"Weaving under braking or emergency stop" thread in "Staying Alive"
I've been out today practising the counter leaning technique that Spin taught me at the weekend, and decided to have a go at some emergency ...

I've been out today practising the counter leaning technique that Spin taught me at the weekend, and decided to have a go at some emergency stops whilst I had free reign of a large car park.

Most of these went OK, but on a couple I started to get a really nasty weave under max braking. I didn't have to back off the brakes much, but it felt that if I'd not reduced braking effort the front would have tucked or slapped.

I've noticed this a couple of times before whilst track riding and having the anchors out hard for hairpins.

Is this mostly down to locked/tense arms putting steering action into the bars during the stop, or are there other factors that can affect this?

Thanks in advance!

Are you experiencing a front end weave or the sensation of the rear of the bike moving around under heavy braking?? Locked arms will exaggerate any feeling and you will of course be unloading the rear as the weight transfer effect takes hold....bracing your knees onto the tank will help avoid all the weight going onto your arms...

Have you checked things like head bearings too as if these are not adjusted properly or are worn they may contribute to the sensation you are describing?

Suspension set up may be part of the issue too but am sure Spin will offer some comment if he knows your bike and riding style....

TBH I'm not totally sure; I'd say it felt more like the back of the bike moving...or it seemed to start that way and "amplify" into something "quicker" at the front.

I'm not sure if that makes it any clearer!

When you're braking so hard the back wheel lifts, it feels like the rear of the bike's waving around all over the place.

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Formerly known as Mikey

Possibly it's the back of the bike is on the verge of getting airborne, although it could be a quirk of the machine. They've got fairly soft forks as standard (I assume you were on the Fazer??) and I suppose you could be bottoming them. I've not ridden either the Fazer 1000 or the CBF500, so not really sure tho.

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"Force has no place where there is need of skill" Herodotus 450BC

I'm still pootling about on the CBF500 spin, whilst I get my slow control together properly.

Gonna look in the garage now to see where the oil marks on the forks are, I cleaned the bike after Saturday so whatever's there now is because of this afternoon...

Yup, forks well and truly bottomed out, LOL.

Serious question: is it worth holding the effort and going for the rolling stoppie just so that I've got a reference point for when to back off in a real emergency? Is it normal for the bike to feel so squirrely or have I got my weight distribution wrong if it feels like it's weaving?

On my head be it, literally, of course

If the forks bottoming, you risk locking up the front when braking over bumps. Try a little more preload and/or compression damping to reduce weight transfer to the front.

Why are there oil marks on the forks these should be dry?? If they are leaking then this will be contributing to your problem and there is little point in trying to alter the settings until you have them sorted IMHO If they are not leaking but are bottoming out then you do need to tweak the settings... if you are not sure then I would take them to somebody who knows how to deal with this issue...

Certainly wouldnt be trying to practice a stoppie until you are settled in your mind as to cause of your weave!!

Tyre pressure?

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Safe riding.
MrGnome (formerly known as NC30Gnome).

Riverside Motorcycles, Sunbury on Thames, 01932 787535
UP THE IRONS! www.ironmaiden.com

Maybe he oiled the exposed part of the forks for protection against the winter weather and he's able to see how far up they get cleaned under heavy braking.

Isnt that a good way of attracting dirt to the fork legs which then damages the seals ? Using a cable tie is much better way of measuring fork travel....

The thing that really ****s your fork seals is rust and pits in the chrome, so preventing that has always been my top priority.

What I always did when despatching was to cover the fork legs in a heavy "underwater application" grease. The dust cap "swept" the grease off the bit of the slider that disappeared into the fork leg. With that technique I've never had a problem with rust, I've actually worn the chrome thin on one set of sliders so they did start seeping and replacement seals didn't cure the problem.

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The dull copyright bit - feel free to nick it for personal use. If you want to reprint it for your club, I'd like a mention as author. Otherwise hands-off. Full terms
"Force has no place where there is need of skill" Herodotus 450BC

That's the one BB; I went a bit over the top with the old ACF50, so I was able to see where the forks had been up to.

I checked them this morning, and the front was 2 psi below where it should have been, so I guess that wont have helped.

I got this bike recently from a reputable dealer, so it should have had things like the head and swinging arm bearings checked before I collected it. If I notice any more strange goings on I might run it past my local spanner-wielders for a proper going over.

Thanks for the extra thoughts though; I think I'll take one of my other bikes out to the same place and see if I get different behaviours.

I don't think the CBF500 had adjustable front sussies, but I'll give the cable tie idea a go and see where that ends up during normal riding. I'm planning on holding onto this bike for a while so it might be worth having a proper suspension set up.

I'm usually pretty confident on the brakes though, so some of this might just be down to hauling on the anchors hard. I had to ease off a couple yesterday 'cause I could hear and feel the front starting to "chirrup"

Edited to add: I was also accelerating hard through 1st and 2nd before doing the stop; I must have been a bit too cack handed on some of the runs by not letting the bike settle down enough before braking. Throwing all the weight from one end of the bike to the other wouldn't have helped

I wouldn't know. Mine are either fully enclosed like Roadholders, have gaiters on, or are girders.

See, I can be quite perceptive when I want to be.