Low Speed Turns and Using the Friction Zone

[wildbears]

Two videos on the same topic. With one the U-turn is initiated while riding parallel and close to the curb. And the other starts the turn away from and towards the curb.

https://www.youtube.com/watch?v=apzllVdtfXc

https://www.youtube.com/watch?v=j1Pjc-Y8K3k

[wildbears]

A "Friction Zone" can also be used on a bicycle when doing tight U-turns. It would seem that feathering the back brake rather than the front would be preferable.

Clarification: As a bicycle does not have a clutch to modulate power output, braking while pedaling to provide power to the rear wheel creates a brake "Friction Zone" for better control. (Note the quotation marks.) IOW, the brake provides friction to modulate power output.

Technically, this is termed trail braking on a motorcycle. However, with motorcycles the term can be used with or without power input to the rear wheel. For example when doing a low speed turn to modulate power output or when leaned over in a turn at speed without power output.

Trail braking at speed affects the suspension of the motorcycle (absent on a road bicycle but present on a mountain bike).

"It is used beyond the entrance to a turn (turn-in), and then gradually released (trailed off)."

The brakes are completely released at some point in the turn based on the turn dynamics.

"If the motorcycle is leaned over, forces from the front brake and the deceleration cause the motorcycle to yaw (lean), while use of the rear brake generates a torque that tends to align (straighten) and stabilize the motorcycle."

Use of the front and back brakes together would settle the suspension to provide more steering control.

Cossalter, Vittore (2006). Motorcycle Dynamics (2nd ed.). Lulu. ISBN 978-1-4303-0861-4.

Please comment if you have other insights or opinions.

[bertbrumfield]

Friction zone has nothing to do with the brakes, - but slipping the clutch to maintain controlled power to the rear wheel.

And you definitely want to use only the rear brake in slow tight turns, never the front, as it could skid and slide out. NOT a good thing.

Front brake for maximum stopping. Rear brake for low speed control.

[wildbears]

Good points for motorcycling, Bert.

[Flyboy]

Want practice on trail breaking, run a few European passes

[955i]

Did a bunch of trail braking this week bombing down gravel roads and single-track on bicycles in and above Crested Butte, Colorado! Fun stuff!

[wildbears]

Here's another video on using the friction zone for tight low speed turns on a motorcycle:

https://www.youtube.com/watch?v=5xbI9TOcVI4

And more from the same instructor on trail braking for tight low speed turns on a motorcycle:

https://www.youtube.com/watch?v=0ZqxbHISEBo:

The above are parts of a 5 part series on tight low speed motorcycle turns that include counter balancing and full handlebar lock techniques.

[wildbears]

So, does using the friction zone technique add a component of gyroscopic stabilization at low speed?

[bertbrumfield]

????? ????

[wildbears]

The question revolves around whether an ICE creates gyroscopic forces due to rotation of the internal parts. Consider that use of the friction zone technique for low speed turns uses an engine speed that is higher than required for moving the motorcycle.

[Pittsdriverwes]

I'm going to say no. There's nothing about operating the clutch in the friction zone that adds any gyroscopic - just having the engine running at all does that and would be the same if you did your U turn with the clutch pulled all the way in or in "the zone." You really shouldn't be putting too many revs on the engine in the friction zone to be kind to your clutch. Barely above idle while feathering the clutch to control your speed is the ticket! Or that's how it's taught at the BMW Performance Center in SC.

[wildbears]

And does panic use of the rear brake in a turn at speed, cause a motorcycle to stand up and go wide?

[bertbrumfield]

If by panic braking, you mean locking and skidding the rear wheel,
AND if "at speed" means more than 20-25 mph,
in a turn,
will probably cause a "low side" or sliding the bike out from under you, not standing up.
People who don't know how to ride often call this: "laying the bike down"

[wildbears]

There was a rear wheel lock up and low side in the Tour of Spain this season. Roglic broke away and was speeding thru a fast downhill curve.

[wildbears]

Let's consider sub-lock-up braking forces.

[wildbears]

Then for bicyclists riding trails, does trail braking refer to use of the rear brake to change direction quickly.

And is the front brake used mainly to scrub off speed and not considered trail braking?

[bertbrumfield]

Then for bicyclists riding trails, does trail braking refer to use of the rear brake to change direction quickly.
locking the rear wheel to slide the rear around will change directions [tighten the turn] quickly on a bike or mc. this only applies off road or off pavement [which is not so forgiving].

And is the front brake used mainly to scrub off speed and not considered trail braking?
The front brake is used to slow and stop the mc in a straight line and has nothing to do with "trail braking"

Are we mixing motorcycles and bicycles??
the friction zone technique does not apply to bicycles, - only to the use of the clutch.

[wildbears]

Thanks for you thoughts.

[justjoe]

A lot of people have bad information in regards to trail braking. Watch this video, it discusses trail braking in detail.