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Need more power

Want a lesson in power and gearing............get that old ten speed bike out of the attic. Next find a light up hill grade. It will quickly show the limits of available power and the compromises in gear selection.
 
The bike with the larger tooth rear sprocket will put more torque on the ground, where the smaller rear sprocket will allow a higher top in speed - just takes a lot longer time and distance to get to top end.

I am big, and so is my wife... The bike just requires a lot better rear seat, else she will make the ride very uncomfortable at any speed......
 
Unlike rolling resistance and friction, aerodynamic drag is non-linear and increases at the square of the velocity. If a vehicle requires 10 hp to move at 50 mph, it would require 100 hp to move at 100 mph. To a first order approximation, drag and HP determines a vehicle's top speed.

Physics, and the trade school application of it (known as engineering), are based on mathematical models of physical phenomena. Need to know, and understand, the math and the formulas.
 
Wy wife wants to ride on back and she is heavy.

I hope with all my heart that your wife doesn't get to read your posts or else you'll be opening tins for dinner for the foreseeable future and you can think twice about any nuptials!

I guess you missed the "Tact & Diplomacy 101" class?
 
I find it interesting that rjarrell first posted his inquiry on 11/28 and has not seen fit to make any comments further yet there has been close to 50 replies so far. We do seem to enjoy talking to ourselves, don't we?

Is rjarrell a troll or perhaps he forgot to pay his internet bill and can't post here?
 
Here's an article for you all to read. Probably written by an engineer as it explains some things:
Motorcycle Aerodynamics | Canada Moto Guide

And the article indicates speed (since we're not really addressing velocity) has a cubic relationship to air pressure. But then uses the words "multiple of 3". So not clear on that one.
Horsepower and speed have the squared relationship (twice the speed, 4 times the power). As a rule of thumb that is.

Because I can't resist picking at a scab:

Speed and velocity: velocity is the speed with a direction, while speed does not have a direction. Speed is a scalar quantity -- it is the magnitude of the velocity. Speed is measured in units of distance divided by time.

Drag, V^2 or V^3?
V^2 force of drag. V^3 power of drag: Why is air resistance roughly proportional to the cube of speed? - Quora

NASA has a tutorial on Drag Coefficient that treats drag as a force: The Drag Coefficient
 
You greatly underestimate the effects of rolling resistance and aerodynamic drag. The motorcycle has a terminal top speed because at that point ALL of the engine's horsepower is used to overcome the mechanical losses (internal heat), rolling resistance and aerodynamic drag, and there is no excess power left to accelerate it. As you speed up between standstill and top speed, more and more power is lost to friction and drag. Air resistance is proportional to velocity squared, if I remember correctly. Twice the speed, four times the drag. Acceleration in top gear vs 1st gear is vastly different due to friction and drag losses.

With an example motorcycle, the engine at WOT and at 6000 RPM puts 50 horsepower to the rear wheel in 1st gear. At WOT and 6000 RPM in 6th gear, it also puts 50 hp to the rear wheel. The gearing change from 1st to 6th that allows the rear wheel to spin faster relative to the engine speed also reduces the rear wheel torque by the same factor, leaving the horsepower number the same. However, in 6th gear, the vehicle is moving faster through the air and over the ground. More power is used to overcome the rolling friction and aerodynamic drag, so the acceleration is less. It's that simple.

If we could find a way to levitate above the ground and ride in a vacuum, yet somehow still propel the vehicle, we wouldn't need to have this friendly, educational discussion. :)

Once we can figure out that travel through a vacuum stuff we strip all the plastic off the motorcycles, no need to even pretend aerodynamics matters even a little.

end up with the motorcycle equivalent of this:

1280px-Apollo15LunarRover.jpg


And no need for a turbo when you can simply adjust the regulator from the air tank feeding the air intake for your boost... plus effectively 15 psi of boost just because there is no atmosphere for the exhaust to push against...

Down side, you need to carry that air tank in order to keep the motor running... plus side, you can strip all of the emissions controls.
 
Can someone here just settle this "battle" once and for all.
Take an NC700 and something else 700cc and then do a drag race to a quarter mile.

Then repeat experiment with the heavy wife sitting behind.
Videos please.
Then we can definitively say whether the NC's legendary torque and power are real and true.

PS: I once rode with some big cc bikes and also with my dear friend and his F800R. They all were quite polite to "wait" for me with my NC700X on straight roads. Now on mountain twisties, it is anyone's game. I could be way ahead of them. But THAT, my friends, is all down to skills, experience and BALLS.
 
Down side, you need to carry that air tank in order to keep the motor running...

Now you have me wondering if it would be possible to modify a traditional RICE (reciprocating internal combustion engine) to accept liquid fuel/liquid oxidizer to build a space-bike. I would expect at that point it would be way more efficient to use a traditional LF/LO rocket engine than to try transmitting the power to the wheels.
Or maybe a gas-turbine... I think I've found a new side-project...
 
Now you have me wondering if it would be possible to modify a traditional RICE (reciprocating internal combustion engine) to accept liquid fuel/liquid oxidizer to build a space-bike. I would expect at that point it would be way more efficient to use a traditional LF/LO rocket engine than to try transmitting the power to the wheels.
Or maybe a gas-turbine... I think I've found a new side-project...

It's a fun little thought experiment.

Don't forget about cooling.
 
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