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No Brakes, Questions?


acebobby
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I am a big fan of the techniques and procedures taught at the CSS but this procedure has been messing with my head lately and I would like experts opinions on the subject!

With onbike camera technology at the level its at these days in Moto GP and WSBK we can see how much the front tyre deforms on the brakes effectively increasing the contact patch on the front tyre at the turn in point, this must increase grip levels at that point in the turn! would these guys be able to take the turns at the same speeds if they were riding no brakes or do they need the braking forces to give a little extra grip at the turn point?

 

Bobby

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Moto GP tires are designed for high loads and they only run about 15 psi in their tires. So they need to be ridden much differently then the tires we can get out hands on. A few years ago I do remember hearing a rider comment how much load they needed to keep on the tires otherwise they had no grip.

 

DOT tires are designed to have grip at all times even when fairly cold. Moto GP tires are designed to handle maximum loads for many laps at a time and nothing less. So they are two opposite ends of the spectrum.

 

I've never ridden a Moto GP bike but thats the way it seems to me from the information I've gathered.

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Interesting question, I have one of my own...

 

I think it is pretty well understood that there are basically two variables that generate load on the front tire.

 

  1. Braking
  2. Cornering

 

The weight on the tires (motorcycle and rider is pretty constant). So we can place load on the front tire by applying the brake. Also load is placed on the front tire when the bike changes direction as well.

 

One of the tenants of trail braking is that you only have 100% of traction available for both variables. Even the best MotoGP tire can be over loaded if you apply too much braking force or too much cornering force or some combination of the two that is greater then the tire can provide, in other words more then 100%. I think basically there are two ways to generate more cornering load, go faster or turn harder.

 

So lets say that under normal circumstances a MotoGP rider uses 70% of the load for braking and 30% for cornering.

 

 

 

Wouldn't it stand to reason that if they had very large attachments, they could use 100% of the load for cornering only?

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Stuman, with his very large attachements, hilarious!

 

And he nicely brought up how to look at this subject, a puzzling subject to many. So, what do you guys think?

 

CF

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Interesting question, I have one of my own...

 

I think it is pretty well understood that there are basically two variables that generate load on the front tire.

 

  1. Braking
  2. Cornering

 

The weight on the tires (motorcycle and rider is pretty constant). So we can place load on the front tire by applying the brake. Also load is placed on the front tire when the bike changes direction as well.

 

One of the tenants of trail braking is that you only have 100% of traction available for both variables. Even the best MotoGP tire can be over loaded if you apply too much braking force or too much cornering force or some combination of the two that is greater then the tire can provide, in other words more then 100%. I think basically there are two ways to generate more cornering load, go faster or turn harder.

 

So lets say that under normal circumstances a MotoGP rider uses 70% of the load for braking and 30% for cornering.

 

 

 

Wouldn't it stand to reason that if they had very large attachments, they could use 100% of the load for cornering only?

 

Even though I have heard GP riders say they need to keep the front tire loaded otherwise it lets go I'm still having a hard time understanding how that would work. For example the tire has enough grip when loaded 80% or 100% but it slips at 90% (to the point they might wreck). I could definitely see them losing the front end while accelerating and leaned over because the front tire is barely on the ground.

 

I'm probably just misinterpreting what I've heard even though I don't seem to be the only one. They are probably saying they need to keep it heavily loaded otherwise it doesn't stay up to its best operating temperature. If they don't load it, tire temps drop and they lose grip. That would make MUCH more sense.

 

 

 

 

Ben Spies seems to be pretty open talking about his Moto GP experience, anyone have his phone number? laugh.gif

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Hi Ace,

 

If you get/have a description or quote, that might help narrow this down a bit.

 

The throttle is the in-turn load adjuster in terms of weight front/back. I wonder if you might be on the mark with your comment about tire temps though. We know for sure that tire temps can change quite a bit if one is not riding them in the correct range, meaning too slow, or the wrong tire for the conditions/track.

