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Discussion Starter #1
I'm wondering how fast an S1000RR or similar will slow down from wind resistance alone at different speeds from just rolling the throttle off.

Typically VERY hard braking can reduce speed by 22mph/sec. I'm thinking that VERY hard braking at very high speeds should yield more deceleration due to wind resistance. To understand that, I'm wondering what the wind resistance alone would do in speed reduction/sec from 30mph, 60mph, 120mh, 180mph, and 210mph.

I'm aware that there are many variables not the least of which are wind, engine braking, gear, rpm, rider position, downhill/uphill, etc.

I became curious after riding the HP4 Race at The Ridge which has a long flat 6th gear straight into a fast sweeping first turn. So easy to over-slow for the corner. Another one very similar is turn 1 at Phillip Island.
 

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Its too much math for me

Air Resistance Formula

I am sure NASCAR calculates this all the time.

When you said ride position, I was thinking SIZE of rider.

Lois B pops up from behind the windscreen is like a huge wall compared to Danny P popping up in the wind.
 

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Factors such as the coefficient of friction between the tires and the surface play a large roll in traffic collision reconstruction. I have never calculated drag in that manner as wind resistance doesn't usually play a roll in crashes on streets (sub 100MPH) most of the time. You would have to know multiple things to calculate this. The hardest one to pin down is the actual drag coefficient of the motorcycle. Keeping all things equal... flat roadway, consistent roadway friction coefficients, no wind, consistent rider position (upright likely to create the most drag while under hard braking), an engine braking coefficient on a motorcycle is typically around .3 but the new s1000 can vary that to some degree. I would venture to estimate that it's negligible in the totality of the equations though. To be anywhere near the mark you would have to accurately know the drag coefficient of the bike rider combination. Taking information from standards set for by NHTSA they "assume" a drag factor of .45 at 60MPH. Now I can tell you that this must be an AVERAGE between all bikes currently on the roadway... GOLDWING vs S1000RR is much different. In basic drag modeling for motorcycles, rider position can play a factor of around 25% of the total drag factor.

You have my attention I will work on this tomorrow at work and see if I can't get an expert or two to assist.
 

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Actually not so much a physics question as an aerodynamics question. The winglets in MotoGP may actually help under braking as it changes the angle of attack. The fairing on a bike might help a little, but aero drag and effects aren't linear, so they're a lot more effective at higher speed. I remember reading that an F1 car decelerated over 1g simply due to the drag caused by the aero downforce.
 

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:surprise: I brake HARD and have 1.1g deceleration and they have 1g just by downforce:crying:...
Yup, that's what giant aero wings and undertray aero will get ya! F1 cars are designed using rolling windtunnels, extremely expensive, and they pay almost as much attention to aero as NASA does, whereas bike aerodynamics are by comparison crude and about as aerodynamic as a barn door. Bikes are at an extreme disadvantage in having an extremely large frontal area compared to their length. It's extremely important to be able to have the length needed to "close" the air behind you, and bikes (without the old "dustbin" fairings) are simply too short to do it.
 

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I'm wondering how fast an S1000RR or similar will slow down from wind resistance alone at different speeds from just rolling the throttle off.

Typically VERY hard braking can reduce speed by 22mph/sec. I'm thinking that VERY hard braking at very high speeds should yield more deceleration due to wind resistance. To understand that, I'm wondering what the wind resistance alone would do in speed reduction/sec from 30mph, 60mph, 120mh, 180mph, and 210mph.

I'm aware that there are many variables not the least of which are wind, engine braking, gear, rpm, rider position, downhill/uphill, etc.

