ADUK Archive

Hello everyone,

I'm probably being a numpty with this and completly missing the point, but I'm currently working my way through motorcycle roadcraft and there is a paragraph in the system of motorcycle control chapter that has baffled me slightly. It's about the 5 phases of the system which are Information, position, speed, gear and accerleration and the bit that has me confused is this.

"The system must be used flexibly in reposonse to actual road conditions, do not follow the sequence rigidly if it is inappropriate for the circumstances.

Surley all these points should be considered when approaching a hazard? and sure enough it says that in the first sentence of the next paragraph.

"The phases of the system cover all the points you need to consider on the approach to a hazard.

Am I missing something here? and what type of circumstances would you come accross that would not require you to access the hazard using the system of control?

Many thanks

Jack

As per driving a car, one example would be if there is a vehicle following close behind, that would be forced to change their speed by your competitively early deceleration. In that case brake gear overlap may be permissible.

I'm sure others will come up with better examples.

Maybe the situation changes so you go back to the beginning again.

If for example you are going round a bend and something previously not visible appears and creates an additional hazard you may have to reconsider your position speed and gear in respect of the new information. This is why in the diagrams Information surrounds everything .

As others have said it's about both situations where phases need to be overlapped (i.e. brake/gear) and/or where you need to re-enter the system as the hazard develops or new hazards appear. Mentally you might think of each stage but skip over it if no action is required.

e.g driving along a busy street
Position - central in lane
Speed - suitable for conditions
Gear - to match speed
Acceleration - gentle to maintain speed
Ball bounces out between parked cars
(Position - no change)
Speed - brake firmly, possibly to a bring vehicle to a stop
Gear - select following brake application
Acceleration - gentle or none, depending on above

I know it's a classic highway code example, but I've tried to show that following the ball bouncing out (new hazard) that you go straight to the SGA, steps rather than re-start at P (assuming I throughout).

kwaka jack wrote: Am I missing something here? and what type of circumstances would you come accross that would not require you to access the hazard using the system of control?

It's not so much 'not' using the system as . . .

kwaka jack wrote: "The system must be used flexibly in reposonse to actual road conditions, do not follow the sequence rigidly if it is inappropriate for the circumstances."

Surley all these points should be considered when approaching a hazard? and sure enough it says that in the first sentence of the next paragraph.

"The phases of the system cover all the points you need to consider on the approach to a hazard."

Consider and hazard are the two key words.

One hazard? Consider those you'll need to use, then implement

An unseen (or unforeseen) hazard mid-way through that consideration or implementation? Then you re-consider each and implement if needed.



What's the simplest consideration and application likely to be? Perhaps leaving a quiet motorway at a slip road? However, there's just one, slower, vehicle ahead in lane 1, signalling 'left' as you approach.

But as you get closer, it continues on past on the main carriageway, indicator still blinking merrily . . .

Here you've actually lost a hazard which had probably influenced your choice of speed and perhaps gear, you may even be starting to plan to pass the vehicle on the slip road.

But with that other driver now leaving the road free and clear for you, you can re-evaluate the situation and possibly even increase speed and cancel your signal.

Horse wrote:

kwaka jack wrote: Am I missing something here? and what type of circumstances would you come accross that would not require you to access the hazard using the system of control?

It's not so much 'not' using the system as . . .

kwaka jack wrote: "The system must be used flexibly in reposonse to actual road conditions, do not follow the sequence rigidly if it is inappropriate for the circumstances."

Surley all these points should be considered when approaching a hazard? and sure enough it says that in the first sentence of the next paragraph.

"The phases of the system cover all the points you need to consider on the approach to a hazard."

Consider and hazard are the two key words.

One hazard? Consider those you'll need to use, then implement

An unseen (or unforeseen) hazard mid-way through that consideration or implementation? Then you re-consider each and implement if needed.



What's the simplest consideration and application likely to be? Perhaps leaving a quiet motorway at a slip road? However, there's just one, slower, vehicle ahead in lane 1, signalling 'left' as you approach.

But as you get closer, it continues on past on the main carriageway, indicator still blinking merrily . . .

Here you've actually lost a hazard which had probably influenced your choice of speed and perhaps gear, you may even be starting to plan to pass the vehicle on the slip road.

But with that other driver now leaving the road free and clear for you, you can re-evaluate the situation and possibly even increase speed and cancel your signal.

Righty o I understand it now cheers

jameslb101 wrote:As per driving a car, one example would be if there is a vehicle following close behind, that would be forced to change their speed by your competitively early deceleration. In that case brake gear overlap may be permissible.

Except that, unlike car driving, riders normally overlap.

Motorcycle_Roadcraft wrote:During the later stages of braking change to the appropriate gear.

Zebedee wrote:

jameslb101 wrote:As per driving a car, one example would be if there is a vehicle following close behind, that would be forced to change their speed by your competitively early deceleration. In that case brake gear overlap may be permissible.

Except that, unlike car driving, riders normally overlap.

Motorcycle_Roadcraft wrote:During the later stages of braking change to the appropriate gear.

Normally?

I wouldn't; it would depend totally on the situation, if getting a shift on then gear selection would tend to be after firm braking and when a suitable speed has been achieved - but probably selecting the gear as I ease of the brakes.

However, the ergonomics of bike controls make bgol much easier.

NB you can't 'block change' on bikes, each gear has to be clicked through like flappy paddle car boxes.

Horse wrote:
NB you can't 'block change' on bikes, each gear has to be clicked through like flappy paddle car boxes.

Strictly speaking it is not block changing as you say we are referring to changing sequentially without releasing the clutch, but




Block changing is much easier to say

I see flexibility in the system as meaning phases can be changed, eg position and speed phases being reversed, from the normal system where rigid adherence would cause a problem. IIRC an example is given in the book by Erik Carlsson and Pat Moss published in the sixties whose title was I think something like the Art and Skill of Driving.