 

CF

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To kinda help with the question and where I thought the discussion would come around to (ahem, if you don't mind Sir Ace) would the available grip levels be the same in a no-brakes quick turn scenario? Is it more likely that the front would push if the speed were too high before the direction change?

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I'm loosing sight of what I tried to say here but let me try to put a couple of examples of what I mean up,

picture a corner, maybe entry speed 60 mph, scenario 1 you go no brakes, arive at your desired turn point at 60, turn and do the corner!

scenario 2 you brake very hard from a high speed approaching your turn point, arrive at your turn point at 60, turn in and do the corner!

No trail braking or anything, just simply getting to your turn point and turning, would scenario 2 not give a bit more front end grip than scenario 1 right at the turn point?

hope this makes sense

 

Bobby

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...picture a corner, maybe entry speed 60 mph, scenario 1 you go no brakes, arive at your desired turn point at 60, turn and do the corner!

scenario 2 you brake very hard from a high speed approaching your turn point, arrive at your turn point at 60, turn in and do the corner!

No trail braking or anything, just simply getting to your turn point and turning, would scenario 2 not give a bit more front end grip than scenario 1 right at the turn point?

Bobby

That's a great question Bobby...beyond my pay grade mind you but you framed it very well.

BTW, I dunno the answer but do understand the question. wink.gif

 

Rain

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...picture a corner, maybe entry speed 60 mph, scenario 1 you go no brakes, arive at your desired turn point at 60, turn and do the corner!

scenario 2 you brake very hard from a high speed approaching your turn point, arrive at your turn point at 60, turn in and do the corner!

No trail braking or anything, just simply getting to your turn point and turning, would scenario 2 not give a bit more front end grip than scenario 1 right at the turn point?

Bobby

That's a great question Bobby...beyond my pay grade mind you but you framed it very well.

BTW, I dunno the answer but do understand the question. wink.gif

I can't say I know (or even understand) the answer, but let's pitch the two situations against each other from a physics point of view:

 

The "no braking" entry, with a steady pace:

  • The front tire just rolls along, with approx 40-45% of the load from the bike+pilot on it.

The "hard braking entry, with a gas-it, brake-it pace:

  • During the acceleration phase, lets than 40% of the weight is placed on the tyre, due to the gas transferring most or even all the weight to the rear tyre. Hence, the tyre will deform less and thereby generate less heat in it.
  • During the braking phase, almost 100% of the weight is transferred to the front tyre, deforming it from the forces and also some of the kinetic energy from the bike is bound to end up at heat in the tyre. Thus, the tyre should see a significant heating from the braking action.

Unless I have missed something obvious (if I have, do speak up please!), the braking entry is bound to give you a warmer tyre, which in turn should give you more grip*. If I understand the tyre experts right, the difference between a race tyre and a road tyre is that a race tyre offers a very high level of grip, but in a rather narrow temperature range, whereas a road tyre is designed to yield a good level of grip (but not quite as high as from a race tyre), but over a fairly broad range of temperature.

 

*) assuming that the tyre isn't decomposing from the heat, of course

 

 

So yes, I think ACE is right in claiming that the braking action will give you a better grip level. The question remains: do they actually need this extra grip in order to make the turn? I haven't seen any of the motoGP races this year, but I recall at least Stoner explaining that he had a hard time "loading up the front end" to get the grip that he wanted.

 

If that's the case, then maybe we're killing two birds with one stone in this thread!

 

Cheers,

 

Kai

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The problem is that few, if any, at this board understand how close to the ragged edge of disaster the fastest GP riders are at all times. Listning to the OTT interviews with Spies gives just a hint of insight, although I still cannot phatom what we're really talking about in experience. Finding that final second in a lap is so hard, it's left for a handful of people to discover. And even for them it's a constant balance act at the very limit of disaster.

 

Which is probably why Kevin Schwantz, for one, found test riders of little value; if they were one second slower, sometimes only .5 of seconds slower, than himself, their information were virtually useless because a bike that worked fine (or very badly) at a pace a second slower could become an animal (or become right) once you went that little extra faster.

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Don't know that braking (upright at any rate) will warm the sides of the tire as much as needed, though trailing it off would add some heat.

