BGOL

[Graham Wright]

As a newbie, would someone please explain the limits of validity for avoiding it.

Obviously, approaching traffic lights you need to declutch before the engine stalls and then, declutch, handbrake, and neutral. (Perhaps someone could also explain why handbrake, declutch. If you have approached in, say, third gear, like wot I was told, you cannot pull off in that gear if the situation changes).

Even approaching a corner, it seems to me (as a newbie) that not overlapping pedalling, is going to lead to jerky motion.

[jont]

<gets popcorn>

we've done this a few times

Without really trying:
/viewtopic.php?t=113
/viewtopic.php?t=62
/viewtopic.php?t=1552

/waits for Gareth to provide better links

[GJD]

What's the context - how have you come upon the idea of BGOL avoidance? Has it come up in the course of RoSPA/IAM training - if so, what's your tutor/observer told you? Have they described some benefits you may find you experience if you practice the technique?

What do you mean by jerky? RoSPA and IAM examiners generally value smoothness and that can certainly be achieved when separating braking and gear changing. You can come onto the brakes smoothly, you can come off the brakes smoothly and you can change gear smoothly. But you do have to give yourself enough time to do it all, so you might need to start braking sooner than you currently do and/or brake more firmly than you currently do.

[Graham Wright]

I first made acquaintance with the topic on this forum and no, I was not taught the technique nor appraised of its advantages during my IAM tuition.

Having decided I need to make a gear change, my body performs the evolution almost without my mental assistance (and, I am told, my gear changes are exemplary!).

Thus, alternating between clutch and brake pedal, seems to introduce an intermittent delay which I have described as "jerky". But my main problem of comprehension is understanding the claimed advantages. Approaching a point where braking and gear change are required, what is gained?

I approach a turn requiring a reduction in speed (again my braking is described as "smooth"!), I will brake to the correct speed for the manoeuvre, and then change gear in order to accelerate after it.
Brake, down gear, brake, down gear etc. seems to offer no advantages. Indeed it could be regarded as increasing transmission wear and even suggest the use of "engine braking" horror horror!

I am warming to this now! I think a graph of speed v time using the sequential change-down technique could be very interesting with zero speed change sectors at every gear change. This, albeit minor, would not equate perfectly to "smooth".

However, I am here to be educated and await clarification with eager anticipation!

[GJD]

There are kind of two facets to this. One is that the preparation for the hazard involves a single gear change, from whatever gear you were in before to whatever gear you're going to use to drive through the hazard. The other is that that gear change happens after braking is complete. Which aspect are you asking about - perhaps both?

[Graham Wright]

Ok, my comprehension is improving, but, if I am approaching a turn in top gear, is there not a risk of the engine labouring as the revs drop to the correct corner negotiating speed before changing down to, say, first?

[GJD]

Ok, my comprehension is improving, but, if I am approaching a turn in top gear, is there not a risk of the engine labouring as the revs drop to the correct corner negotiating speed before changing down to, say, first?

Yes, and that's easily handled by declutching before braking is complete.

I think people sometimes distinguish between 'full separation', where you don't declutch until braking is complete and 'partial separation', where you (have to) declutch during braking but all the rest of the actions for the gear change wait until braking is complete. With a large reduction in speed, full separation might not be possible, and my understanding is that partial separation in such a situation is compliant with IAM/RoSPA/Roadcraft style driving.

[Graham Wright]

I'll go with partial separation (nice to see it spelled correctly!).

I guess that is what I do anyway. If you change down before the speed is correct to negotiate the turn, then you would be in "engine braking" which is punishable by death I understand!

Thanks for the education.

[jont]

I guess that is what I do anyway. If you change down before the speed is correct to negotiate the turn, then you would be in "engine braking" which is punishable by death I understand!

Not if you heel and toe to rev-match while braking. But that's another can of worms

[onlinegenie]

I'll go with partial separation (nice to see it spelled correctly!).

Yes it is!

I guess that is what I do anyway. If you change down before the speed is correct to negotiate the turn, then you would be in "engine braking" which is punishable by death I understand!

Is it? ISTR that when I trained in 1983 I was advised to change down to third gear when going downhill as this would result in engine braking that would help me to keep to a legal speed. Was my observer wrong? (In which case I've given bad advice to an awful lot of people over the years!)

[michael769]

Is it? ISTR that when I trained in 1983 I was advised to change down to third gear when going downhill as this would result in engine braking that would help me to keep to a legal speed. Was my observer wrong? (In which case I've given bad advice to an awful lot of people over the years!)

No. There is a difference between selecting a gear to help you maintain your control of your vehicle's speed, and changing gear in order to reduce the speed of the car.

In the case of the slope you are controlling the vehicle's speed via the accelerator the lower gear is simply the tool that facilitates that. This is often best practice on long slopes for many reasons.

Terms like engine braking and "no BGOL" can sometimes cause confusion sometimes as the word brake is overloaded, on one hand it refers to the act of braking on the other the act of slowing down. It's the act of slowing down that is the no-no, not the act of braking.

[TR4ffic]

In Roadcraft, BGOL is mentioned/OK in relation to turning left or right off the main carriageway into a side road - employed so as not to potentially confuse other drivers waiting at the junction in to thinking you are giving way/giving priority to them by an early brake/reduction in speed to fit in full separation.

Depressing the clutch whilst under braking when coming to a halt (traffic lights, junction, queue, etc.) to prevent a stall. I don't class that as BGOL.

If you need to partially separate when on the open road, for a sharp bend perhaps, where you have to reduce speed to such an extent that you need to depress the clutch to prevent a stall/engine labouring in your current gear, you need to have completed braking and foot off the brake, and selected the correct gear for your road speed, before lifting the clutch - with rev match as required.

...is there not a risk of the engine labouring as the revs drop to the correct corner negotiating speed before changing down to, say, first?

If you have any forward motion, then 2nd gear should be fine. First only if you come to a complete standstill.

I'll go with partial separation (nice to see it spelled correctly!).

That will be spelt then...

[Graham Wright]

I'll go with partial separation (nice to see it spelled correctly!).

That will be spelt then...

Them wot nos bessed allow both spelling!

[waremark]

I first made acquaintance with the topic on this forum and no, I was not taught the technique nor appraised of its advantages during my IAM tuition.

...

I approach a turn requiring a reduction in speed (again my braking is described as "smooth"!), I will brake to the correct speed for the manoeuvre, and then change gear in order to accelerate after it.

I think that describes exactly the approach recommended by IAM and Rospa. If it did not come up during test preparation with an Observer, the reason is probably that you were already doing it the way he wanted to see.

The offence which is 'punishable by death' is changing down while still braking in a way which causes the engine revs to be dragged up significantly when you raise the clutch - clutch braking, rather than engine braking. Ideally, IAM and Rospa examiners do not want to see the clutch being raised without your right foot on the accelerator except in a couple of specific situations, and then only right at the end of braking when road speed is low enough for the engine revs not to be dragged up far. They also want to see both hands stay on the wheel until the road speed is low. (Away from IAM and Rospa tests, other driving experts have different views, including the famed H & T).

Are you still in doubt about the benefits of separation after looking at the linked threads?

[Graham Wright]

Are you still in doubt about the benefits of separation after looking at the linked threads?

Yes! I understand "what" and "how" and "when" but I can't find "why".

Decelerating for a turn, braking and engaging the appropriate gear for exit from the turn, would seem to save time without any obvious dangers and maintain progress.
I can appreciate that turning the wheel at the same time as a gear change is obviously a no no.