Not Trailing Braking & Lap Times

[YellowDuck]

Timing the brake release with the turn-in is easier than many might expect. To start, enter a corner at a slower-than-usual pace, brake lighter than usual (because you are going slower), and release the brake as you bend the bike in. If you turn in slowly, you can release the brake slowly. If you turn in quickly, you must release the brake quickly.

 

 

Ha, you're right, and I am already getting it right sometimes! Just reviewed some track footage from this year showing the front fork action, and even when I am turning it in hard I am not experiencing much fork rebound between braking and turn in. For example check out the three corners beginning at 8:45 in this video:

 

 

The one at 8:50 is a bit of a slow turn-in (big braking corner after a long-ish straight) but the next two I think I flick it in pretty quick (by my standards) but there is no real rebound from the compression under braking. Of course it can get better but it is working better than I expected just thinking about it.

[Dylan Code]

Exactly. I saw the video section that you referenced and it appears that you did a good job at keeping the forks evenly compressed during the transition from brake release to leaned over in the corner.

[YellowDuck]

Not to change the topic, but another thing I noticed is that the fastest lap (by far) in that video is the one where I brake the latest and hardest at the end of the straight (braking starts about 10:00) - you can see the front tire getting pretty squirmy, and I actually bump the zip tie on the fork a smidge. I know CSS is not big on super hard late braking, but in my case when I get that right it seems to make a difference. Probably that's just a measure of how poor my braking points normally are. Especially at the end of a long straight I have a tendency to coast or at least not brake very hard at some point during the setup for the corner. I think I need to work a lot harder at identifying braking markers, and moving them forward when possible. If there is time to coast, then there was room to brake later!

[Dylan Code]

Not to change the topic, but another thing I noticed is that the fastest lap (by far) in that video is the one where I brake the latest and hardest at the end of the straight (braking starts about 10:00) - you can see the front tire getting pretty squirmy, and I actually bump the zip tie on the fork a smidge. I know CSS is not big on super hard late braking, but in my case when I get that right it seems to make a difference. Probably that's just a measure of how poor my braking points normally are. Especially at the end of a long straight I have a tendency to coast or at least not brake very hard at some point during the setup for the corner. I think I need to work a lot harder at identifying braking markers, and moving them forward when possible. If there is time to coast, then there was room to brake later!

Of course what you are saying is correct. The only thing I need to correct is where you say "CSS is not big on super hard late braking". Braking is braking and you can and should brake as hard as you want as long as you don't find yourself rushing to a corner in a fashion that makes your entry rough or on the edge of crashing. Motorcycles only have so much braking capability and they have not changed much for decades on the straight line 60mph to 0mph stops. Compare the 60-0 stopping distance of a 1983 Honda Interceptor and a 2014 Yamaha R1. They are the same or within a few feet. You can only get about 1.0g's maximum of braking unless you have added downforce (like a wing on a car), uphill, added wind resistance (parachute or very large surface area), or at very high speeds where the wind resistance is extreme.

[Dylan Code]

Oh, I am still waiting on the answer to this question...

How does this apply to a series of corners (s-curves) that you're trying to go faster through? In other words, what must you do to be able to go faster through a series of corners? It depends of the series of corners. Are they fast in slow out, or slow in fast out?

Why does that matter? I was going along with the orignal theme of the thread. For those that trail brake "in the fast in slow out" could be hampered by how quick they can turn, at least for the first turn. So which steering rule would you apply?

Jeff

Scrmduc,

 

You seem to have unanswered questions but with all this back and forth I'm a little lost. It seems like some questions are asking, but some also may be rhetorical. Why don't you bullet out a little list for me and I'll see about answering.

[ktk_ace]

 

Not to change the topic, but another thing I noticed is that the fastest lap (by far) in that video is the one where I brake the latest and hardest at the end of the straight (braking starts about 10:00) - you can see the front tire getting pretty squirmy, and I actually bump the zip tie on the fork a smidge. I know CSS is not big on super hard late braking, but in my case when I get that right it seems to make a difference. Probably that's just a measure of how poor my braking points normally are. Especially at the end of a long straight I have a tendency to coast or at least not brake very hard at some point during the setup for the corner. I think I need to work a lot harder at identifying braking markers, and moving them forward when possible. If there is time to coast, then there was room to brake later!

