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mirror drag

Posted: Tue Mar 24, 2009 3:36 am
by gsxrg
Just wondering if mirrors have that much drag. A buddy of mine took off his mirrors and is now able to pass me. (top speed). I used to edge him when he had mirrors. Is there any low drag mirrors?

Posted: Tue Mar 24, 2009 9:50 am
by burnt_toast
yes and yes, especially the elite stock mirrors. they are large and create lots of drag, considering the small profile size as you're riding.

removing mirrors is good for about +3mph at very high speeds

can find smaller mirrors on ebay. I had a pair of JDM low profile ones:

Image

Image

Aero

Posted: Tue Mar 24, 2009 10:10 am
by Wheelman-111
Greetings:

Motorcyclist declared the 1982 Kawasaki GPZ 1100 to be the fastest production bike on the planet in 1982. With its little quarter-fairing and the rider in full tuck, it reached a measured top speed of 141 MPH. Kids, these are trained professionals, don't try this at home!

The testers had the same thought, and so removed the mirrors and remeasured. Now she was good for 144.

Now at three times the speed, there is nine times the wind drag, so a 3-MPH difference isn't a fixed value for expected gains. The much larger frontal profile and the lack of streamlining on the bigger bike, along with enormously greater power to fight the drag, simply added up to 3 in this specific case.

At 40-70MPH down here in Scooterworld, I bet the mirrorless gain is closer to 1 MPH or so, not 3; but I do believe the difference would be enough to notice, as in going from just ahead to just behind. Good thing your friend couldn't see your chagrined face in his mirrors... :)

Posted: Wed Apr 01, 2009 1:40 pm
by Darkness's
That is all true! I never thought about applying it to scooters but drag can happen to anything.

Along the same lines, I wonder what increase you can get from removing the mirrors and taping your seems up, especially the vent on the front panel for the horn and around the headlight, I would think that would act as a parachute since there is no way for the air to leave those cavities...
All the Bonneville cars tape up for a reason.... It works!

I will do some testing once I get everything back together...
What is the best way to get accurate speed readings?

A Need, A Need for Speed

Posted: Wed Apr 01, 2009 4:30 pm
by Wheelman-111
Greetings:

Drag reduction will buy speed, unquestionably. Bonneville cars have indeed discovered the benefits of taping door seams and all.

However the gain/effort ratio is much higher at 255 miles per hour than it is at 55. I'd rather keep my mirrors and see that pickup pulling up behind me at the traffic light... 55.037 just isn't worth it.

Besides, pulling duct tape off my 'stache and eyelids hurts like a bee-yotch. That plus nobody needs to see Wheelman in a Lycra suit. On the other hand, I'm delighfully free of unsightly ear hair lately.

Posted: Wed Apr 01, 2009 6:01 pm
by jesse1234
what size mirrors do we have to get? I want to get some low-profile aftermarket ones

Posted: Wed Apr 01, 2009 6:43 pm
by Darkness's
jesse1234 wrote:what size mirrors do we have to get? I want to get some low-profile aftermarket ones

I picked up some Koso street bike mirrors off ebay, they come with all the different adapters, they fit great and in my opinion look SWEEEEET! Gives my scoot a nice race look LOL

Just my 2 cents...

Posted: Thu Apr 02, 2009 2:29 am
by maddog
the first thing you want is to build an engine that will scare you, glad i have plenty of those, mirrors let me know what idiots i need to pass :lol:

Posted: Thu Apr 02, 2009 8:21 am
by noiseguy
When I was at GM mirror surface design was a big deal... different designs would impact MPG. A good design was .1 MPG hit, a bad one .4 MPG. Guess same applies to scooters.

What's Behind Me Is Not Important

Posted: Thu Apr 02, 2009 5:12 pm
by Wheelman-111
Greetings:

Wow, the Wisdom of the Phorum!

MadDog pens:
mirrors let me know what idiots i need to pass
Uhh, Dawg; If they're in your mirrors, aren't you already out front?

Noiseguy submits:
When I was at GM mirror surface design was a big deal... different designs would impact MPG. A good design was .1 MPG hit, a bad one .4 MPG. Guess same applies to scooters.
I agree to a point. Mirrors on cars are a much smaller percentage of total frontal area than they are on scooters. Furthermore they're in a turbulent area on each side of the windshield, further reducing their impact on top speed and MPG. On trucks with their macho outboards it makes a bigger hit. (Why do trucks need such big ones, anyway. Does the world get larger when you climb up into one? Overcompensation for tiny penises, methinks.)

On the other hand, aerodynamics doesn't play much of a role at all on either top speed or MPG until ya gits ta goin' fast. Stock scooters that run 35-40 won't see much gain by removing or mounting smaller mirrors. At highway speeds - 60+, I could see bigger benefits. 141MPH became 144 on the 1982 GPz-1100, for example.*

Remember wind drag is proportional to velocity Squared.
That means there's four times more drag at 80 than at 40. Sixteen times more at 160.

Posted: Thu Apr 02, 2009 5:21 pm
by jesse1234
There's a little radar speed tracker thing on one of the streets in town. The thing is pretty close to an intersection, so I was able to get up to 35 with mirrors, 36 without! lol

Posted: Thu Apr 02, 2009 8:53 pm
by noiseguy
I actually spent more time on truck mirror design than I'd care to recall... large mirrors are meant for trailers, BTW, regardless of what the customer is actually using it for.

My point is more that it does matter. Frankly, one would probably go faster if one lost weight too, or wore a tight spandex shirt.

Posted: Thu Apr 02, 2009 9:00 pm
by Kenny_McCormic
I always though big mirrors were for backing up large vehicles. I can back up my dads long box 1500 4x4 fine with its mammoth mirrors, I can back up my little camry pretty good with its little mirrors. But I can not back up my mothers caravan, I blame the smallish mirrors+large vehicle.

Posted: Thu Apr 02, 2009 10:20 pm
by burnt_toast
wheelman I have personally gps'd a +3mph gain, stock elite mirror profile ratio to mirror profile of said bike is greater for the elite, and more of an affect.

I did not say it was finite, note I said about anyway.

Posted: Thu Apr 02, 2009 11:55 pm
by devenex
noiseguy wrote:one would probably go faster if one... wore a tight spandex shirt.
Get ready for my first how-to, I have a feeling its going straight into the Advanced Tech Docs ;)