Getting a drag. [Archive] - Kiwi Biker forums

texmo

5th June 2006, 18:49

When following somebody on a straight how close do you have to be to get pulled along? also if I was following somebody on the same bike could I use the drag effect then pull out and pass them.

N4CR

5th June 2006, 18:52

You won't stick with me enough to pass me on the straight if that's what you are meaning :lol:

GET IT TUNED, then yes.

You need to be pretty fuckin close.. 1m-2m or so depending on speed and if they hit the picks... it's not nice. Have slipstreamed a few times on the fxr150.. it's the only bike you can sorta do it on without breaking the law big time.

Colapop

5th June 2006, 19:14

You'd have to be going pretty quick. Those boys in the superbike are hitting some serious k's on the straights. At a guess I'd say something in excess of 200kph to get any effect for the following rider apart from just pushing through the air. Coz aint slipstreaming when you get almost pulled along by the rider in front?

Motoracer

5th June 2006, 19:42

When following somebody on a straight how close do you have to be to get pulled along? also if I was following somebody on the same bike could I use the drag effect then pull out and pass them.

You'd have to be pretty close like N4CR said. And yes you could do it on same bikes but obviously not unless both of you are clocking the top speed of your gear ratio.

Motoracer

5th June 2006, 19:50

aint slipstreaming when you get almost pulled along by the rider in front?

You are basically getting sucked into the vacume of the bike infront of you where there isn't much wind resistance.

I've had this effect even on a van out in the highway when a speeding big bus was going at about 130+ and I got in behind him and was able to noticebly accelerate faster behind him right upto the point where I pulled out and overtook him. The speeds were much lower than the bikes but the bus covers a huge area and they are one of the most unaerodynamic vehicles around. Therefore the pisspoor airflow on the bus created a pretty huge vacume.

Shaun

5th June 2006, 20:02

You are basically getting sucked into the vacume of the bike infront of you where there isn't much wind resistance.

I've had this effect even on a van out in the highway when a speeding big bus was going at about 130+ and I got in behind him and was able to noticebly accelerate faster behind him right upto the point where I pulled out and overtook him. The speeds were much lower than the bikes but the bus covers a huge area and they are one of the most unaerodynamic vehicles around. Therefore the pisspoor airflow on the bus created a pretty huge vacume.

You feeling better now man?

FROSTY

5th June 2006, 20:03

Slipstreaming is very effective if you know how to use it. The secret is its a triangular zone fanning out from the rider in front. You quite literally get a tow off of the bike in front.
Lil secret here -whatever you do dont hit the elbow of the guy you've been slipstreaming for a lap or two he's liable to freak out --AYE KK???

Motoracer

5th June 2006, 20:25

You feeling better now man?

Huh?? Now what's this about? Have I made a dick out of myself without knowing? :confused:

I feel good most of the time man. Got my nice bike, got my job (for the moment), a place to stay at and ma bitches (Loosebruce, texmo, HDTboy etc). A man can't ask for much more. :second:

texmo

5th June 2006, 20:27

Huh?? Now what's this about? Have I made a dick out of myself without knowing? :confused:

I feel good most of the time man. Got my nice bike, got my job (for the moment), a place to stay at and ma bitches (Loosebruce, texmo, HDTboy etc). A man can't ask for much more. :second:
good looks might be a start.

Motoracer

5th June 2006, 20:42

good looks might be a start.

Bro that's it! You and me, we'll have a good ol fashion show down... Put some money into it as well. Who can get the most phone numbers of some rather hot females. Thoes drunk blind bats at the club might have liked you better cause of your sexy manly musceles but come out during the daylight and I'll put my charm into action. You don't stand a chance!

N4CR

5th June 2006, 20:46

Thoes drunk blind bats at the club might have liked you better cause of your sexy manly musceles but come out during the daylight and I'll put my charm into action.

More like 'ooh look a guy with drinks and a bit of baggage lying around'. Let's take advantage of him and steal from him!
:blah:

But yeah that would be a rather funny competition.

sAsLEX

5th June 2006, 20:48

Try behind big trucks on the MW when its clear, little chance of them randomly braking but keep your wits up though

texmo

5th June 2006, 20:55

Bro that's it! You and me, we'll have a good ol fashion show down... Put some money into it as well. Who can get the most phone numbers of some rather hot females. Thoes drunk blind bats at the club might have liked you better cause of your sexy manly musceles but come out during the daylight and I'll put my charm into action. You don't stand a chance!
I would like to come back with a snazzy reply but I cant rember much of the night other than giving a chick a drink before going for a spew, I made the misstake of have some chartruse green afterwards as well... but ok name a time and place dude and ugly chicks dont count.