Of course what you are saying is correct. The only thing I need to correct is where you say "CSS is not big on super hard late braking". Braking is braking and you can and should brake as hard as you want as long as you don't find yourself rushing to a corner in a fashion that makes your entry rough or on the edge of crashing. Motorcycles only have so much braking capability and they have not changed much for decades on the straight line 60mph to 0mph stops. Compare the 60-0 stopping distance of a 1983 Honda Interceptor and a 2014 Yamaha R1. They are the same or within a few feet. You can only get about 1.0g's maximum of braking unless you have added downforce (like a wing on a car), uphill, added wind resistance (parachute or very large surface area), or at very high speeds where the wind resistance is extreme.

 

 

does electronics count?

eg:

-CBS (combined braking system)

-TC (traction control)

-EBM (engine braking management)

[Dylan Code]

 

 

does electronics count?

eg:

-CBS (combined braking system)

-TC (traction control)

-EBM (engine braking management)

 

No, electronics will not change the maximum available stopping distances compatred to a skilled rider without these aids. Look at it like this: the earth is pulling you down with 1g, if you try to generate more than 1g in force laterally, you will start to endo or lock up. Unless of course there is additional downforce, lots of wind resistance from high speeds, etc.

[ktk_ace]

 

 

 

does electronics count?

eg:

-CBS (combined braking system)

-TC (traction control)

-EBM (engine braking management)

 

No, electronics will not change the maximum available stopping distances compatred to a skilled rider without these aids. Look at it like this: the earth is pulling you down with 1g, if you try to generate more than 1g in force laterally, you will start to endo or lock up. Unless of course there is additional downforce, lots of wind resistance from high speeds, etc.

 

Thanks for clearing it up

[faffi]

I do not subscribe to MOTORRAD anymore, but I remember they stopped the K1300R in 36 metres from 100 kph (one G is about 39 metres) with ABS. At that point, it was the only bike where their test rider couldn't match the ABS, even after several attempts. At the same test, the Honda Fireblade stopped in 42 metres, quite typical for sportbikes. So why did the K, which is a lot heavier, stop so much better? Because it is long and low, meaning it can use both wheels for slowing and it will not endo. Short bikes with a high CoG is, as Code mentioned, limited because they want to roll over their front wheel well before all grip is used up. It's the price you pay for quick steering and loads of cornering clearance.

 

BTW, the first bike to beat the 40 metre limit in the German magazine's history was the RD350 L/C back in 1980, skinny tyres and all. It stopped in 39 metres.

[Dylan Code]

So there you go, almost all very good 60-0 stops are going to be around 120ft. If you can get an 18 wheeler to develop 1g in braking force, it will stop in the same distance. Weight does not matter so much as good brakes and a good sticky contact with the road. I saw footage of an army tank that could stop very quickly. It had good brakes and sticky rubber treads.

 

Why could someone get a better than 1g stop? As was previously mentioned: large surface area=wind resistance, or maybe a headwind, or maybe a slight uphill, or some aerodynamic feature that adds some downforce, which would be most noticeable at the beginning of the braking action at 60mph. If you can go straight to max braking pressure at 60mph, you are going to getting better than 1g because of the max braking plus wind resistance at the higher spped. Having ABS would possibly allow the rider to go to max pressure a little quicker. Even if it was a 1/10 of a second quicker, that would make a difference especially at higher speeds where the feet-per-second is so much higher. A 1/10th of a second at 60mph is 8.8 feet.

 

If you find a particularly good or bad stop on a motorcycle it usually has its roots in what happened when the brake was initially engaged.

 

C of G will have some bearing but it would be hard to do anything but speculate without hard facts (measurements) and someone well-trained in physics, which I am not.

