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Old 05-03-2013, 03:27 PM   #16
AzItLies
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Originally Posted by Andyvh1959 View Post
I teach the MSF BRC and ERC, in which we do stress maximizing traction by separating cornering from braking actions. For noobs and riders not experienced enough to really use trail-braking it is just easier. In fact, its enough work in many cases just to get riders to believe/trust how much traction and lean angle capability bikes have.

But trail-braking is a very effective technique that I use sometimes. Used right it helps maintain a smooth pace through the twisties. Often though, I'm able to set my entry speed on my BMW R1100RS using downshifting and powering through the turn. The Telelever has very little front end dive during braking so the turn-in attitude of bike changes little with braking applied.

But it is surprising how many riders have no idea what trail-braking really is. I had a MSF student once tell me, "watch me in corners because I do a lot of trail braking." Ok I said, but I asked him to describe what he meant by trail braking. He described it as only dragging the rear brake into the turn. He said nothing about applying both brakes while downshifting to the turn apex, and then applying throttle while blending off the brakes from the apex to the exit.
My understanding is yer 'trailing off' the brakes from entry to apex, then throttling on from apex to exit.

Both in the ART and Freddie Spencer indicate Trail Braking can be just the front, just the rear, or both. Personally, I like both.

The unfortunate misunderstanding is from the name "Trail", and thus many associate it with dragging the rear brake (as one would do riding trails).

Really scary part of just using the rear, as noted by the above mentioned, sliding the rear may very well result in a high side... could do really serious damage...

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Old 05-03-2013, 03:51 PM   #17
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I expected it too. Where are they?
They crashed cause they won't trail brake. They'll post tomorrow...
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Old 05-03-2013, 05:08 PM   #18
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I was reading something, I believe by Keith Code, where he hinted that trail braking was the less expert technique vs. braking upright prior to the turn. I thought about it and it kind of makes sense: If you do all your braking while upright, prior to leaning into a turn, your have to exactly, expertly, gauge your entry speed and basically throw away opportunities to adjust your speed. Kind of a gamble if the road throws something your way like gravel, a corner that decreases quicker that you thought is would, etc.

Maybe he was just being thought provoking but it did make me think about trail braking vs. getting all my braking done before the turn.

Oh, and btw, I trail brake while street riding.
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Old 05-03-2013, 05:38 PM   #19
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Originally Posted by sloperut View Post
I was reading something, I believe by Keith Code, where he hinted that trail braking was the less expert technique vs. braking upright prior to the turn. I thought about it and it kind of makes sense: If you do all your braking while upright, prior to leaning into a turn, your have to exactly, expertly, gauge your entry speed and basically throw away opportunities to adjust your speed. Kind of a gamble if the road throws something your way like gravel, a corner that decreases quicker that you thought is would, etc.

Maybe he was just being thought provoking but it did make me think about trail braking vs. getting all my braking done before the turn.

Oh, and btw, I trail brake while street riding.
That really depends on the corner doesn't it? Flick vs trailbraking

I find it very difficult to find a corner I can take safely that allows me to carry enough speed to trailbrake effectively(street)

shaddix screwed with this post 05-03-2013 at 06:16 PM
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Old 05-03-2013, 05:52 PM   #20
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How much traction does a tire have, and how much is available for cornering traction vs. braking traction?

Take a look at a Kamm's Circle diagram.


A good street tire on dry pavement might have 1.0g of traction. A race tire maybe 1.2g. A good street tire on wet pavement maybe 0.8g--a smaller circle on the diagram. On frost...maybe 0.2g--tiny circle.

The amount of total traction available is the vector sum of the braking (or acceleration) traction and cornering traction. If you look at the yellow lines above, it looks like he may be using 0.6g acceleration (but braking works the same way) and maybe 0.7g cornering traction, but the vector total is 1.0g--nothing left behind and nothing in excess to cause a slide.

The very skilled rider will use close to the full available traction at all points around the circle. The less skilled but careful rider will have a diagram that looks like a four pointed star. The higher skilled rider with have a fat four point star. The hot dog will have worn sliders on his bike.
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Old 05-03-2013, 06:34 PM   #21
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The amount of total traction available is the vector sum of the braking (or acceleration) traction and cornering traction. If you look at the yellow lines above, it looks like he may be using 0.6g acceleration (but braking works the same way) and maybe 0.7g cornering traction, but the vector total is 1.0g--nothing left behind and nothing in excess to cause a slide.
Where can I read more about this, because it is counterintuitive. I have read this elsewhere, and despite MSF coaches assertions that if you are leaned over 20 degrees the brakes are unavailable, I have messed around with a pretty significant amount of brakes at 30 degrees+ and didn't feel anything out of the ordinary.
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Old 05-03-2013, 07:21 PM   #22
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Originally Posted by shaddix View Post
Where can I read more about this, because it is counterintuitive. I have read this elsewhere, and despite MSF coaches assertions that if you are leaned over 20 degrees the brakes are unavailable, I have messed around with a pretty significant amount of brakes at 30 degrees+ and didn't feel anything out of the ordinary.
The friction circle is something I haven't seen expressed in that clear a format. MSF has used the Traction Pie in the past (I don't know if they still do) but, like the Traction Circle, has never put any information in terms of degrees. No credible training organization would tell someone a degree to lean to because it too difficult to calculate on the fly.
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Old 05-03-2013, 07:33 PM   #23
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The friction circle is something I haven't seen expressed in that clear a format. MSF has used the Traction Pie in the past (I don't know if they still do) but, like the Traction Circle, has never put any information in terms of degrees. No credible training organization would tell someone a degree to lean to because it too difficult to calculate on the fly.
Lean angle is proportional to lateral acceleration. If you know one you can easily get the other

