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Tire/rim aerodynamics & Silicone II(18 posts)

Tire/rim aerodynamics & Silicone IIWoof the dog
Dec 26, 2002 6:59 AM
do you think it is viable to fill in the gap between the tire and the rim with Silicone II filler stuff they sell in the hardwear store? That should make the whole thing a little bit more aero. That stuff is the shit for a lot of different things too.

Tell me what yall think

Woof the dog.
Dec 26, 2002 9:44 AM
I read in one of my bike books about doing that. Heck, you might save a whole .001 of a second in a 10 mile TT!

re: Tire/rim aerodynamics & Silicone IIMike-Wisc
Dec 26, 2002 12:55 PM
If your question is serious then any time you gain in resistance will be lost in tire changes and weight. Better to go with bladed spokes or deep rims and a proper tire profile chosen for aerodynamics instead of size.

If your question is not quite so serious then yes, go for it, and also streamline everything else on your body and bike for the ultimate aero-MichelinMan smoothness. ;) Remember, every wrinkle in your jersey ultimately costs you time, as does all those air vents on your helmet.
re: Tire/rim aerodynamics & Silicone IIWoof the dog
Dec 26, 2002 7:08 PM
I was serious, and weight gain shouldn't be much. Going to bladed spokes or deeper rim profile will increase weight. It seems that your mentality on the subject is the one of "no aerobars or aero helmets, only downtube shifters" type of stuff (I overexhagurate of course). The leading edge of the wheel makes all the difference, and I have heard that spokes do not matter much if a rim is as deep as a 404 zipp rim. So why not fill in the gap with some silicone and be sure that you did everything possible to be aero. There are full-arm skinsuits and shoe covers, and those do not rotate at twice the speed you are going, like some portions of your wheels. There are aero helmets, etc. These were made for a reason (other than making money).

See where i am coming from?

Woof the dog.

P.S. Doug, i've thougth about it myself, but I probably heard about it before somewhere, and now unconsiously recalled it when started messing with making my own disk wheels.
re: Tire/rim aerodynamics & Silicone IIMike-Wisc
Dec 30, 2002 10:41 AM
I do see where you're going, and I also own a set of aero bars that are mounted on one of my roadbikes. Food for thought: I read in some wind tunnel tests that in some cases a 23 tire width is sometimes more aerodynamic than a 19 width tire.

Are you time trialing or just looking for another edge in the overall picture? Just curious, don't matter, I see nothing really wrong with getting into the fine and nitty gritty details for those times when you want to.

Oh well, another 30 minutes and I'm gone for the weekend.
WAYYY to much time on you handsstr8dum1
Dec 27, 2002 5:22 PM
With all the time you WASTE pondering stupid a$$ questions (2x vs 3x, silicon to fill gaps) you could be training or even working to buy a power meter. Something that will be guaranteed to help you go faster. Do you consistently lose TTs by less than 1/2 sec?

And with such a trvial thing, why not just do it and THEN report back to the group with amazing findings that it increases your avg speed by like 1/2 to 2 mph (just like people say going to Ksyeriums does)
Hey, you don't talk to me like that!Woof the dog
Dec 28, 2002 5:01 PM
I AM training and working. Whats with the negativity I sense?

Cycling is a great obsession and this board exists to allow ANY and ALL questions to be asked.

So shut the f*ck up before me and my buds take you down on one of your rides. I know where you live, so watch your back.
LAUGHING- come on woof, you'd get shelled on my group ridestr8dum1
Dec 28, 2002 6:54 PM
I hope you know where i live. I hope you come out to my group rides. I really do. Ohh please!! Maybe you can teach me to ride a bike to. And then with your siliconed wheels maybe you can drop me in a 20k TT. Better yet, what was your time and placing at National Crit, RR, and TT? They musta been better than mine. Huh, you werent there? You arent a cat 1? Must not be thinking that siliconing your tyres will make you faster.
And you got me pegged. I have no teammates or friends, or hell no respect in the SE racing scene (if you know where I live then I'm sure you know who I am b/c i'm pretty known in the SE.)
You are a funny guy! and i did answer your question, so HA.
SERENITY NOWWoof the dog
Dec 28, 2002 10:21 PM
You didn't get it! To be honest, I expected a lot better from you. Whats up with these 'you have way too much time on my hands' or 'you aren't cat 1' or 'you need to get a job.' You push people away with such comments. Relax and try not to be so full of yourself for participating at Nationals. Your whole 'i am faster than you' issue is lost on me. I do race sometimes but for me this is not the point. Tinkerin' with my bikes and asking questions you may think are stupid is my bag and so is the bag for a lot of us here on this site. I probably wouldn't silicone my wheels but thanx for the comments anyway.

