Stopping quickly from high speed/high gear

[Sossige]

I had to stop quickly on approach to a set of traffic lights this morning - no drama, but was wondering about something that happened.

I was braking and whilst doing so, heard several clicking noises from what sounded like the gearbox. I can't see that the bike was slipping into neutral as I later had to downshift through the box when stationary - and it certainly didn't stall as I pulled the clutch in when the revs dipped low enough.

Normally I would downshift through the box and benefit from engine braking, but that was something my instructors ironed out of me during my DAS; they were of the opinion that the examiner would want to see maximum braking and not disengaging drive by bringing the clutch in to change gears.

Any ideas what might have been going on? I guess I shall find a long quiet road and see if I can work out what was happening.

S

Edited by Sossige on Wednesday 30th July 15:20

[Rick448]

Could have been the chain chattering as you braked hard. I'd also agree that in a hard sudden braking situation you should just brake, if you get the downshift wrong it can lock the rear and make it unstable.

[Sossige]

Thanks Rick - the chain is lubed well, so is chain chatter something that would be normal in that kind of situation? I checked the chain slack recently so I know it's nothing sinister involving the chain and swingarm

[B15TT0]

Was it your nuts knocking against the tank?

Common problem when braking very hard!

[Aubrey]

Does sound like it could have been the chain chattering. This can happen under heavy braking as the front is slowing faster then the rear, i.e. the rear wheel is still travelling faster than the front which can cause this chatter. I've had it happen occasionally. I also change down the gears as I'm braking.

I'm not sure I agree with the instructor about not using maximum braking power by changing down the gears. Watch the bike racing and you'll see them changing down through the gears as they brake for a corner. You have to go down through the gears so you are ready to move again, especially if you're not bringing the bike to a halt and just braking for a corner. The brakes have the most stopping power. Not changing gears will not help braking, if anything it will have a negative effect. If you're changing down the gears then you will have maximum engine braking too. HTH.

[black-k1]

Not sure what the noise was although I’d be surprised if it’s the clutch slipping. (unless you have a slipper clutch!)

I would suggest that downshifting through the gears is a good idea as you are braking from high speed (remembering to blip the throttle as you go) even in quick braking events. The only thing to watch is that there is a slightly increased risk of rear wheel lock up when the clutch is pulled in to allow the downshift. The increased engine braking provided by the lower gear should more than make up for the reduction in engine braking while the clutch is pulled in, especially on multi cylinder engines.

[Rick448]

Aubrey said:

Does sound like it could have been the chain chattering. This can happen under heavy braking as the front is slowing faster then the rear, i.e. the rear wheel is still travelling faster than the front which can cause this chatter. I've had it happen occasionally. I also change down the gears as I'm braking.

I'm not sure I agree with the instructor about not using maximum braking power by changing down the gears. Watch the bike racing and you'll see them changing down through the gears as they brake for a corner. You have to go down through the gears so you are ready to move again, especially if you're not bringing the bike to a halt and just braking for a corner. The brakes have the most stopping power. Not changing gears will not help braking, if anything it will have a negative effect. If you're changing down the gears then you will have maximum engine braking too. HTH.

I would say that in normal practice changing down as you brake for a turn is required.. or as you quite rightly say you will not be in the correct gear to accelerate out of it. In an emergency or unexpected braking event i would go with brakes only as it is easy to panic and stamp down the gears and upset stability at the point you need it most. Yes racers do change down but the engine braking effect is minimal compared to the actual brakes, and even less so with the use of slipper clutches which are there to stop the rear locking and destabilising the bike. What is the saying.. erm brakes to slow, gears to go!

[C8PPO]

black-k1 said:

(unless you have a slipper clutch!)

Well that's what I was wondering?

[Rick448]

I think he has a Hornet 600 which don't have one as far as i am aware..

[Chilli]

Depends on the situation realy. If it's a serious one, I'd grab as much front as I dare, stamp on the rear, and be back in first before you could say, sh.....

