Would Aero mods be worthwhile on a 49cc?

[Crono]

I have a 2007 Yamaha C3 and have been getting around 95mpg with it, and I think I can do much better than that. (The Yamaha website boasts that you can get 115mpg, but in the fine print it says that's at about 25mph, which I don't find to be practical)

I noticed someone mention installing a windshield can increase aerodynamics, and as I've been thinking about what sorts of mods I might be able to do to my scooter to achieve better mileage, I have been considering/wondering whether, at a top speed of 38mph, aeromods would make much of a difference for me?

I have noted that, at wide open throttle*, tucking in as opposed to sitting normally in my scooter will up my top end by 1-1.5mph, so it seems there must be some difference, at least. Having heard a little about aerodynamics, I can only guess that the form of a rider sitting straight up on a scooter, as one does, can't be very aerodynamic.

*Note that my scooter has an RPM restrictor, so wide open throttle can sort of effectively end up being more like 2/3-3/4 open throttle.

[igo]

Worthwhile? YES!

I am no scooter expert, but if there is a way you can get in a good tuck it will help your mpg/top speed.

[MetroMPG]

Aero mods will help at low speeds precisely because the drag is really bad to begin with. If you have some figures on your scooter (frontal area, Cd with rider), you can plug them in here and see what kinds of gains can be made by reducing Cd:

Resistance calculator: aerodynamic and rolling resistance - MetroMPG.com

Of course you've seen the Craig Vetter scooter aeromod thread?

[Ryland]

because you can notice a change in the top speed if you tuck in, aero mods should show an improvement right away with a change in your top speed as well, same with any other improvements, like synthetic fluids, silica rubber tires, it will all add up.

[dann_04]

Wind definately affects your mpg and top speed. With a headwind my top speed may only be 41mph, but with a slight tail wind it will be 48 mph. That's like a 17% increase in top speed when a headwind isn't an issue, so i would definately say yes aeromods will help. Also losing weight will help alot. My gf can get her 49cc honda to 42mph, i can't get over 38mph but i weigh about 60-70 pounds more than her.

[aerohead]

Tucking in does not reduce your Cd,but it significantly reduces frontal area.If you want to plug some numbers into MetroMPG's formula,you can use Cd0.90,and Af 6.0 square feet( or metric equivalents[I haven't looked at the program sorry!]).I think you'll be surprised at drag at 38-mph.

[dcb]

Originally Posted by aerohead

Tucking in does not reduce your Cd,

Well, it probably does affect CD since you are changing the "shape" of the bike to some degree. You are changing the AOA of your upper torso.

[Matt Herring]

Hey Crono,

I picked up a scooter in June and have also been trying to find a happy medium with tuck, throttle, aero, etc. Getting used to not having the throttle at full blast the entire ride is tough to do when cars are barking up your backside (especially on hills)! Getting better at it though...

I've had mine up to 45mph on a downhill with throttle but because the engine restrictor is so heavy on the scooter I've found flat ground coasting is nearly impossible for lengthy distances.

I think a lightweight, aero deflector shield would have a great positive effect for you. Especially since even a 1-3% increase in mpg from the mod is really magnified 6-10% vs. your everyday car since the scooter is getting 90+mpg vs. your 45 mpg car. My trip to work today on the scooter was windy (mostly in my face) so I could tell my mph was being greatly affected. An aero shield from the front wheel to above the handlebars would have come in handy today!

[Crono]

MetroMPG - I have not actually seen the Craig Vetter thread you're referring, at least I don't think I have. (I've seen a few things about him though, he managed to get a functional 400+mpg out of a motorcycle, or something like that, right?) If you have a link to that I'd be interested in reading up a bit. From the basic specs of my scooter I haven't seen anything about drag, though the point you make about initial resistance being greater makes sense, given that I learned in physics that friction against the ground is also greater from a dead stop. (It's sort of that "initial" friction you need to overcome in order to get something moving, so it makes sense that it works that way with the air as well)

Ryland/dann_04 - Part of what I'm wondering is whether aeromodding will be worth it, depending on the amount of weight gained from an aeromod, like, if I totally went hardcore and went straight for pure teardrop shape, would the weight gained in materials be justified in terms of the loss of drag? I realize there's probably no easy way to tell, but that's generally the line of thought I'm following.

Matt Herring - Especially around here, the posted maximum speed is more like a minimum, so I do tend to ride the thing close to its max. I'll consider that windshield idea, though I'm wondering how much various places would like to gouge me for one. (Being in Canada I'm a little more restricted on what's practical to order online as well, due to duty and shipping stuff.)

[Bicycle Bob]

Do look up Craig Vetter's stuff, but be aware that light, streamlined shapes can get blown around in a crosswind. A simple front fairing that you can tuck in behind won't generate much side force. If you adopt a single riding position, you can add a tail box to increase streamlining and luggage capacity. Light construction is important, but effective shapes will always be worth any reasonable weight.

[ac7ss]

Playing with the calculator you will notice that the mileage will drop almost by half going from 30 to 40 mph. Aerodynamics matter more (geometrically) with speed. I recently changed my cycle habits to drop down to the speed limit and the first tank gave me an 18% improvement in mpg. (45mpg vs 38mpg) Tests are still underway.

I am considering a mod to add a flexible covering (fabric) from my fairing over my legs to the back of the bike. I feel that this will help lower the total CD. Anybody try this before?

[groar]

Originally Posted by Crono

I have noted that, at wide open throttle*[...]

*Note that my scooter has an RPM restrictor, so wide open throttle can sort of effectively end up being more like 2/3-3/4 open throttle.

IMHO, RPM restrictor is a throttle restrictor only when you are at maximal allowed RPM. While accelerating, full throttle is only wasting gas. To save gas don't use full throttle when accelerating.

Denis.

[dann_04]

[quote=Crono;57285]

Ryland/dann_04 - Part of what I'm wondering is whether aeromodding will be worth it, depending on the amount of weight gained from an aeromod, like, if I totally went hardcore and went straight for pure teardrop shape, would the weight gained in materials be justified in terms of the loss of drag? I realize there's probably no easy way to tell, but that's generally the line of thought I'm following.
QUOTE]

I weigh about 60-70lbs more than my gf(who knows lol) and on her 50cc 4 stroke she can do 42, i can do 38. You also have to factor in that i am 6 inches taller than her and have about 3 inches more of shoulder so i am like a big parachute compared to her. so i think that just as long as you don't add over 50lbs you should be fine.

[Crono]

Maybe I might try something like a windshield first, or maybe some ghetto cardboard mods. I've heard that the cardboard doesn't necessarily work that well, though.

[MetroMPG]

It's not the material - it's the design that counts.

If you can taper the rear, that's where to start.