P.S. I highly recommend laying off the caffeine, taking sedatives. If you have nothing to contribute, don't.
personal threatsstr8dum1
Dec 29, 2002 2:08 PM
Hey Woof. You made the personal threats. Not I. My response was not a personal threat since I am better than that. How many people on your 2x vs 3x thread said that you need to move on with something productive? More than just a few. So your questions are NOT in line with what people are concerned with on this board. But anyhow, have a good new years and I'd still LOVE to have you and your buds come out and try to crash me on my group ride!

You talk big. Lets see i bet more people on here wanna learn to ride faster and go to elite nationals than crash out a fellow rider. Yup you are right on target.
personal threatsVeloflash
Dec 29, 2002 5:57 PM
Mmmmmmmmm .... I don't believe you are both bike riders. You appear more like professional wrestlers from the WWF masquerading as roadies.
i get it now....more mud
Dec 29, 2002 7:33 PM
i always thought the wwf was pretty lame.
But if it as entertaining as reading this stuff i might have to tune in. silcone tires and racing in the SE, pretty funny stuff.....
Come onWoof the dog
Dec 29, 2002 10:36 PM
Don't you see that anything and everything that I say on this site is from a viewpoint of a fictional dog that rides a bike. A personal threat was a joke that me and my dog bro's would ambush you and make you crash. I've been around for a while and I am a harmless dog being, so nothing that I EVER say you should take as a personal threat. NOTHING is ever 100% serious on this message board! EVER! If somebody does sound like they are having a hard time dealing with certain issues, I just laugh!

Happy New Year!

Woof, the dog that will beat your Ashville 20k time trial time.
Pax et Veritas53T
Jan 2, 2003 11:47 AM
First of all, I placed pretty damn well at the National pistol championship, so don't mess with me.

Secondly, Woof, you stated that the leading edge of the tire makes all the difference, in fact the trailing edge of any aerodynamic body makes a significant contribution. Not to mention the fact that on a bicycle wheel, the leading side and the trailing side switch twice every wheel revolution.

Thirdly, GE Si 2 on your tires will not make a MEASURABLE difference, so forget it. Keep thinking though, you might come up with something.
Pax et VeritasWoof the dog
Jan 4, 2003 7:49 PM
oh oh, and I placed pretty well at National chainring biting competition...

so the trailing edge of the wheel is the inner part of the rim, right? Pardon the naive question, i should know this stuff, but i don't.


Woof the dog.
Pax et Veritas53T
Jan 6, 2003 5:45 PM
Let's start at the beginning. A wheel is round. What ever edge you identify will be leading on one side of the wheel and trailing on the other. For example, many rims have a nice pointy low-drag shape on the inside, the side where the spokes get attached. When the air you are riding through passes around the front half of the front wheel, the pointy part is the trailing edge. When the air passes around the back half of the front wheel, the pointy part is now the leading edge. Both halves are not equal, since the front half hits calm air and the rear half hits turbulent air. The calm air causes more drag.

I believe that pointy rims work because they present a well shaped TRAILING edge on the front half of the front wheel, where it matters most.

"I could be wrong, but I doubt it." - C. Barkely
The problem with the diagram....Mike-Wisc
Jan 7, 2003 8:33 AM
... is that it doesn't consider the rotation of the tire and the rotational friction relationship of the rotating mass of the tire/rim/spokes/hub/forks/everythingelse and that of the wind or air mass. In oversimplistic terms it is easy to state a comparison of tire/wheel aerodynamics as though the tire were moving through the wind without rotating. But when you factor in the rotation all sorts of stuff happens on a micro-level. Generally speaking the trailing perimeter of the tire never sees clean air, only the rotationally attacking upper leading edges. Takes multi-colored smoke in a smooth wind tunnel, or an extreamly powerfull computer in a well programmed and well setup disgnostic program to see it. But all in all, as I understand things (which isn't too well, and I'm not overly concerned with understanding it much better), you should focus mainly on the leading edge that sees the clean air and the initial profile. After that it's all a messed-up air-stew, though stuff in the dirty air does need to be considered as well (such as shoe booties).

The net effect, as stated above, is to try to leave as clean of an air trail as possible while breaking through it initially as cleanly and smoothly as possible.

I like itishmael
Dec 29, 2002 9:58 PM
seems like a good question to me...especially when(as you say) there is so much other crap out there to go aero...maybe mr straightdumbone needs to wait for it to come to the store and be sold for big bucks with lances name on it and then he'll think its worth his precious time.