HP and cornering

1. ## HP and cornering

Another member and I have been having an ongoing debate for the last little while regarding the effect of horsepower/torque on the cornering ability of a bike.

Basically, he said a gsxr600 will be able to go through a corner faster than a gsxr750.

First off, assume that the bikes are completely identical (in terms of weight/distribution, tires, traction etc), the only difference being the HP/torque they put out at the wheel.

His argument: The 600 is faster because it puts out less torque, allowing you to get back on the throttle earlier/harder than on the 750, and consequently get through the corner faster.

My argument: The 2 bikes should both theoretically be able to negotiate the corner at the same speed. The only drawback on the 750 is that it requires stricter throttle control to avoid wheelspin/slides.

We both agree that the 600 would probably be easier to ride closer to it's limit (for the reason stated above). I just believe that the theoretical limits are the same...

Anyone wanna prove one of us wrong?

2.

3. i have been questiong this myself
i cant get past something
the 600 will have less gyroscopic force from its smaller lighter internals trying to keep it upright, allowing it to turn in faster..
but at the same time it will be reving higher (making more force) to go the same speed, would these equal out to the 750?

4. The one difference is the crankshaft. The 600 has a lighter one. When you get on the gas, everything else being equal, the 750 will want to 'stand up' slightly more than the 600. Therefor, the 600 should be able to accelerate slightly faster, as it won't vear to the outside of the corner as much. Once they're both straight up, it reverses of course, but the 600 should exit a little faster. Depends on the size of the corner really.

5. I'm talking about IDENTICAL bikes. the ONLY diff is the HP/torque put out at the wheels...

The one difference is the crankshaft. The 600 has a lighter one. When you get on the gas, everything else being equal, the 750 will want to 'stand up' slightly more than the 600. Therefor, the 600 should be able to accelerate slightly faster, as it won't vear to the outside of the corner as much. Once they're both straight up, it reverses of course, but the 600 should exit a little faster. Depends on the size of the corner really.
even if this is the case, why not just apply more force on the bars or lean harder to keep the bike leaned over?

6. i think you're missing the point. The point is, if you can read, is that the bikes are inherently different. that means crankshaft, weight, where the weight is concentrated, power, blah blah blah

7. k SMZ, don't go changing the topic now. We made it abundantly clear when we were discussing this that the bikes were identical; HP/torque output/curves being the ONLY difference...

8. Don't forget the gixxer 600 and 750 have different swing arms, the difference in length will affect the wheelbase which in turn might change the geometry of the bike.

Also remember the limitation of the tyres when you are dealing w/ high horsepower.

9. If the bikes are EXACTLY the same except for the power curve, then wouldn't the defining element be the tires? If the 750 can lay down more power than the 600 AND still keep traction, won't it be ahead?

10. You also have to remember the actions of polar moment. This is very critical in the ability of a bike to be turned in a corner. Polar moment is best explained by an example:

Hold a bucket full of water in your hand swing it around. Pretty easy eh?
Now do it again but this time attach the bucket to a long stick. This time it's a lot harder.

The farther you are away from the center of gravity the harder it is to turn it.

This is how bikes work and this what engineers will try to minimize. Your bike has 2 planes where along each plane there is a center of gravity.

1. Length wise (rear tail to front). The center of gravity is not at the wheels but slightly higher. Engineers try to bring the heaviest objects in a bike closer to this center of gravity line. Thus, you want to bring things lower than the line up and things above it down. 600's and 750's have different engine heights etc. Meaning a 750, (with all other things being equal) will not turn as fast as a 600. But if that 750 had been engineered better than say an old 600 from then yes it is possible for it to turn faster.

2. There is also another plane in which things on either side of teh bike will reduce turning and flicking ability. The more narrow the bike the closer everything is to this center of gravity. I'm guessing a 750 would have a slight wider body than a 600 but I guess it depends on the bike

So to answer the question 600's and 750's are not equal for the reasons explained above so you can't say "all things being equal" because they're not. These are physical laws. 750's are bigger bikes and there is nothing to change that. 600's can enter a turn faster than a 750. Watch GP racing and observe the corner speeds of a 125 vs a 990cc MotoGP bike. You can't minimize displacement in an engine.

11. whoops geebutbut, should have read your post more carefully...if all the things I said above were equal (which is impossible) then the HP shouldn't affect cornering speeds as long as the rider is controlling the throttle and knows at what RPM to enter a turn. As long as he is matching the power of his bike to the cornering ability of his tires then entering the turn should be equal for both bikes assuming identical tires and everything else. As soon as the bike passes the apex and stands up the 750 will destroy the 600.

So entering: both the same (hypothetically speaking)
Leaving: 750 is faster

12. "Torque x RPM = HP"
At the rear wheel, you can't have more horsepower and less torque or vice versa. It's a linear relationship that will be identical on both bikes assuming same sized rear tires.

You said the bikes were 100% identical other than the power curve. So then it comes down to whether the 600 is "short" of power. If it can go WOT through part of the corner, we can assume there's room for a bit more power from the 750, which would mean the 750 would be faster. If both bikes can't utilize all their available power, then they'll corner at exactly the same speed assuming a perfect rider.

13. there never gonna be identical so stop arguing, LOL

14. I just wanna prove SMZ wrong

15. I think my bike will be the fastest as it's got a low center of gravity allowing me to lean over farther. And being a 600 I can down shift and rev higher to reach my power band and blast out of the corner at mach stupid!

16. Originally posted by geebutbut
I just wanna prove SMZ wrong
dont worry ive already proved him wrong, my 600 was faster than his 750

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