So that circle for example if you have .6 of one and .7 of another you aren't at 1.3 as far as losing traction goes. But does it "feel" like 1.3? Would an accelerometer show 1.3?
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Old 05-03-2013, 07:42 PM   #24
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I am past the noob stage and somewhere in between knowing what I am doing, having only owning two different bikes I have noticed a huge difference in how to manage them through a turn. But I have learned early on that using the front bike in the middle of a turn is not always best and started using the rear brake a lot more often, even on Honda Shadow that I had using the front brake was not good because of too much front end dive. On my current bike (FZ6R) the engine has a lot more engine compression and down shifting a gear or 2 before a turn and power through seems to be working fine for me.

Also as somebody stated about noob's "Just grabbing the front brake". One bit of advice I give to brand new riders is that sometimes the best thing to do is nothing at all. For example one morning I was heading in to work a leaning into a turn and I hit a patch of frost and I knew if I did anything it would go from bad to worst, so I just easily backed off the throttle til I had the bike in the upright position.

Panic braking is a serious flaw in many drivers and riders experiences.
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Old 05-03-2013, 07:59 PM   #25
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I think the panic grab is an under estimated in its contribution to overall crashing.
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Old 05-03-2013, 09:00 PM   #26
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Quote:
Originally Posted by shaddix View Post
Lean angle is proportional to lateral acceleration. If you know one you can easily get the other

So that circle for example if you have .6 of one and .7 of another you aren't at 1.3 as far as losing traction goes. But does it "feel" like 1.3? Would an accelerometer show 1.3?
Its just a graphic representation. Its all about balance really. You have 100% traction, you can use it for what you need to. Braking, accelerating, or turning.

Basically pick two.

The big advantage to trail braking is that the you don't have to unsettle the front end with tip-in. When I learned it they called it "zizzing" you basically keep the front end from unloading between braking for a corner and apex, after apex it doesn't matter because you are back on the throttle.

Trailing also makes the bike tip over faster, so a lot of guys will load the front end for fast left-rights at the track.
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Old 05-03-2013, 10:12 PM   #27
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I practice a bit on trail braking here and there, but the only corners on my commute are at stoplights so it's not like I get a lot of chances :P Certainly is a valid manuever, though I separate it from "braking in the corner" for everday situations. It's still a benefit for everyday riding as it helps to keep the chasis stable in a corner and better primed for unexpected situations.

For Basic Rider Courses, I'm with the MSF in emphasizing getting your braking done before the corner. A new rider already has enough for their mind to actively focus on, so as others have mentioned, it's best to separate braking, cornering, and acceleration. I do, however, believe they should implement some lessons on gradual braking in the corner. The last time I spoke to an instructor (2011?), they were teaching to stand the bike up in the corner, brake, then lean the bike back once you were done braking. More instruction on gentle front brake use (even outside of a corner) could probably do a lot to prevent panic grabs. EDIT: This could vary from instructor to instructor -- I didn't look at the actual cirriculum or anything, so this is anecdotal.

Trail braking should be taught in something like the ARC and the like. By then, a rider should have enough experience to smoothly transition between throttle and brake while managing a corner entry. And it does have some practical use in everday riding. But it is a more advanced technique.

Regardless, keeping things universal and simple for a baseline is best, in my opinion. Most riders (in the US) do so as a hobby, let alone take an ARC or track program, so splitting cornering into very distinctive steps helps them to retain some skills and minimize the things that can go wrong.
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Old 05-03-2013, 10:18 PM   #28
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I have no idea where the term "trailing" came from (and I should know that). It's used to describe the distance from the entrance of the turn to the apex. For example, new Porsche drivers are often caught (by the weeds) when they experience trailing throttle oversteer for the first time - the tendency of a RWD car to kick out its rear end when throttled into a turn. Interestingly enough, the safest way to overcome this is to continue to roll on the throttle very very slowly, to avoid the worse condition of lift-throttle oversteer.

In bikes, these are the equivalents of backing it in and highsiding.

The progression in skill/speed is brake then turn to trailbrake/downshift/throttle to just ignoring the brakes and using the throttle for everything.

The easiest way to begin to understand this is to work on downhill turns, where you can just use the throttle for everything!
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Old 05-04-2013, 05:21 AM   #29
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I have a very hard time believing that people are finding a requirement to trail brake on the street. Either you're riding like a complete idiot, or you're trail-braking just for fun. There's really no in-between.
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Old 05-04-2013, 06:20 AM   #30
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Come and ride in the mountains of Italy. Terribly steep and littered with switchback and decreasing radius turns. You too will understand trail braking.
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