Murray Walker talks about Wobble and Weave on Motorbikes

[Motofool]

Long but good explanation by retired Formula One commentator and journalist for those riders that like letting both hands off the handle bar:

Copied from another thread:

.........When taking for a test ride i was coasting and like i normally do let my hands off the bars and stretched and the front wheel started to wobble very violently. I've had it for eight months and do that all the time and that has never happened.

Link to original page on YouTube.

Even when a violent wobble doesn't make you fall, it could disable your front brake temporarily:

Link to original page on YouTube.

[csmith12]

I can confirm a tank slapper at 100+ can kill your front brake. After having some in 2012 and even more head shake than I could shake a stick at. I lost or only had partial front brake about 10% of the time and then you have to pump them back up. I am so glad I am not afraid to use the rear and not panic.

I soooooo need a damper on my R6, no clue why they don't come stock with one.

Nice couple of vids Hernan.

[allanoue]

I did not know about weave but then I have not logged much mileage over 85 mph, still if it does happen I think now I will be less likely to panic.

[Alex]

Originally Posted by csmith12

I soooooo need a damper on my R6, no clue why they don't come stock with one.

You're doing trackdays on an R6 without a damper?

Go get your credit card and click here.

[csmith12]

I will gladly pay you next Tuesday.....

[Alex]

Orthopedic surgery is more expensive.

[bdavison]

It annoys me to no end that the current crop of 600's don't come with dampeners.

[csmith12]

Originally Posted by Alex

Orthopedic surgery is more expensive.

Agreed, been there, done that.

[lgk]

would ABS brakes recover faster after a tankslapper?

[Alex]

I don't think it would matter. The reasons the brakes fail after a slapper is that the pads get knocked back into the caliper from the violent shaking of the wheel. Squeezing the lever the first time there's no braking force as the pads are moved back closer to the disk, and hopefully it doesn't take more than a squeeze or two before they are back in position and able to provide braking force.

AFAIK, ABS brakes don't automatically pump up the pads to the disk surface any differently than normal brakes. They just release the growing brake pressure if the wheel speed sensors / control unit determine that the brake is liable to lock if pressure isn't released.

[Motofool]

Originally Posted by Alex

.......AFAIK, ABS brakes don't automatically pump up the pads to the disk surface any differently than normal brakes. They just release the growing brake pressure if the wheel speed sensors / control unit determine that the brake is liable to lock if pressure isn't released.

I agree; interesting question: the pump is only powered by your hand / foot: there is no dedicated electric pump in ABS's.

ABS only limits over-pressure when the tire is skidding (rotating slower than it should for the linear speed of the bike).

Copied from
http://en.wikipedia.org/wiki/Anti-lo...stem#Operation

"Typically ABS includes a central electronic control unit (ECU), four wheel speed sensors, and at least two hydraulic valves within the brake hydraulics. The ECU constantly monitors the rotational speed of each wheel; if it detects a wheel rotating significantly slower than the others, a condition indicative of impending wheel lock, it actuates the valves to reduce hydraulic pressure to the brake at the affected wheel, thus reducing the braking force on that wheel; the wheel then turns faster. Conversely, if the ECU detects a wheel turning significantly faster than the others, brake hydraulic pressure to the wheel is increased so the braking force is reapplied, slowing down the wheel. This process is repeated continuously and can be detected by the driver via brake pedal pulsation. Some anti-lock systems can apply or release braking pressure 15 times per second."

[csmith12]

After a year of track days with some slappers and head shake every time... I have found nothing that helps recover from them aside of just not fighting the bike in any way, shape or form. Which means stay loose on the bars, don't make any sudden shifts in body weight/position, don't chop throttle, grab a handful of front brake or stomp the rear brake. Time and time again it has worked itself out, although I don't think it will work itself out 100% of the time before the bike tosses the rider or we run out of road surface.

When I have little to no front brake, I instantly go for the rear. Get things under control and pump it back up in a straight. Anything else takes to much time and space.

[Panda]

Originally Posted by csmith12

When I have little to no front brake, I instantly go for the rear. Get things under control and pump it back up in a straight. Anything else takes to much time and space.

So by pump you mean you just squeeze, release, squeeze, release, until you start getting brake feel back?

[csmith12]

Warning.... Not for new riders.

Oh! One more thing to add here. You can "somewhat" turn while slapping. As shown in the video, that riders slapper happens on corner exit and he continues the exit even while shaking pretty good.

Most of mine occurred just after a crest where the front gets light or lifts off the ground. When it touches down out of alignment (SR ), you get instant head shake or a full blown slapper with an approaching right turn. Turn 10a at Mid-Ohio sets this crest/corner condition up every lap.

I have found that if your really, really commit to it, using the hook turn you can turn a bike while the head is shaking. It's scary as hell... but beats crashing. Never give up.

[csmith12]

Originally Posted by rPanda

So by pump you mean you just squeeze, release, squeeze, release, until you start getting brake feel back?

Yep, exactly. And you get to scare yourself again when going into the next corner wondering if you pumped them enough to set entry speed.

[Panda]

Originally Posted by csmith12

Which means stay loose on the bars, don't make any sudden shifts in body weight/position, don't chop throttle, grab a handful of front brake or stomp the rear brake.

Staying loose on the bars seems and keeping control inputs neutral seems to be the answer to a lot of issues ie. head shake, front end getting loose, rear end sliding, etc.

Is there ever any reason you should get tight on the bars?

[csmith12]

Sure, everyone has seen MX riders. They snatch and grab all the time. Or, if you have ever taken a street bike off the smooth road surface, depending on terrain a tighter grip may be preferred.

For example; You can't let larger rocks, large sticks, ect... determine your steering.


Skippii here has the hard line on this one.

Link to original page on YouTube.

[Panda]

Cool, thanks for posting the vid. I haven't ever ridden off road on a bike yet. Maybe this year I'll take one of the off road courses offered by PA.