EOC on motorcycle

[saunders1313]

Apparently my motorcycle is not the greatest to EOC on. Although I still do it quite a bit, it takes the most convenient vehicle to EOC or P&G and makes it very inefficient. It still works, but I find that I can’t coast nearly as far as my wife’s Hyundai Elantra. It probably has a lot to do with the momentum.

[dcb]

Same here, it got better when I upped my PSI. The cars glide farther at higher speeds (say above 10mph) and the bike glides farther at lower speeds (< ~10mph) , Aero has a lot to do with it I'm pretty sure. I also noticed I don't scrub off as much speed on the corners on the bike it seems.

[saunders1313]

Well with a bike you can take turns at a larger radius than a car (not as wide) and so you don't have to kill the speed as much. The aero of a bike is terrible. Although it is good that I can draft at 3 seconds behind almost anyone and feel a difference.

[MechEngVT]

The fact that you can easily feel a difference while drafting means that your aero is awful. The more aero a vehicle is the more extreme draft will be required to detect a perceptible difference.

I think you were initially correct when you mentioned both aero and momentum. I think if you took a look at your CdA/mass ratio it will be the defining factor it how well/how far you can EOC at highway speeds. Higher weight and lower CdA will coast further; higher CdA and lower weight will not coast as far.

Motorcycles have horrific Cd, but low A. Both are rather rider-dependent, as is the running weight. Knowing little about bikes, I'll go with some assumptions that between rider and bike you're looking at 1000 lbs, Cd of .5 and half the area of a car. Your car let's say has a Cd of .35 and a weight of 3000 lbs. Your CdA/mass ratio of the car would be 1.17x*10^-4 (x being your total area of the car) while your motorcycle would be 2.5x*10^-4. Since your bike has the higher CdA/mass ratio it will decelerate more quickly than the car (higher drag per momentum). Even if the bike had only 1/4 the area of the car you are still marginally higher on CdA/mass ratio, which will get even worse with a lighter bike or fewer BigMacs. It's not purely scientific and won't help you calculate your actual deceleration, but it's a good method of determining the trend.

You are correct though that at low speeds the vehicle with less rolling resistance (the bike) should coast better.

[saunders1313]

Well actually bike plus rider is around 800 pounds, but what should be accounted for is the fact that it has a lot more broken surfaces than a car, a car is much smoother and allows the air to move around it easier. I have changed my windshield angle, got 2+mpg, think I'll play with it a little more. Next I want to remove the saddlebags as they aren't used much except to carry my lunch or rain gear, both can be stored behind the windshield. After that the second seat backrest is coming off.

[dichotomous]

I'm at 600lbs bike and me, though a bike has more like a Cd or 1.0 often, if I am fully tucked (sportbike) I can coast a LOT further than if I am not.

I will be building a shell for my bike soon I belive, and will see how that helps

[MetroMPG]

Oooh! That'll be something. Please start a new thread if you do start that project.

[dichotomous]

Originally Posted by MetroMPG

Oooh! That'll be something. Please start a new thread if you do start that project.

will do. I'll be designing it out fully with autocad, then possibly asking trebuchet if he wouldnt mind throwing it in flow works maybe. then I can see about building it. the tough part will be making it fit the bike and ME and a passanger and also hold some gear. specifically I'd like to include a trunk that can hold a helmet easily, and places to stow my jacket and boots and such. also I wanna make sure it will handle airflow through the radiator well, since my bike gets hot. also airflow is essential in the summer to keep ME cool, and in the spring/fall to keep me warm, I want both.

the fun part is if I could build something like this well and have it just bolt right on, there is a HUGE number of my bike out there and its one of the most commonly modified bikes, so I could recoup my tooling money easily

[The Atomic Ass]

I can't P&G PERIOD on my Burgman. Centrifugal clutch and all.

I do EOC, and my clutch drops right at 15mph, whereat I can usually coast on flat ground for perhaps another 50'. On the way home, however, I go down a hill in a 25 zone, so I cut the engine, and coast perhaps .2 miles down hill.

A full-body fairing is a big undertaking for any bike. It was being talked about on the Burgman forums some time ago, but I don't believe anything ever came of it.

The benefits of such a fairing would be enormous, though.