph. With this gearing I can effortlessly pull away from a stop and short shift around 3500 rpm until settling in at a relaxed 3000 rpm at 40 mph in fifth gear.
When I do get on the freeway it's in town where the speed is 60 mph and [believe it or not] this bike runs smooth at that speed [even in fourth gear].
So, based on where I expect my bike to perform, the low gearing offers the best performance. Relaxing daily commute, good gas mileage, and it "feels" really fast when I crank on it.
So, how do you measure performance of YOUR bike?
Typically the word performance is associated with "faster" but even that leaves the question of, "Faster where?" A bike that is fast on an 1/8th mile drag strip is not going to be fast at El Mirage. If it's a street bike that will never see the timing clocks at a sanctioned racing event then does it really need to be faster or just "feel" faster?
Do you even consider fast when measuring the performance of a street bike? Performance could just as easily mean it starts easily and gets good gas mileage.
In the recent performance gearing thread I made some charts showing rear wheel torque vs mph to illustrate that "More Power AND Higher Top End" is not possible with gear changes alone.
Charting rear wheel torque vs mph is the best way to determine optimum shift points [if your goal is maximum acceleration]. Since I have all the data for my bike I decided to put together a chart.
Optimum shift points for my bike.
Yes, first gear is poorly matched to the rest. I hope to find a 256 gearbox for my bike to rectify that.
Also note textbook torque dip at 4k from drag pipes. I'm surprised nobody questioned that in the other thread.
Contrary to what the charts suggest, I did not choose this sprocket combo based on maximum standing start acceleration. It was actually to improve low speed "performance" (the improved acceleration was just a bonus).
The highest posted speed on my daily commute is 40 mph. With this gearing I can effortlessly pull away from a stop and short shift around 3500 rpm until settling in at a relaxed 3000 rpm at 40 mph in fifth gear.
When I do get on the freeway it's in town where the speed is 60 mph and [believe it or not] this bike runs smooth at that speed [even in fourth gear].
So, based on where I expect my bike to perform, the low gearing offers the best performance. Relaxing daily commute, good gas mileage, and it "feels" really fast when I crank on it.
So, how do you measure performance of YOUR bike?
