Emergency stop practice - gear change problem

[robertvi]

Being a noob I've been practising emergency stops on some back roads near my house. This type of stop obviously dispenses with engine breaking and down shifting, so when I come to a stop I'm in 4th gear with the clutch in. Now when I try to shift down into first to pull away again, the gear selector lights just go blank, and the leaver feels like it's not shifting properly, like it's stuck in limbo somewhere around gear 3-and-a-half.

Sometimes, after struggling with the shifter for a while, it suddenly seems to find the gears again. Other times I've stopped the engine and restarted, or pulled away in 2nd because it won't go all the way down to first. It's a 2006 Suzuki GN250. Any words of wisdom?

(PS I already tried pulling away in 4th guess I wasn't pushing it fast enough).

[robertvi]

sudden "brain wave": do I need to wheel the bike backwards to fix this?

[TimeOut]

sudden "brain wave": do I need to wheel the bike backwards to fix this?

Yep, moving back and forward will help. Bike gearboxes are sequential not like cars
Try to change down while still moving, if it's real bad try shutting the bike off and rock it with the clutch engaged.

Don't apply too much force to the gear leaver as that can do damage.

[CookMySock]

90% of your sudden braking is completed 50% into the manoevre, so you get time to sort the gears out. The small percentage of the time (microscopic) where you are forced to a stop in a high gear is an inconvenience you will just have to reconcile.

Steve

[scracha]

Being a noob I've been practising emergency stops on some back roads near my house. This type of stop obviously dispenses with engine breaking and down shifting

Why "obviously". Yes, the most important thing is getting to a stop safely and quickly. However, You should also keep your fingers off the clutch lever to take advantage of engine braking (also keeps the bike a bit more stable) and in a perfect world pull it in at the last minute and bang it down the gears.

In "real life" you'll shit your pants, lock up both wheels, come to a stop in 6th and stall the engine LOL. Make sure you check what's around you after a real life emergency stop and if necessary push the bike or simply get off it and run like fuck. I can't stress this last point enough; you may have spotted the hazard and pulled a beautiful emergency stopp(ie) but the myoptic 4x4 driver up your arse might not be so perceptive.

Getting it back in gear. Wot Timeout said was spot on.

See the "braking" thread where I'm correct, and most of the other posters are not (sic). I think there was something on the Wiki but the oversealous Nazi Mods erased it.
http://www.kiwibiker.co.nz/forums/sh...107722-Braking
http://www.kiwibiker.co.nz/forums/sh...rgency-Braking

[robertvi]

Thanks! I'll try rocking it back and forth next time if I'm stuck again. And good to know that engine breaking can still be of some use in this situation.

[slofox]

This type of stop obviously dispenses with engine breaking and down shifting, .

No it doesn't. Well, not for me anyway. I find that I downshift whilst braking during an emergency stop without even thinking about it. I must have learned to do this centuries ago 'cause it always happens. I prefer to use every bit of braking available in an emergency stop. Which includes engine braking.

[cowboyz]

actually.. me too. In any emergency stopping I find myself flicking through the gears by default before I even start braking. Then its all over the front and remmebering there is a rear in there somewhere. I drive on the gearbox alot anyhow. (and yet I dont seem to find the urge to rev the shite out of my bike on a downshift)..

[sleemanj]

Clutch when emergency braking, two schools of thought, first is that not clutching will allow you to use the engine to brake the whole time, second is that not clutching won't allow you to downshift easily so your engine braking is limited to whatever gear you are in. Engine braking contributes little to an emergency stop anyway I expect so either way, just make sure you are on the brakes.

Changing gear when you've stopped in a high one, you'll get the hang of it, but just use the clutch to "click" it into gear, hard to explain since it's a bit instinctual, but with clutch in, put pressure on the gear shift like you're trying to change, and slightly release the clutch, it should click in, a slight rock back/forward may help if it's stubborn. Without the engine running, rocking is required.

Also occasionally you might hit a false neutral when shifting up if you don't quite catch the gear, usually in front of a load of people as you try for that uber cool take off, also pretty normal, bike gearboxes are finicky beasts.

[Mom]

Being a single pot engine the GN actually has reasonably good engine braking, infact is is really easy to compression lock the rear wheel if you drop it into 1st and let the clutch go quickly. Good fun if you are just turning into your driveway but can be disasterous if you manage to do it around a corner. I would encourage you to start to practise engine braking in conjunction with your (hopefully) progressive emergency braking. Anything that is going to slow you down faster has got to be good.

[slofox]

Engine braking contributes little to an emergency stop anyway

Mmmm...it sure feels like it does to me. Got any links regarding this at all? Might be interesting to compare stoppping distances with and without change-downs. Must try it one day...

[p.dath]

Lets just say that emergency braking technique is highly contentious, and there is considerable disagreement over the use of things like the clutch.

Personally, I feel the answer depends on the speed you are commencing the emergency braking manoeuvre from. I present for your consideration this study:
http://www.fmq.qc.ca/pdf/amorce-freinage_eng.pdf

Emergency braking on the track from high speed is very different from emergency braking on the road from 100km/h, because of how quickly the weight shifts from the rear to the front tyre.

My personal opinion, if you are emergency braking from 100km/h or less, engage the clutch. Forget engine braking. Engage the rear brake, shortly followed by the front brake. The study above explains it well.

If you were doing it from 200km/h on the other hand, I'd tell you to forget the rear brake altogether. Because the load transfers so fast onto the front wheel that only the front brake is effective. For this same reason I feel that engine braking has a limited impact (remember, this is emergency braking). Once the weight has come off the back wheel then using the back wheel to slow down the bike has little impact.
On the track engine braking may be used more - but that is because you want drive out of the corner, and not just achieve maximum stopping power. On the track you only want to effect a rapid decrease in speed, but never to a speed of zero.

I now sit back and put on my flame suit.

EDIT: Upon reflection, I think engine braking into a corner on the track is more involved. I think it has some impact to overall speed, but I think it has more uses than just speed alone. But I still hold that I think engine braking is of limited use when braking from 100km/h on the road in an emergency situation.

[slofox]

is really easy to compression lock the rear wheel

Yeah. I've done that under emergency braking as well...

[Mom]

Yeah. I've done that under emergency braking as well...

I remember doing it for the first time on a GN. I was following my lovely man, he decided to turn off the highway at VERY short notice. I was barrelling along and had to um...
slow down quickly so I could make the turn and not overshoot and have to travel a kilometre up the road before I could safely turn around. The rear wheel locked and went all sorts of sideways Shit oh dear! It had been so long since that had happened to me.

After that, I used to deliberately lock the rear wheel as I started to turn into our driveway

You dont get too much fun on a GN, you have to take every opportunity it presents

[Tryhard]

Engage the rear brake, shortly followed by the front brake.



The rear first? is that for real?
I think I maybe practising the wrong way!