 

(answered quickly not checked for typos)

[ktk_ace]

I do not subscribe to MOTORRAD anymore, but I remember they stopped the K1300R in 36 metres from 100 kph (one G is about 39 metres) with ABS. At that point, it was the only bike where their test rider couldn't match the ABS, even after several attempts. At the same test, the Honda Fireblade stopped in 42 metres, quite typical for sportbikes. So why did the K, which is a lot heavier, stop so much better? Because it is long and low, meaning it can use both wheels for slowing and it will not endo. Short bikes with a high CoG is, as Code mentioned, limited because they want to roll over their front wheel well before all grip is used up. It's the price you pay for quick steering and loads of cornering clearance.

 

BTW, the first bike to beat the 40 metre limit in the German magazine's history was the RD350 L/C back in 1980, skinny tyres and all. It stopped in 39 metres.

 

the k1300R is by no means conventional... it has a very special front setup

 

Front duolever.

 

http://www.carbibles.com/suspension_bible_bikes.html

http://www.motorcyclenews.com/upload/219848/images/01bmw-k1300-r.jpg

 

[faffi]

So there you go, almost all very good 60-0 stops are going to be around 120ft. If you can get an 18 wheeler to develop 1g in braking force, it will stop in the same distance. Weight does not matter so much as good brakes and a good sticky contact with the road. I saw footage of an army tank that could stop very quickly. It had good brakes and sticky rubber treads.

 

Why could someone get a better than 1g stop? As was previously mentioned: large surface area=wind resistance, or maybe a headwind, or maybe a slight uphill, or some aerodynamic feature that adds some downforce, which would be most noticeable at the beginning of the braking action at 60mph. If you can go straight to max braking pressure at 60mph, you are going to getting better than 1g because of the max braking plus wind resistance at the higher spped. Having ABS would possibly allow the rider to go to max pressure a little quicker. Even if it was a 1/10 of a second quicker, that would make a difference especially at higher speeds where the feet-per-second is so much higher. A 1/10th of a second at 60mph is 8.8 feet.

 

If you find a particularly good or bad stop on a motorcycle it usually has its roots in what happened when the brake was initially engaged.

 

C of G will have some bearing but it would be hard to do anything but speculate without hard facts (measurements) and someone well-trained in physics, which I am not.

 

(answered quickly not checked for typos)

 

In theory, you cannot go beyond 1g (if we ignore wind resistance). In reality, you can. Although never fully explained AFAIK, the soft rubber and textured road surface interact a bit like gears, allowing more than one G of force. Which is why motorcycles can corner beyond 45 degrees of lean and stop quicker than one G. And why dragsters can accelerate from 0-60mph in under half a second, which should be around 3g if I'm not too far off with my math. Formula 1 cars can stop and corner at up to 5g thanks to artificial downforce.

 

For those who want to calculate the effect of wheelbase and CoG and weight and friction and whatnot, everything is explained very well here http://books.google.no/books?id=rJTQxITnkbgC&pg=PA97&lpg=PA97&dq=motorcycle+cog+effect+on+braking&source=bl&ots=DYjQDaaQqF&sig=hOVa-7Rde0vwqG0lY5RlkgSEumQ&hl=en&sa=X&ei=DqMNU_vDGanf4QS3lICgBA&ved=0CCcQ6AEwAA#v=onepage&q&f=false

[Dylan Code]

 

So there you go, almost all very good 60-0 stops are going to be around 120ft. If you can get an 18 wheeler to develop 1g in braking force, it will stop in the same distance. Weight does not matter so much as good brakes and a good sticky contact with the road. I saw footage of an army tank that could stop very quickly. It had good brakes and sticky rubber treads.

