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post #1 of 39 (permalink) Old 06-04-2010, 10:09 AM Thread Starter
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Most aerodynamic front fender

Hey all,

In my MPG quest, I've been working on various aspects of the 250R, including aerodynamics.

I made the mistake of asking the question the same as this thread title in the Two Wheeled Discussion forum. Apparently everyone who had no idea how aerodynamics work, or otherwise had no useful opinion on a simple question, decided to respond to that thread with something stupid. I finally gave up.

The question was just what looked like the most aerodynamic front fender, because I was looking for one for my 250R.

I'm bringing up the thread here because this is specifically about the 250R ('08+, since mine's an '09).

Step 1: I'm going to purchase four used front fenders off eBay.
A) 2007 ZX14R - on order
B) 2003 ZX636 - on order
C) 2002-2005 ZZR1200 - looking around for one
D) ??? Maybe older ZX6E? Still taking suggestions

Step 2: Take pictures of each fender on a high-contrast background- top, front, and side- so they can be put to scale (a ruler in the picture will ensure scale) in a paint program and matched up to determine which one appears to have the most side coverage, frontal coverage, overall degrees of coverage, and most aerodynamic shape

Step 3: make brackets for each one, fit them up, and run with them for at least 2 tanks, and measure MPG. Since I use the bike for commuting, my MPG doesn't generally change unless there's an extreme weather change or a traffic issue, so if one fender is better than the other, there should be a measureable difference.

So, why does this matter?
If you don't already know, wind resistance is not a linear thing. Going 120 miles per hour isn't TWICE as much force against you as going 60 mph. It's actually squared! Anything you can do to make the bike more aerodynamic won't just improve fuel economy. It will also improve accelleration at highway speed, as well as top speed. I'm not going to make some goofy-looking full wheel cover or anything like that. I want to keep a general sport-bike look, which is why I'm looking at other models' production pieces rather than just removing mine and slapping some fiberglass on it or something. Also, using an OEM fender means anyone can make their bike faster and more economical for cheap, since decent used fenders off almost any sport bike can be had for well under $100.

I'm looking for suggestions on another fender to get in addition to the three I have specified above. I will also consider other makes (such as the Hayabusa). A black fender on a black bike isn't all that visible anyway.

I'll post up my findings once I start measuring and testing.

-Travis & Kim
Deyeme Racing
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post #2 of 39 (permalink) Old 06-04-2010, 03:00 PM
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I'm not sure about bike, but I know on cars, the most efficient place to work on aerodynamics is the rear of the car. The car creates a low pressure zone behind it, which in essence, pulls the cars backwards slightly. That's why almost all special high mileage vehicles have long tails. The rear of a vehicle has the largest effect on aerodynamics.

Now I'm not sure if the same applies to a bike since a bike is fairly narrow and doesn't create much of a void behind it. The largest part creating an air pocket behind the bike would most likely be the rider. You'll probably see a greater mpg increase by adding a weird looking tail to your helmet then changing the front fender.

I know you're not looking to change the look of the bike, just some information I knew about.
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post #3 of 39 (permalink) Old 06-04-2010, 03:06 PM
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Shouldnt you be removing all unnecessary weight as well?

05 636 * K&N Air * SS Goodridge frt T-lines * Arata Rearsets * PCIII * Akro Slipon-micron headers* GPR V1 Damper * Michelin Pilot Ones* Elka Triple shock *Nissin calipers* Ohlins 20 mm forks* Keyless entry* what Bikes are about
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post #4 of 39 (permalink) Old 06-04-2010, 06:09 PM
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2000 ZX12 r
This is a photo of Dans Landspeed bike. Looks good and the bike went fast so I think it should cut drag.
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post #5 of 39 (permalink) Old 06-04-2010, 06:28 PM Thread Starter
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Quote:
Originally Posted by bRiT636 View Post
Shouldnt you be removing all unnecessary weight as well?
That's a whole different thing, but yes, we'll be looking at places to reduce weight as well. Weight will affect accelleration, but has very little effect on steady speed MPG or top speed.

I see I put 2002-2005 ZZR1200... if there's a difference between that one and the 2000 ZX12, I'll either get both, or decide between one or the other.

My ZX14 fender came in today, so I'll start working on fabricating brackets for it this weekend.

Just for kicks, I'll make brackets for the Eliminator for it, too, if it'll physically fit between the forks.

