Scooter braking guidance - and this applies to all scooters, whether fitted with combined braking systems, ABS, or both:
1: Normally, Front Brake first. Simple physics dictates the first thing to is load the front contact patch as the rotational torque tends to want to rotate the chassis around the front wheel spindle. So, front brake first. I don't care what Bosch say, unless they've changed Newtonian Physics using software.
2: As soon as the front brake is beginning to be applied, apply a modest amount of rear brake. If rear brake applied first as Bosch suggest, there is an increased tendency for the bike to `skate` rather than load the front end, and braking efficiency reduces by around 20%. This is still safe, right up to the point where the 20% loss of efficiency crosses either the distance available, or forces a late increase in braking effort causing a lock-up. In either case you crash or at the very least need a visit to the underwear shop, so:
3: Increase front brake until desired level of retardation is attained.
To use this, we adopt a simple practice technique known as the `four finger shuffle`.
Instead of wrapping all fingers around the front brake lever, and squeezing with all four, you apply one at a time, beginning with the index finger, then adding the next, and so on. This has the useful effect of modulating the braking effort, reducing the tendency to `snatch` at the brake and incite a skid or lock-up. Co-incidentally it will also be the case that in the majority of instances you will never get to the pinkie!
Sports scooters with demon brakes will normally only need a finger or two, but you do NOT, EVER use a system where you wrap the last two fingers around the grip of the handlebar. Trap those fingers with a brake lever and you will prevent full application, or tie the hand to the throttle so that you cant close it properly. Professional racers do this because they are professionals, and racing.
We, are not.
Now where this really pays off is with ABS. The electrickery enables you pull past the `Oh Frack` factor - fear of pulling the lever is greater than the fear of the impact. It is actually a sad statistic that in most cases the accident occurs NOT because the scooter or motorcycle is over-braked, but because despite the onset of a scooter: vehicle interface the brakes are not applied sufficiently, or well.
ABS allows the rider to have more confidence in adding the pinkie to the squeeze and really increasing the pull.
Now as I mentioned, in such an emergency situation you WILL be right in the heart of the 20% so if the technique is not correct, neither will the maximum braking capacity capable of being added. ABS will not save you. But with this technique there is only one technique to learn, and apply consistently.
For this reason two things need to be practiced regularly every time you ride, perhaps even while sitting on the bike in the garage making `Brrm, Brrm` noises...
1: Applying the brakes right/left/right or front/rear/more front, to be pedantically correct
2: Applying the four finger shuffle
After that there is one key piece of advice - LEARN your ABS - you must find a safe area where you can really take the braking to the limit. As I said, fear is by far a bigger braking limitation than brakes, machine OR ABS. Best practice you will ever do is go to a quiet car park on a pissing-down Sunday afternoon and amaze yourself how hard you can actually brake in the wet, on a scooter.
This is more complicated to explain than put into practice!
Oh and it does NOT cater for
all braking contingencies, but for very practical reasons this is what you learn first, best and well.
We can talk about back brake as a tool for tight manoeuvres and slow-speed control at another time, or as a high speed instability eliminator, how you can use fork dip to enhance turn-in or back-brake first under some circumstances to allow for a harder initial application of the front brake by reducing weight transfer and fork dive, but ONLY in the intermediate and advanced classes. For now, learn to do this, and do it well.
Finally, to save The CBS questions - the above technique will, ON ALL Combined Braking Systems, also work well - in fact it may be even better as the consistent pull on the back brake can still result in a small level of increased retardation from the back brake, by being linked to increasing pressure on the front.
Finally, the physics. Total braking capacity is affected by just three things:
1: The total power in the brakes (in most modern cases that will comfortable exceed anything you will ever need on the road. Classic Vespa and Lammie owners can, however, nod at this point at what they are missing...)
2: The total coefficient of friction available through the tyres. Grippier tyres can brake harder, two tyres can brake harder than one (a fundamentally lost awareness in bike racing circles, as you can almost double braking effect by NOT having the excessive weight transfer of a high headstock design and single, loaded front tyre)
3: The ability of the rider to take advantage of the first two, not just with braking skill, but with riding skill that means you never test the limits of 1 and 2.
So it matters not a jot if you have ABS, CBS, USB or HIV, if you aren't well-versed in 3, 1 and 2 will be no use to you whatsoever.
No door is closed to an open mind.
Except a closed door, which a mind can't open, but even a stupid hand can.
) will disagree. 