 

Why could someone get a better than 1g stop? As was previously mentioned: large surface area=wind resistance, or maybe a headwind, or maybe a slight uphill, or some aerodynamic feature that adds some downforce, which would be most noticeable at the beginning of the braking action at 60mph. If you can go straight to max braking pressure at 60mph, you are going to getting better than 1g because of the max braking plus wind resistance at the higher spped. Having ABS would possibly allow the rider to go to max pressure a little quicker. Even if it was a 1/10 of a second quicker, that would make a difference especially at higher speeds where the feet-per-second is so much higher. A 1/10th of a second at 60mph is 8.8 feet.

 

If you find a particularly good or bad stop on a motorcycle it usually has its roots in what happened when the brake was initially engaged.

 

C of G will have some bearing but it would be hard to do anything but speculate without hard facts (measurements) and someone well-trained in physics, which I am not.

 

(answered quickly not checked for typos)

 

In theory, you cannot go beyond 1g (if we ignore wind resistance). In reality, you can. Although never fully explained AFAIK, the soft rubber and textured road surface interact a bit like gears, allowing more than one G of force. Which is why motorcycles can corner beyond 45 degrees of lean and stop quicker than one G. And why dragsters can accelerate from 0-60mph in under half a second, which should be around 3g if I'm not too far off with my math. Formula 1 cars can stop and corner at up to 5g thanks to artificial downforce.

 

 

1g is going to be 22mph/sec and 0-60 in .5 sec= 120mph in a second. So how many G's does that come out in your math?

 

However empirically we can see that this theoretical concept of 1G helps us understand braking and accelleration in a fashion that gives us real expectations when slowing down a motorcycle as well as the idea of introducing cornering force while braking.

 

So how many G's does the fastest production car in the world pull when accelerating to 270mph from a stop?

 

Here's your answer at 0:50 of the video

 

 

 

*excuse tyops*

[faffi]

1g is going to be 22mph/sec and 0-60 in .5 sec= 120mph in a second. So how many G's does that come out in your math?

Average speed will be 60 mph (with even acceleration), so 60:22 ~ 3g. In my math But I've been wrong before and I'm happy to be proven wrong again

[Dylan Code]

Well if you had an average of 1g acceleration for 3 seconds, that would be 66mph after 3 seconds. You'll also notice that most 0-60 times on modern sportbikes are right around 3 seconds.

 

So if you went 0-60 in 0.5 seconds, that would be almost six times the acceleration. It would be about 5.4g's per my reckoning.

[faffi]

So probably time to upgrade my math, then

[ktk_ace]

So probably time to upgrade my math, then

well better late than never

[Darth Peachy]

Not being a track rider I can't speak from experience in terms of speed. My playground is on mountain and country roads where the conditions of the road can change from one day to the next. I seldom use my back brake except for in slow moving traffic, maneuvering on a gradient and in the wet when I don't want my front end to slide out from under me by grabbing too much front brake. So I basically just use my back brake to feather my braking, it makes breaking a lot less harsh and is essential around town in slow moving traffic.

[Dylan Code]

Not being a track rider I can't speak from experience in terms of speed. My playground is on mountain and country roads where the conditions of the road can change from one day to the next. I seldom use my back brake except for in slow moving traffic, maneuvering on a gradient and in the wet when I don't want my front end to slide out from under me by grabbing too much front brake. So I basically just use my back brake to feather my braking, it makes breaking a lot less harsh and is essential around town in slow moving traffic.

I do the same myself on the street.

[ScrmnDuc]

 

Oh, I am still waiting on the answer to this question...

How does this apply to a series of corners (s-curves) that you're trying to go faster through? In other words, what must you do to be able to go faster through a series of corners? It depends of the series of corners. Are they fast in slow out, or slow in fast out?

Why does that matter? I was going along with the orignal theme of the thread. For those that trail brake "in the fast in slow out" could be hampered by how quick they can turn, at least for the first turn. So which steering rule would you apply?

Jeff

Scrmduc,

 

You seem to have unanswered questions but with all this back and forth I'm a little lost. It seems like some questions are asking, but some also may be rhetorical. Why don't you bullet out a little list for me and I'll see about answering.

 

Thank you for asking Dylan,

All is good and thanks again for asking.

 

Jeff