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Here's my contribution:

(see Ace, I told ya I would help out, I had an idea that this is where you were going as I had thought of something similar, just hadn't quite put the words together)

 

To turn a motorcycle we must countersteer. It is this counterseering action that forces the bike off-balance and to shift in the opposite direction of the bar motion.

 

Does a tire deform when steered? What causes a pushing front to gain traction and steer the bike into the turn? Does it tend more to push on the countersteer or pro-steer?

 

If we can answer these questions, we're a step closer to Ace's question (which we'll need to NOT discuss the different geometries in the different scenarios, but I dunno if we can really do that and arrive at a real answer).

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OK, a few good coments here but I wasn't really thinking of the braking forces heating the tyre but more the fact that the front contact patch will be deformed under braking forces momentarily increasing the size of the contact patch, so if you have a turn where you have managed to finish your braking exactly at your turn point, would the bigger contact patch created at that moment not give the bike more front end grip?

As I said if you have managed to have absolutely no coasting between off the brakes and your turn point!

 

Bobby

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OK, a few good coments here but I wasn't really thinking of the braking forces heating the tyre but more the fact that the front contact patch will be deformed under braking forces momentarily increasing the size of the contact patch, so if you have a turn where you have managed to finish your braking exactly at your turn point, would the bigger contact patch created at that moment not give the bike more front end grip?

As I said if you have managed to have absolutely no coasting between off the brakes and your turn point!

 

Bobby

 

Well your tires only have so much grip available at any given time, it doesn't matter how much grip they have at any certain point as long as you can use all of it without going over the limit. If your using 50% for trail braking and 50% for cornering you can't turn as tight as if you were using 100% for cornering. Would you rather use your grip for maintaining corner speed or slowing down?

 

Cobie, the articles that I've seen riders (primarily Casey Stoner) saying the need to keep the front tire loaded to make them grip were all from reporters talking to the rider and posting them on sites like MotoMatters.com. I'm not sure which site I've seen it on either because its been a pretty long time sense I've seen any riders comment on it but for all I know they could just be making excuses.

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A friend I ride with has an RC51. At a track day last year he was telling me he was riding the front brake through turns to help keep the front end planted. He uses Michelin Power Race tires and rides in the intermediate class. I highly question whether he actually needs to run race tires at a track day at his skill level. I personally think it's a waste of money, but that is a topic for another thread (probably already covered if I did a search).

 

I now know where he got this idea of braking in the turn.

 

I do however question some things.

 

1) Is he really riding to the limit and needs to do this or is he just mimicing the pros because this is what they do?

 

2) Doesn't this steal some traction from turning? (possibly the point of the the OP)

 

3) Wouldn't this actually slow you down? I know he is on the throttle while braking in the corner.

 

4) The point of being on the throttle in the turn is to transfer weight to the bigger rear tire and off the front tire to keep it from sliding out. How could this technique possibly help a non-pro rider? (assuming the pros aren't just blowing smoke)

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OK, a few good coments here but I wasn't really thinking of the braking forces heating the tyre but more the fact that the front contact patch will be deformed under braking forces momentarily increasing the size of the contact patch, so if you have a turn where you have managed to finish your braking exactly at your turn point, would the bigger contact patch created at that moment not give the bike more front end grip?

As I said if you have managed to have absolutely no coasting between off the brakes and your turn point!

 

Bobby

 

So, observation no.1 what happens when you come of the brakes? does the tyre stay deformed? Does the suspension still load the tyre? Or does something else happen?

 

Thinking about that then, and your inital thoughts Bobby, what difference does this make to your two scenarios now? No trail braking, you're off the brakes before the TP, and...?

 

Bullet

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A friend I ride with has an RC51. At a track day last year he was telling me he was riding the front brake through turns to help keep the front end planted. He uses Michelin Power Race tires and rides in the intermediate class. I highly question whether he actually needs to run race tires at a track day at his skill level. I personally think it's a waste of money, but that is a topic for another thread (probably already covered if I did a search).

 

I now know where he got this idea of braking in the turn.