Motoracer

5th June 2006, 21:01

I would like to come back with a snazzy reply but I cant rember much of the night other than giving a chick a drink before going for a spew, I made the misstake of have some chartruse green afterwards as well... but ok name a time and place dude and ugly chicks dont count.

Mission bay next Sunday, if the weather is as beautiful as it was today. Time? How about just past midday.

Who wants to be the judge?

Prize? Fuel money for a whole ride for the next organised ride.

Are you game?

texmo

5th June 2006, 21:12

Mission bay next Sunday, if the weather is as beautiful as it was today. Time? How about just past midday.

Who wants to be the judge?

Prize? Fuel money for a whole ride for the next organised ride.

Are you game?
how about the 1st or second as im gonna be in manfeild next sunday and the sunday after. Fuel money for the next ride sounds ok, I will arrange a ride to mangwhai heads.

vtec

10th June 2006, 12:37

I reckon that once you are over about 120k/hr the effects on a less powerful bike such as a streetstock machine are probably more noticeable than say on an F2 machine. It definitely helped me on Pukekohe chasing F3 bikes, with drafting very closely I managed to stay with noticeably more powerful machines up until I hit revlimiter in 6th with the standard sprockets. Due to drafting, I got the bike up to it's max speed in a very short space of time, half way down the back straight at Puke. Without drafting, I probably only got to the limit once. Drafting definitely has a huge impact on lesser powered bikes. Also would have a really good impact on more powerful bikes at higher speeds too.

Here's a pic of what's happening, it's the best I could do in paint.

texmo

10th June 2006, 12:58

nice vtec chur for that. I still havent heard back from vic club so im starting to sweat.

vtec

10th June 2006, 13:21

Hmm, don't let it get to you tex. But if you are really worried, you could just give someone a call. Or get in touch with whoever it was that is helping you out from VMCC

Also for those skeptical about the benefits of drafting, you should seriously try doing a cycling race to increase your understanding. The benefits of drafting in cycling are huge, that's why the peloton nearly always mow down any breakaways, that is unless the peloton are buggering around playing games which they too often do, as was shown at the Melbourne Olympics in the womens 50k road race... what an embarrassment. The peloton just buggered around for about 75% of the race. But once they choose to go, because they have got lots of people drafting, they are using up way less energy as a whole, and are going a lot faster than any lone rider could possibly do.

sAsLEX

10th June 2006, 13:29

Here's a pic of what's happening, it's the best I could do in paint.

The aeros to the rear of something are also very important to achieving aerodynamic goodness.

________
|...........|
|...........|
|...........|
\........../
..\......./
....\.../
......\/

will fall slower than

....../\
...../...\
.../......\
../.........\
|...........|
|...........|
----------

texmo

10th June 2006, 13:35

And heres me thinking racing was easy...

N4CR

10th June 2006, 13:37

And heres me thinking racing was easy...
It is, you just need to learn from the black flame rider and krieg them all. Word.

Hmmm it's all about airflow disturbance really, if you REALLY want I can scan some pages about basic aerodynamics and coefficient of drag between different shape diagrams and stuff like that...

Korea

10th June 2006, 16:42

It is, you just need to learn from the black flame rider and krieg them all. Word.

Hmmm it's all about airflow disturbance really, if you REALLY want I can scan some pages about basic aerodynamics and coefficient of drag between different shape diagrams and stuff like that...
Oo-eeeer~ go on then ~ sounds educational!
Waiting for the update... :wait:

sAsLEX

10th June 2006, 17:37

Oo-eeeer~ go on then ~ sounds educational!
Waiting for the update... :wait:

A real world result of the drag thing http://ame-www.usc.edu/rsg-old/gva/5/5c.htm

N4CR

10th June 2006, 17:38

Oo-eeeer~ go on then ~ sounds educational!
Waiting for the update... :wait:

Oookay I got off my arse and scanned some stuff for you, 1st page is most relevant detailing disturbed airflow and the suction affect it creates..