-Travis & Kim
Deyeme Racing

Last edited by Deyeme; 06-04-2010 at 06:32 PM.
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post #6 of 39 (permalink) Old 06-05-2010, 01:20 AM
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the indies are using gsxr fenders

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post #7 of 39 (permalink) Old 06-05-2010, 06:07 AM
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You cant put Suzuki parts on a Kawasaki .:-)

Since you are not bound by rules and regulations . You need to get a LSR fender. Covering the open spaces will allow air to move smoothly over the wheel.

I am going to assume you know who Craig Vetter is. If you don't you should study is work.

http://www.craigvetter.com/
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post #8 of 39 (permalink) Old 06-05-2010, 11:21 PM Thread Starter
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Quote:
Originally Posted by biketoczzr View Post
You cant put Suzuki parts on a Kawasaki .:-)
Black fender on a black bike? You'd never know...

Quote:
Since you are not bound by rules and regulations . You need to get a LSR fender. Covering the open spaces will allow air to move smoothly over the wheel.

I am going to assume you know who Craig Vetter is. If you don't you should study is work.

Craig Vetter, designer and inventor of the Windjammer fairing,Triumph Hurricane Motorcycle and fuel economy motorcycles
Yes, I am familiar. I actually don't want to do anything quite that radical, which is why I wanted to try different fenders from actual sport bikes.

The ZX14 fender looks promising. I also got #2 on the list, and it's actually a lot shorter coverage than it appears in pictures- very disappointing. Fork coverage is good, and it's probably SLIGHTLY more aerodynamic than the '09 250R fender, since it doesn't have that stylish cut-back on the sides. Out of the two, though, the '14 fender would be a definate advantage.

-Travis & Kim
Deyeme Racing
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post #9 of 39 (permalink) Old 06-06-2010, 07:03 AM
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I could not see any difference between a 2000 zx12 and an 03 zzr1200 fender. But the 03 and newer zx12 has gone fashion.So it is has less coverage.

AKA Racer X
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post #10 of 39 (permalink) Old 06-07-2010, 11:26 AM Thread Starter
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Got the front mounting brackets made for the ZX14 fender.

Found my ZZR12 fender, and it's on order. The ZX6R fender (the other one I've ordered which has come in) is, by far, inferior in coverage. It has fork coverage, but no better than the OEM 250R fender. That one's definately more style than substance.

I'm going to stick with the three I've ordered. I can't find anything that looks more aerodynamic than the 14s and 12s fenders, except maybe an earlier Hayabusa one. And even that would probably be very little (if any) better than those two.

Once I get the ZZR12 and the ZX14 fender hardware created so they can be attached and detached at will, I'll test them both for at least 400 miles (with my daily commute, that won't take long). I expect both to produce a measurable improvement in highway MPG over the stock piece, but the difference between them to be negligible (that opinion is subject to change once I see both new fenders together).

edit:
rear attachment done for the ZX14 fender. I didn't want to modify the fender at all, but what I did (drill a hole and press in a rivet nut) was a little easier than making a bracket. It's also lighter than using a bracket would have been. If I did this for someone else's bike, I'd probably go ahead and make a bracket to do what I did here.
Also got one of the p-clips fashioned. The wire holders for the speedo and brake are welded on to the 250's fender support, so I can't reuse them. Instead, I'm using aluminum rubber-cushioned p-clips (the speedo one reshaped to be elongated like the OEM holder to allow some movement when steering).

First pics are up. Picture of p-clip turned out badly, so I'll get more tonight when I finish up, and maybe wash and wax the fender.

front attaching brackets - 1/8" thick aluminum, with aluminum rivet nuts.



side view of same front mounting brackets.



ZX14 fender installed with front mounting brackets, before making p-clips (will attach to silver clip nuts on both sides of fender) and attaching at rear of fender (will use rear fork tab, visible in this picture)


front fork tab remains unused. I could trim some material from inside the front fender and use the upper front tab on the fork, but that would weaken the fender. The way it is right now, it's sturdy enough not to need a metal brace. It's a very tight fit, so attaching at two points on each side should be sufficient. I'm curious to see how Dan's ZX12r fender attaches.

Also, for a little LOL (and because they were easy to remove and replace without tools) I used the reflector bolts while fitting up the fender. With the reflectors in place, it makes it look even more like it "belongs" there. They're even close to the stock position!


-Travis & Kim
Deyeme Racing

Last edited by Deyeme; 06-08-2010 at 09:05 AM.
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