 

I do however question some things.

 

1) Is he really riding to the limit and needs to do this or is he just mimicing the pros because this is what they do?

 

2) Doesn't this steal some traction from turning? (possibly the point of the the OP)

 

3) Wouldn't this actually slow you down? I know he is on the throttle while braking in the corner.

 

4) The point of being on the throttle in the turn is to transfer weight to the bigger rear tire and off the front tire to keep it from sliding out. How could this technique possibly help a non-pro rider? (assuming the pros aren't just blowing smoke)

 

Michelin power race tyres is a brand, not specifically meaning they're racing tyres. They are a track/road tyre and they're very good for reference.

 

1) unlikley.

 

2) No, but he does increase his chances of a lowside by doing so.

 

3) No, there is race lap time performance to be had by doing this, braking later into the turn and carrying more into the turn, but also see point 2. He wouldn't (well shouldn't), be braking all the way through the turn, that's completely uneccesary, you either brake, or use the throttle, not both to my mind.

 

4)Yes, that's right, the application of throttle does transfer the weight, though you can (and I don't reccomend it any beginner/moderate level), to brake into the turns (see point 2). What in essence happens, is the rider leverages the exceptional grip levels of the modern tyres and gets away with it. and thus thinks its something you can/should do.#

 

The reality if using the brakes with the bike leaned over is possible, though if you look at top level riders, as they increase lean angle, the brake lever pressure decreases. So lots of brake straight upright, and release pressure from turn point into the turn. How far you can go into the turn depends on the type of turn, how the bike is setup, the grip you have and so on. Reccomended. Not until it's really becoming your limiting factor to going really fast, No.

 

Bullet

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OK, a few good coments here but I wasn't really thinking of the braking forces heating the tyre but more the fact that the front contact patch will be deformed under braking forces momentarily increasing the size of the contact patch, so if you have a turn where you have managed to finish your braking exactly at your turn point, would the bigger contact patch created at that moment not give the bike more front end grip?

As I said if you have managed to have absolutely no coasting between off the brakes and your turn point!

 

Bobby

 

So, observation no.1 what happens when you come of the brakes? does the tyre stay deformed? Does the suspension still load the tyre? Or does something else happen?

 

Thinking about that then, and your inital thoughts Bobby, what difference does this make to your two scenarios now? No trail braking, you're off the brakes before the TP, and...?

 

Bullet

 

OK I guess looking at it this way, if your off the brakes before the turn pount the two scenarios are the same! Something I have been working on recently is reducing the coasting between off the brakes and my turn point, so the easiest way I found to do this was to make my turn point my off the brakes marker too and riding this way seems to make it feel like there's a little bit more weight over the front at my turn point, it could be psychological though!

 

Bobby

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A friend I ride with has an RC51. At a track day last year he was telling me he was riding the front brake through turns to help keep the front end planted. He uses Michelin Power Race tires and rides in the intermediate class. I highly question whether he actually needs to run race tires at a track day at his skill level. I personally think it's a waste of money, but that is a topic for another thread (probably already covered if I did a search).

 

I now know where he got this idea of braking in the turn.

 

I do however question some things.

 

1) Is he really riding to the limit and needs to do this or is he just mimicing the pros because this is what they do?

 

2) Doesn't this steal some traction from turning? (possibly the point of the the OP)

 

3) Wouldn't this actually slow you down? I know he is on the throttle while braking in the corner.

 

4) The point of being on the throttle in the turn is to transfer weight to the bigger rear tire and off the front tire to keep it from sliding out. How could this technique possibly help a non-pro rider? (assuming the pros aren't just blowing smoke)

 

Michelin power race tyres is a brand, not specifically meaning they're racing tyres. They are a track/road tyre and they're very good for reference.

 

1) unlikley.

 

2) No, but he does increase his chances of a lowside by doing so.

 

3) No, there is race lap time performance to be had by doing this, braking later into the turn and carrying more into the turn, but also see point 2. He wouldn't (well shouldn't), be braking all the way through the turn, that's completely uneccesary, you either brake, or use the throttle, not both to my mind.