<IMG SRC=http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=34450&stc=1&d=1149917831>

<IMG SRC=http://www.kiwibiker.co.nz/forums/attachment.php?attachmentid=34451&stc=1&d=1149917831>

Any more questions just ask I'll try explain it better.

vtec

11th June 2006, 14:14

The aeros to the rear of something are also very important to achieving aerodynamic goodness.

Yep, my paint picture takes into account suction from behind the bikes, cause you'll notice that the lines directly behind the bike are far apart, this shows a low pressure zone, or a drag on the rear of the bike.

Also I know that there is a lot of disturbance and vortices in the air around motorbikes, but I was trying to show it as simplistically as possible in it's most useful form for motorbike racing, and my pics are from a combined accumulation of theoretical knowledge, and personal experience on the track, and also from cycling on the road.

Sketchy_Racer

11th June 2006, 14:22

GAH!~!

TO MUCH BRAINY TALK!!!!!!!!!! shessh

sAsLEX

11th June 2006, 15:03

stuff

Just the text on your last written bit in the paint thingy metioned the front bike wasn't much affected by its rear aeros, just pointing out that the rear airflow is just as important as the front.

Mr. Peanut

11th June 2006, 15:39

Here's some disturbing airflow :blip:

http://video.google.com/videoplay?docid=-3111473682011187743

vtec

11th June 2006, 19:13

Just the text on your last written bit in the paint thingy metioned the front bike wasn't much affected by its rear aeros, just pointing out that the rear airflow is just as important as the front.

I didn't say that it wasn't affected at all, I just said that I was pretty sure the rear drag on the trailing bike was less than the frontal drag on the front bike...

In the last picture the front bike is not affected AS MUCH by it's rear aerodynamics, because it has a bike directly behind it keeping the air pressure quite neutral. There is still some drag from swirl effects and things, but a bike drafting behind you does help alleviate drag from behind the front bike. In NASCAR, the positive pressure in front of a trailing car is enough to lessen traction to the rear tyres of the car in front making it less stable... different things happen at different distances from the vehicle in front and at different speeds...

Bert

11th June 2006, 21:50

someone has physics books out:zzzz: :yawn: :innocent:

vtec you missed a great test day yesterday, no rain and quite a warm track, not quite enought streetstockers but we had fun away. catch you sat.

texmo

11th June 2006, 22:10

how come rg100 is the only street stocker racing in f3 as well?

Bert

12th June 2006, 18:50

how come rg100 is the only street stocker racing in f3 as well?

looks like no RG100 in F3 only racey rider (alex) and 3 others

41 Alex Hockly Kawasaki KR150 New Plymouth * * * *
83 Eamon Timms Suzuki RG150 Waikanae *
176 Neil Chappell Suzuki RG150 Waikanae * * * *
267 John Humphery Kawasaki ZXR250 Otorohanga * * * *

Ivan

12th June 2006, 18:59

Yeah he aint in F3 I had his race bike at tech today

vtec

12th June 2006, 22:55

Oh well, can't afford to do everything, plus got to travel from auckland. I'll definitely be racing in F3 at the next meeting aswell, cause I could do with a lot more track time. The bike aint running too flash though. Doesn't like starting any more, and runs on less than 4 cylinders below 10,000rpm. But it still goes alright. I'll be putting in my spare engine after this meeting... finger's crossed it holds up.

texmo

13th June 2006, 18:32

My sensei was helping me strip my bike down for racing and getting it ready ie I was watching him, and one of the radiator hoses broke it should be in by thursday hopefully. I have done all the other stuff that is required and im just sorting out all the finer points now. Like where I am gonna sleep, how many pratise laps do we get?

vtec

13th June 2006, 22:46

Cool, keep up your determination to get there Texmo, and you'll be there. Don't let nerves get in the way, cause if you do, you'll accept any excuse to not make it there.

Well, I decided to do something about the crap running condition of my bike. Stripped it down today, and measured up all the valve clearances, all the intake ones are a bit small, so will be buying a bunch of shims tomorrow and sticking them in. Will put fresh oil and water and spark plugs in when I put it all back together. Hope this fixes it.

Jantar

13th June 2006, 23:02

The slipstream effect extends back for aproximately 2.5 the width of the vehicle you are following. Thae actaul amount of advantage is proportional to the square of the velocity.

So you have be bloody close and travelling bloody fast. Unless you are on the race track forget it.