I became curious after riding the HP4 Race at The Ridge which has a long flat 6th gear straight into a fast sweeping first turn. So easy to over-slow for the corner. Another one very similar is turn 1 at Phillip Island.
Some old measurements what I have done:

Clutch egaged, air drag + rolling resitance:

Tucked down, lower body in the middle
180 kmh -0,200 G
150 kmh -0,155 G
120 kmh -0,100 G

Tucked down, lower body on the side (for the nex turn)
160 kmh -0.215 G
150 kmh -0.180 G
140 kmh -0.165 G
130 kmh -0.140 G
120 kmh -0.125 G

Braking body position (head up, knee on the side)
190 kmh -0,400 G
180 kmh -0,350 G
170 kmh -0,315 G
160 kmh -0,275 G
150 kmh -0,225 G
140 kmh -0,215 G
130 kmh -0,205 G
120 kmh -0,175 G
 

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:surprise: I brake HARD and have 1.1g deceleration and they have 1g just by downforce:crying:...
It is easy to brake max 1.4-1.6G if your bikes front end can handle the load transfer and brake force, and speed is +200 kmh, because air drag gives you an extra 0.4-0.5 G deceleration.
But one problem is also your mindset, if you are used to brake 1.1 G at speeds below 100 kmh and you senses are tuned for that. You must understand that you can brake much harder with the air drag aid and then you must tune your senses to allow much greater deceleration than 1.1 G when speed is +200 kmh.
 

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Discussion Starter #11
Some old measurements what I have done:

Clutch egaged, air drag + rolling resitance:

Tucked down, lower body in the middle
180 kmh -0,200 G
150 kmh -0,155 G
120 kmh -0,100 G

Tucked down, lower body on the side (for the nex turn)
160 kmh -0.215 G
150 kmh -0.180 G
140 kmh -0.165 G
130 kmh -0.140 G
120 kmh -0.125 G

Braking body position (head up, knee on the side)
190 kmh -0,400 G
180 kmh -0,350 G
170 kmh -0,315 G
160 kmh -0,275 G
150 kmh -0,225 G
140 kmh -0,215 G
130 kmh -0,205 G
120 kmh -0,175 G
I'm wondering about something faster like 300km.
 

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It is easy to brake max 1.4-1.6G if your bikes front end can handle the load transfer and brake force, and speed is +200 kmh, because air drag gives you an extra 0.4-0.5 G deceleration.
But one problem is also your mindset, if you are used to brake 1.1 G at speeds below 100 kmh and you senses are tuned for that. You must understand that you can brake much harder with the air drag aid and then you must tune your senses to allow much greater deceleration than 1.1 G when speed is +200 kmh.
My max is 1.4G but usually is around 1G. I think it is not difficult but you need to practice a lot. My nearest track (which is not good at all) unfortunately is 400km away and I even need to travel with a ship :crying:. I manage to go to a good track (Misano) 1-2 times a year and that is it. Track is all about practice and how to manage the data you gather with your senses and datalogger>:).

With AIM software you can even calculate hp of your bike depending also from acceleration/weight/drag coefficient...and it is pretty damn close.
 

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With AIM software you can even calculate hp of your bike depending also from acceleration/weight/drag coefficient...and it is pretty damn close.
Which AIM do you run? Aim solo 2 DL or something else? This is the new hype in EU https://www.raceanalyse.com/english/
Actually about to post a thread about it.

I have been looking to invest into a portable (across bikes) easy to use product without spending months learning what to look at. Part of me just wants to get Solo 2 laptimer, call it a day.
 

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Which AIM do you runner? Aim solo 2 DL or something else? This is the new hype in EU https://www.raceanalyse.com/english/
Actually about to post a thread about it.

I have been looking to invest into a portable (across bikes) easy to use product without spending months learning what to look at. Part of me just wants to get Solo 2 laptimer, call it a day.
I have the AIM MXL2 dash/datalogger. If you just need a GPS lap-timer then yes Solo 2 is a very good solution. I personally suggest you go for Solo 2 DL. It is a lap-timer but you can also connect it with ECU and have way more info, like when and why traction control kicks in, throttle, engine temp, brakes (pressure), suspension etc. combined with GPS info. You can discover sooo many things. But... you need to learn how and what to read. It takes some time but I think if you go to the track, it is worth it 100%.
 

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Discussion Starter #15
@speedfinn can you sustain 1.4g or briefly spike to 1.4g? If you can sustain 1.4g can you show a datalogger screen shot of the acceleration scatter graph? I'm curious what it looks like.
 

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Which AIM do you run? Aim solo 2 DL or something else? This is the new hype in EU https://www.raceanalyse.com/english/
Actually about to post a thread about it.