[hornetrider]

Chilli said:

Depends on the situation realy. If it's a serious one, I'd grab as much front as I dare, stamp on the rear, and be back in first before you could say, sh.....

Do you really stamp on the rear? Maybe that's why you are au fait with so many hedgerows.



My Falco rear brake is utterly gash, so it never gets used. Really, never.

[Aubrey]

Rick448 said:

Yes racers do change down but the engine braking effect is minimal compared to the actual brakes.

Agreed. I think it all boils down to experience. A good rider should not panic, and should have the presence of mind in an emergency to change down the gears as well as hard braking. You have to think, well if I'm doing an emergency stop, then something could well be coming up behind me, so you should be in first gear asap so you can move again if need be.

Each to his own though. I also use the back brake when heavy braking, I find it helps stabilise the rear and keep it in check.

Edited by Aubrey on Wednesday 30th July 12:11

[Rick448]

Aubrey said:

Rick448 said:

Yes racers do change down but the engine braking effect is minimal compared to the actual brakes.

Agreed. I think it all boils down to experience. A good rider should not panic, and should have the presence of mind in an emergency to change down the gears as well as hard braking. Each to his own though. I also use the back brake when heavy braking, I find it help stabilise the rear and keep it in check.

I agree that a good rider shouldn't panic, however i am sure there have been moments when a situation becomes far worse than you think and not through your own actions, my take on it is that i would rather use my attention on braking and or steering around a situation than worrying about being in the correct gear to accelerate away from it afterwards, as there may not be an afterwards!

But as you rightly say each to their own and there are no hard and fast rules, what works for one may not work for another.

[black-k1]

hornetrider said:

My Falco rear brake is utterly gash, so it never gets used. Really, never.

You should always use the back brake. If it's utterly gash, get it looked at.

[EvoBarry]

I would go with chain chatter too, its just slapping the guides a little as the rear wheel speed is slowing down too much. My tip, learn to use more front brake. I barely touch the rear brake generally, using it for stabilising the rear at most.

[dern]

Your lock and chain isn't under the seat is it? I worried about a bizare engine noise for a while and was completely unable to reproduce it on the drive and it turned out to be the lock and chain under the seat rattling

[GreenV8S]

EvoBarry said:

II barely touch the rear brake generally, using it for stabilising the rear at most.

I'm not a biker so excuse me if this is a daft question, but how does the rear brake stabilise the rear? Is it in terms of stopping rear end lift?

Sometimes in the context of cars people talk about the rear brakes as if they dragged the rear of the vehicle back into line preventing it from stepping out, but this is a complete nonesense.

[black-k1]

GreenV8S said:

EvoBarry said:

II barely touch the rear brake generally, using it for stabilising the rear at most.

I'm not a biker so excuse me if this is a daft question, but how does the rear brake stabilise the rear? Is it in terms of stopping rear end lift?

Sometimes in the context of cars people talk about the rear brakes as if they dragged the rear of the vehicle back into line preventing it from stepping out, but this is a complete nonesense.

In the same way that applying the front brake causes the front to dip and the rear to rise, applying the rear brake causes the rear to squat, slightly compressing the rear suspension. As the rider comes off the brakes and into the corner, the rear suspension is already slightly loaded giving a more controlled weight transfer from the front wheel to the rear wheel.

[EvoBarry]

As above, it helps in fast sweepers too, you can control the bikes stance easier with a bit of trailing brake than rolling off and pitching the weight forward etc

[Aubrey]

GreenV8S said:

EvoBarry said:

II barely touch the rear brake generally, using it for stabilising the rear at most.

I'm not a biker so excuse me if this is a daft question, but how does the rear brake stabilise the rear? Is it in terms of stopping rear end lift?

Sometimes in the context of cars people talk about the rear brakes as if they dragged the rear of the vehicle back into line preventing it from stepping out, but this is a complete nonesense.

It also can help keep the rear in a straight line. Sometimes, the rear can step to one side under heavy braking. It's called 'backing in' but can only be done by skilled riders/racers going into a corner. It looks good, but is easy to loose. The rear brake can help prevent this.