FROSTY

14th June 2006, 10:41

N4CR

14th June 2006, 17:11

just to throw the cat in there with ya's --has anyone notices the drooppy tails on the modern 125 racers. The whole aim is to reduce the undesturbed air behind the bike to reduce the advantage of slipstreaming

They should have done that anyway to get a better top speed, check the papers I posted they mention form drag - decrease that for a higher C/D and better top speed :)
Less drag you make the better you slip through the air and the higher speed you can get.. simple enough.

Bert

14th June 2006, 20:04

texmo

14th June 2006, 21:33

Just got my radiator hose so I will be there im staying at a place called the race court motel or something apparently its right next to the track.

I have talked over with my old man and im gonna go slow and just try learn the track. I have never ridden on the track and I have never seen manfeild before so its gonna be a big learning curve for me plus I got that shaun harris training day the weekend after so if I stack im stuff not to mention I cant afford to fix the bike.
Hey jason if you bring the van down wanna park next to each other? I have a tarp so we could string it up between cars incase it rains giving us a semi dry place to hide.

cowpoos

14th June 2006, 21:44

vtec

14th June 2006, 21:51

going alright now??? we won't want you hanging with us back markers

Yep, got it back together today, only ran it for a few seconds, but it's back running on all cylinders through the full range. Not sure if it was all cause of the valves, or if it was just the plugs. But hey, it's fine so I'm happy. All the intake valves were measuring 0.11mm or 0.12, they were supposed to be 0.16, so they were definitely outside operating limits of +-0.03mm.

Tex, I'll be staying at the Racecourt Motel aswell, so hopefully we'll be there early enough to have a chat. Yep taking the van, might be a plan... we'll figure it out on the day.

Cowpoos, where did you get the good weather forecast? I saw a bad forecast on tv3 news tonight. :(

texmo

14th June 2006, 21:53

http://www.metvuw.com/forecast/forecast.php?type=rain&region=nzni

Just read the oppoiste might rain hope it doesnt though. are you staying in feilding the night or just riding out from your place?

texmo

14th June 2006, 21:58

Yep, got it back together today, only ran it for a few seconds, but it's back running on all cylinders through the full range. Not sure if it was all cause of the valves, or if it was just the plugs. But hey, it's fine so I'm happy. All the intake valves were measuring 0.11mm or 0.12, they were supposed to be 0.16, so they were definitely outside operating limits of +-0.03mm.

Tex, I'll be staying at the Racecourt Motel aswell, so hopefully we'll be there early enough to have a chat. Yep taking the van, might be a plan... we'll figure it out on the day.

Cowpoos, where did you get the good weather forecast? I saw a bad forecast on tv3 news tonight. :(
cowpoos is a farmer he looked into the sky and hes probbly pritty fucking close he was the last few times hes predicted weather.

I am leaving at midday on friday all the time I could get off work so taking it easy with a stop I guess I will be in feilding at around 9pm or so.

cowpoos

14th June 2006, 22:55

Cowpoos, where did you get the good weather forecast? I saw a bad forecast on tv3 news tonight. :(

I reckon its be sweet at manfield....just coz its a few showers in palmy don't mean it will rain at manfield at all....

marty

15th June 2006, 12:09

slipstreaming works at low speed - anyone who's ridden a push bike in anger knows that draughting at even 30km/h will reduce the effort required by around 30%. your front tyre though, has to be about 10cm off the their rear.

MOTOXXX

15th June 2006, 17:16

hey texmo.
If you have any questions about the race day come find me. ill be in a garage with another rg and a kr. im no 83 on yellow and black rg.
this is my first season racing too so if you have questions gime a yell.

Its two 15 lap sessions so you will have plenty of time to get to know the track.

texmo

15th June 2006, 17:34

OK sweet as thanks man I will see you down there.

The_Dover

15th June 2006, 17:36

OK sweet as thanks man I will see you down there.

Good luck Texmo you little homo.:nya:

If you crash I'll lend you my gixxer.

cowpoos

15th June 2006, 17:40

Good luck Texmo you little homo.:nya:

If you crash I'll lend you my gixxer.
don't encourage him to crash cock!

texmo

16th June 2006, 01:05

Sweet bro, sounds like a plan to me. I cant crash though I need my bike for next weekend too so I am gonna go hard but not push it much. My rear tyre still have a 3cm strip on it...