I have been looking to invest into a portable (across bikes) easy to use product without spending months learning what to look at. Part of me just wants to get Solo 2 laptimer, call it a day.
Get the Solo2 or Solo2DL. I have run through original Solo, Solo DL, HP Datalogger, phone app with GPS BT dongle, HP IR beacon, only my X2 MyLaps transponder and am back to the Solo laptimers (Now a Solo2DL). Makes the most sense. Easy to use, software included, track auto recognized, swapable between bikes and I have never had any issues with any of the units I have owned. Even had my original Solo fly off the bike at 130 MPH. LCD was bleeding but was able to send it in and get repaired with quick turnaround time and very reasonable cost.

Working on something during a session and having the ability to check immediately if your laptimes have improved is so much better than waiting to pit, download data and review the data on a PC. Predictive lap time is helpful as well to know just how bad you blew that last corner coming in hot.....

I have both versions in stock if you are interested. Another great thing is these things retain their value! Used units always command a premium.

https://soflosbk.com/products/aim-solo-2-and-solo-2-dl
 

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Get the Solo2 or Solo2DL. I have run through original Solo, Solo DL, HP Datalogger, phone app with GPS BT dongle, HP IR beacon, only my X2 MyLaps transponder and am back to the Solo laptimers (Now a Solo2DL). Makes the most sense. Easy to use, software included, track auto recognized, swapable between bikes and I have never had any issues with any of the units I have owned. Even had my original Solo fly off the bike at 130 MPH. LCD was bleeding but was able to send it in and get repaired with quick turnaround time and very reasonable cost.

Working on something during a session and having the ability to check immediately if your lap times have improved is so much better than waiting to pit, download data and review the data on a PC. Predictive lap time is helpful as well to know just how bad you blew that last corner coming in hot.....

I have both versions in stock if you are interested. Another great thing is these things retain there value! Used units always command a premium.

https://soflosbk.com/products/aim-solo-2-and-solo-2-dl
Just wondering if you had combined the BMW data logger with a Solo2 lap timer... would that be a better combination? Watching @smash adams show me his data from the BMW data logger made me drool. Agree with the immediate lap time confirmation on the Solo. I have always tried not to look at the timer on the track itself. There have been times I've just had to sneak a peak for confirmation. It's not a regular thing.
 

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@speedfinn can you sustain 1.4g or briefly spike to 1.4g? If you can sustain 1.4g can you show a datalogger screen shot of the acceleration scatter graph? I'm curious what it looks like.
Sorry to say this, but your question is a little bit stupid. Because if you are braking, you can not sustain speed, and if you can not sustain speed you can not sustain air drag, and if you can not sustain air drag, you can not sustain 1.4G deceleration.
Do you get it...?

And as I said earlier:"It is easy to brake max 1.4-1.6G if your bikes front end can handle the load transfer and brake force, and speed is +200 kmh, because air drag gives you an extra 0.4-0.5 G deceleration."

So note that your bikes front end must cope the load transfer (rider mass + bike mass - front end unsprung mass) and brake force (total mass x front wheel braking force "x" caster angle).

For example my bikes front end has 11.5 springs and an extra 5 mm suspension travel (K-Tech cartridges). And when I am braking, it bottoms out, but does not bottom out too much. That extra 5 mm is very usefull when braking very hard.

If front end bottoms out too much, then it starts to squirm, and also rear end jumps up, and that makes it impossible to brake hard even if you would have skills to brake hard. You just can not compensate front end inadequate load carrying capacity with braking skills.

But anyhow, here is a couple of examples, max 1.4 G and 1.6 G, and then trail braking to apex (or at least trying...) with "linear" easing of brakes and adding lean angle.

 

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Just wondering if you had combined the BMW data logger with a Solo2 lap timer... would that be a better combination? Watching @smash adams show me his data from the BMW data logger made me drool. Agree with the immediate lap time confirmation on the Solo. I have always tried not to look at the timer on the track itself. There have been times I've just had to sneak a peak for confirmation. It's not a regular thing.
In your case BMW HP Datalogger for data. And some cheap Android phone (used, ebay, 20usd or so) with RaceChrono and XGPS160 for laptiming could be good solution. Laptiming accuracy with 10 Hz GPS is about 0.01 seconds.

I'm using the same combination.
 
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