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Trail Braking And Effects On The Suspension


4erramses
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What is the difference on the Suspension when using Trail Braking vs. Finish Braking on the straight and then start to Corner?

What is the ideal Speed of Counter steering, referring to the steering rule of Keith: "Always steer as fast as possible"?

When do you stop to Counter steer with trail braking? "1 Steering Input per Turn"

 

Having some issues here on the 2 different styles of braking.

 

Trail Braking:

  • Braking in Lean angle makes the bike to stand up
  • Braking in Lean angle causes the bike to overload the front tyre or eats the front tyre up
  • You cannot have such late turning Point because you Need more time to lean the bike over? (Good for Race Line, because you Close the door to overtaking?)
  • The Forks create a "nose dive" which allows you to create a smoother turn in for your Suspension
  • "Nose Dive" shortens the wheel base which makes the bike to turn faster

Finish Braking on the Straight and then turn the bike into the Corner:

  • When you finish braking before turning the bike, the forks are on normal Position.
  • When you steer the bike very fast, can you create to much cornering Forces that the fork will bottom and lock the front wheel or create a see-saw movement?

Did I get something wrong here?

 

My Real Question is: When to use which Braking Style for which Purpose? What are the effects on the Bike using those 2 different approaches?

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Whew! That is a lot of questions and might be more info than can easily be communicated here, but I'll take a shot at it and maybe you can ask follow up questions as needed.

 

Trail braking (as you describe it above, meaning carrying some braking through your turn-in and towards the apex) does have the effects you describe above and is most appropriately used when carrying speed INTO the turn is more important than maximizing speed on the EXIT, such as: a wide-entry and/or decreasing radius corner at the end of a fast straight, OR a situation where you want a pass another rider on the entry, or you want to enter a turn on the inside to "close the door" to prevent another rider from passing YOU on entry.

 

Conversely, what you describe as "finish braking on straight" is very useful where EXIT speed is most important, such as the last turn before coming onto a straight, or possibly in a qualifying situation where you want to achieve a best-possible laptime by getting on the gas as quickly as possible in every turn; generally it is easier to 'make up time' on the throttle with more acceleration than it is to try to lower laptimes via harder and later braking. Plus it is a much safer approach, since it can be relatively easy to crash when trying to trail brake up to the limits of traction; for one thing, it fires off a lot of SRs that can result in errors that can lead to a crash (tightening up on the bars, using a little too much brake pressure, etc.)

 

These are, of course, broad generalizations; there are many variations in corner situations (shape of turn, what turns are connected before and after, banking, available traction, etc.), and rider skillset, and quality of equipment (tires, suspension, etc.) that can affect a rider's decisions on what technique to use.

 

As far as what the school teaches, the "finish braking on the straight" technique you describe would be taught so that ideally, you are tapering off the brake right as you are turning in the bike, so that the front forks stay partially compressed as cornering forces take over for braking forces. That avoids the situation where the brakes are released, allowing the forks to extend, then the bike is turned, compressing them again. We want to time the brake release to 'keep the front down' as the cornering forces come into play.

 

The steering rule from Twist II is "Steer as quickly as possible in every turn" and directly underneath there is a description of what is meant by "as quickly as possible" and how that is tailored to the turn. Reference Chapter 16 "Steering" for more info.

 

On a modern sport bike with properly set up suspension in normal working condition and good tires it is unlikely that a rider would turn the bike so hard that it would flex the forks enough to create a see-saw effect, or bottom out the suspension - but Keith does mention in Twist II that it would not be desirable to attempt a quick turn over the top of a big bump, as that could overload the suspension and cause a loss of traction. However, on a very old, heavy bike or one not made for spirited cornering, flexing the forks or even the chassis can happen and it can be an unnerving sensation. :)

 

Sliding the front tire in a quick-turn could be possible in low traction conditions like ice, wet pavement, or gravel, if the bike is leaned over too far for the conditions. (I can't think why the wheel would actually LOCK unless you were on the brakes, though.) An aggressive quick turn would not be appropriate in low traction conditions or on a bike with bad tires or suspension problems.

 

Does that help?

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Different types of turns will require different types of braking...as Hotfoot mentions, the steering requirements for that turn can be the larger factor. Having to take an alternate line (as in passing) can be another factor.

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Whew! That is a lot of questions and might be more info than can easily be communicated here, but I'll take a shot at it and maybe you can ask follow up questions as needed.

 

Trail braking (as you describe it above, meaning carrying some braking through your turn-in and towards the apex) does have the effects you describe above and is most appropriately used when carrying speed INTO the turn is more important than maximizing speed on the EXIT, such as: a wide-entry and/or decreasing radius corner at the end of a fast straight, OR a situation where you want a pass another rider on the entry, or you want to enter a turn on the inside to "close the door" to prevent another rider from passing YOU on entry.

 

Conversely, what you describe as "finish braking on straight" is very useful where EXIT speed is most important, such as the last turn before coming onto a straight, or possibly in a qualifying situation where you want to achieve a best-possible laptime by getting on the gas as quickly as possible in every turn; generally it is easier to 'make up time' on the throttle with more acceleration than it is to try to lower laptimes via harder and later braking. Plus it is a much safer approach, since it can be relatively easy to crash when trying to trail brake up to the limits of traction; for one thing, it fires off a lot of SRs that can result in errors that can lead to a crash (tightening up on the bars, using a little too much brake pressure, etc.)

 

These are, of course, broad generalizations; there are many variations in corner situations (shape of turn, what turns are connected before and after, banking, available traction, etc.), and rider skillset, and quality of equipment (tires, suspension, etc.) that can affect a rider's decisions on what technique to use.

 

As far as what the school teaches, the "finish braking on the straight" technique you describe would be taught so that ideally, you are tapering off the brake right as you are turning in the bike, so that the front forks stay partially compressed as cornering forces take over for braking forces. That avoids the situation where the brakes are released, allowing the forks to extend, then the bike is turned, compressing them again. We want to time the brake release to 'keep the front down' as the cornering forces come into play.

 

The steering rule from Twist II is "Steer as quickly as possible in every turn" and directly underneath there is a description of what is meant by "as quickly as possible" and how that is tailored to the turn. Reference Chapter 16 "Steering" for more info.

 

On a modern sport bike with properly set up suspension in normal working condition and good tires it is unlikely that a rider would turn the bike so hard that it would flex the forks enough to create a see-saw effect, or bottom out the suspension - but Keith does mention in Twist II that it would not be desirable to attempt a quick turn over the top of a big bump, as that could overload the suspension and cause a loss of traction. However, on a very old, heavy bike or one not made for spirited cornering, flexing the forks or even the chassis can happen and it can be an unnerving sensation. :)

 

Sliding the front tire in a quick-turn could be possible in low traction conditions like ice, wet pavement, or gravel, if the bike is leaned over too far for the conditions. (I can't think why the wheel would actually LOCK unless you were on the brakes, though.) An aggressive quick turn would not be appropriate in low traction conditions or on a bike with bad tires or suspension problems.

 

Does that help?

 

Thank you Hotfoot and Cobie for that great Input helps me to understand better and make better Quality decisions when riding. You Mentioned very important and interesting Points.

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You mentioned trail braking "eating up the front tire." Certainly that can happen; is that something you are running into?

 

Last Year on Track it happened a lot of time when I pushed for good lap times or racing.

 

My guess:

  • Not Setting Entry Speed right, entering Corner with too much Speed and drifting off the overspeed with the front tyre.
  • Which causes a lot of unwanted Forces not turning the throttle on early.
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