 

4)Yes, that's right, the application of throttle does transfer the weight, though you can (and I don't reccomend it any beginner/moderate level), to brake into the turns (see point 2). What in essence happens, is the rider leverages the exceptional grip levels of the modern tyres and gets away with it. and thus thinks its something you can/should do.#

 

The reality if using the brakes with the bike leaned over is possible, though if you look at top level riders, as they increase lean angle, the brake lever pressure decreases. So lots of brake straight upright, and release pressure from turn point into the turn. How far you can go into the turn depends on the type of turn, how the bike is setup, the grip you have and so on. Reccomended. Not until it's really becoming your limiting factor to going really fast, No.

 

Bullet

 

 

Ok, I am with you on the tire question. It's a trade name, not a race tire.

 

And now for some other clarifications. I can be anal at times, don't take it as me being cheeky. ;)

 

 

1) Which is unlikely? Riding to the limits or mimicking the pros?

 

3) I understand braking later will help lap times. He is dong this throughout the turn.

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A friend I ride with has an RC51. At a track day last year he was telling me he was riding the front brake through turns to help keep the front end planted. He uses Michelin Power Race tires and rides in the intermediate class. I highly question whether he actually needs to run race tires at a track day at his skill level. I personally think it's a waste of money, but that is a topic for another thread (probably already covered if I did a search).

 

I now know where he got this idea of braking in the turn.

 

I do however question some things.

 

1) Is he really riding to the limit and needs to do this or is he just mimicing the pros because this is what they do?

 

2) Doesn't this steal some traction from turning? (possibly the point of the the OP)

 

3) Wouldn't this actually slow you down? I know he is on the throttle while braking in the corner.

 

4) The point of being on the throttle in the turn is to transfer weight to the bigger rear tire and off the front tire to keep it from sliding out. How could this technique possibly help a non-pro rider? (assuming the pros aren't just blowing smoke)

 

Michelin power race tyres is a brand, not specifically meaning they're racing tyres. They are a track/road tyre and they're very good for reference.

 

1) unlikley.

 

2) No, but he does increase his chances of a lowside by doing so.

 

3) No, there is race lap time performance to be had by doing this, braking later into the turn and carrying more into the turn, but also see point 2. He wouldn't (well shouldn't), be braking all the way through the turn, that's completely uneccesary, you either brake, or use the throttle, not both to my mind.

 

4)Yes, that's right, the application of throttle does transfer the weight, though you can (and I don't reccomend it any beginner/moderate level), to brake into the turns (see point 2). What in essence happens, is the rider leverages the exceptional grip levels of the modern tyres and gets away with it. and thus thinks its something you can/should do.#

 

The reality if using the brakes with the bike leaned over is possible, though if you look at top level riders, as they increase lean angle, the brake lever pressure decreases. So lots of brake straight upright, and release pressure from turn point into the turn. How far you can go into the turn depends on the type of turn, how the bike is setup, the grip you have and so on. Reccomended. Not until it's really becoming your limiting factor to going really fast, No.

 

Bullet

 

 

Ok, I am with you on the tire question. It's a trade name, not a race tire.

 

And now for some other clarifications. I can be anal at times, don't take it as me being cheeky. ;)

 

 

1) Which is unlikely? Riding to the limits or mimicking the pros?

 

3) I understand braking later will help lap times. He is dong this throughout the turn.

 

no problem, the devil is in the detail.

 

1) limits, am sure your friend is trying to mimic the pros.

2) braking later doesn't neccesrily help laptimes, its carrying extra speed into the turn and only getting to your mid corner speed as late as possible. so, the gap between brakes and gas is minimal. if your friend is indeed braking all the way through the turn, that's unneccesary for sure, into the first part of the turn perhaps some time to be had, though so is the risk of a crash. I would clarify with your friend how long in and through he's braking, though I still wouldn't reccomend it at inter level.

 

Bullet

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Did you watch some of the onboard shots during the German GP, where they show the throttle hand? These riders are either braking or accelerating, hardly ever are they coasting.

 

 

+1

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