| |||||||||||||||||||
| | On the road Scooter braking systems: as sophisticated as in cars By T. Groussin Scooter manufacturers are focusing on braking and are increasingly offering assistance systems, such as linked braking and ABS, on their vehicles. So you can begin and enjoy two-wheeling in the best conditions!  Braking is one of the trickiest aspects of two-wheeling to get to grips with. In an emergency it is, in effect, a matter of applying sufficient power on the brakes to stop in time, whilst remaining below the limit beyond which the braked wheel will begin to skid. In a car, a wheel that skids in this way no longer performs its steering function and the vehicle consequently becomes uncontrollable. On a motorcycle or scooter, locking the front wheel under the effect of overly pronounced braking is even more harmful, since the gyroscopic effect stabilising the vehicle suddenly stops, almost inevitably resulting in a fall. Locking of the rear wheel is of less consequence, since you simply have to release the brake for the two-wheeler to return to its axis by itself. It is not at all surprising, under these circumstances, that loss of control of a two-wheeler occurs essentially during braking (in over 40% of cases, source: ACEM). Knowing how to brake therefore means considerably reducing the risks of an accident. Without assistance, it's just down to experience Classic scooter braking leaves the rider to handle the front brake (controlled by the right-hand lever) and the rear brake (left-hand lever) independently. In theory, the power of effective and safe braking must be distributed 60% at the front and 40% at the rear. In principle, the different configuration of the front and rear brakes (notably a bigger disc at the front) means that you don't have to worry too much about that when using the two levers equally. On the other hand, the onus is on the rider alone to work out the limit not to cross in order to avoid the dreaded locking of the front wheel. Progressive and easily controllable equipment makes things easier, but nothing beats a few practice sessions in a deserted car park to familiarise yourself with the reactions of your braking system. We also recommend using just two fingers to brake at the front, which makes it possible to measure the power more accurately than with four. Moreover, we advise you to keep these two fingers permanently on the lever in order to gain precious seconds in an emergency. Combined braking system: lightening the load Many scooters are now equipped with a braking system dubbed combined (or linked or integral), which means that you no longer have to worry about the distribution of brake force between the two wheels. In effect, in this case, the left-hand lever simultaneously controls the rear brake and the front brake, with optimal distribution of power between the two wheels. But beware: when braking in an emergency, this system does not dispense with having to call upon the right-hand lever, which for its part controls only the front brake. However, even in this case, the work of the automatic distributor considerably reduces the locking limits. Scooters equipped with this type of equipment are not only to be found in the top of the range. The Piaggio X9, one of the most luxurious 125 cc models, is of course equipped with it, but so is the Honda 125 SHi, which is £800 less expensive. Two types of technology are currently used by manufacturers to offer combined braking.  Two types of technology are currently used by manufacturers to offer combined braking. The most simple and economical is to connect the two brake levers by a cable, so that a touch on the left-hand lever acts simultaneously on the right-hand lever (without the right-hand lever interacting on the left). The disadvantage of this system is that the rider feels the interactions of the two levers, and therefore has to get used to it. Another more sophisticated solution consists of connecting the left-hand lever to the front and rear brakes by a hydraulic system. In this case, in addition to its action on the rear brake, the left-hand lever acts simultaneously on one of the pistons of the front calliper (Honda system) or on one of the two front discs (Piaggio system). These two systems are equally pleasant to use.
Now ABS, even on 125 cc models! As for motorcycles, an increasing number of scooters are equipped with ABS anti-lock systems. In the maxi scooter segment it is becoming common. In the 125 cc scooter segment only BMW (with the C1, production of which has been stopped) and Peugeot (with the Elystar and soon the Satelis) have taken up this approach for the time being.  The interest of ABS is of course to prevent any wheel lock when braking and consequently any loss of control in these conditions. But beware: this system is in no way intended to reduce braking distances. On the contrary, it is possible that they may be increased, especially if the tyre-suspension set-up is not capable of sufficiently repelling the wheel lock limits and therefore the triggering of ABS pressure modulation. ABS can of course be associated with a combined braking system (Honda Forza 250 EX for example). The most sophisticated system is currently offered by the German company FTE (www.fte.de) which notably equips the Peugeot Elystar and forthcoming Satelis. The rider of such a scooter benefits from three types of assistance: automatic distribution of brake force between the two wheels, the ABS system, and an electronic amplification of power which increases the muscular force exerted on the levers (Powered Braking System). In short, exactly the type of braking that is to be found in cars.
Photographies: © Piaggio, Vespa, Honda | ||||||||||||||||||