Front Brakes Triumph Bonneville
"Improved brakes" means different things to different riders. Brakes are optimized for a variety of factors, and the weight of each factor depends on the operating conditions.
For a racer, it is important that the brake retains its functionality when heated up for a long time. They use ergonomic adjustment in real time, allowing you to adjust the position of the lever. Complex ventilated calipers, brake rotors, and titanium cylinders are installed on motorcycles. All this is expensive and has no effect in civilian use. The master cylinder ratio is also chosen to work best under continuous load, even if it isn’t optimal for a single stop.
For a stunt rider, it is important to easily brake with one finger (hand brake), therefore, a big ratio of the master cylinder is selected. The handbrake reacts even to a light touch, but the brake doesn't work when overheated.
For an enduro rider, it is important that the brake remains operable when heavily contaminated. Performance is not as important, because a bad grip of the wheel limits the ability of any brake. This allows you to use a simple, reliable, and cheap system.
For a street rider, the brake should provide a minimum braking distance during single braking, and a rather high ratio is desirable so as not to put too much pressure on the wrist while riding. System operation under continuous load is not as relevant as it is for professionals.
The braking system effectiveness is limited by the grip of the tyres, the geometry of the motorcycle and the stability of the suspension.
A sport bike has a short base and an upright fork — during braking almost the entire load falls on the front wheel. Therefore, an effective fork is used, which steadily presses the wheel against the road, and wide tyres, which allow greater contact with the surface. This configuration allows more powerful front brakes, because the wheel cannot lock up — the more you brake, the stronger the wheel is pressed against the road, and the higher the friction force is.
Enduro and motocross motorcycles are equipped with long-stroke soft suspension, which allows riders to jump and navigate obstacles. Such suspension cannot steadily press down the front wheel when braking. Motorcycles of this class also have narrow off-road tires with little surface contact, so there is no point in installing stronger front brakes — they would easily lock the wheel and add a lot of weight.
On choppers and cruisers with a long base and a raked-out fork, when braking, the front wheel is loaded less. The front brakes are weaker than on sportbikes and roadbikes, despite the large difference in weight. Plus the suspension is adapted for a comfortable ride. On such a motorcycle, it makes no sense to use multi-piston calipers and two discs, which we would not be able to use at their full potential, and which could lock the front wheel at the slightest deterioration of the traction.
Triumph Bonneville is one of the most popular models for customizers, largely due to the base and geometry. The base of the motorcycle is not very long, so with a slight decrease in fork offset, wheels and suspension replacement, it is possible to achieve intensive and strong loading on the front wheel to make full use of powerful front brakes. Good projects based on Bonneville have powerful front brakes that are not only an accessory, but also a fully functioning system.
The standard brake system on the Triumph Bonneville is optimized well for the overall configuration of the bike. But the motorcycle itself is technically obsolete, and does not correspond to modern conditions of operation. Simply put: it accelerates much faster than the traffic around it but can’t stop as well; on a twisty road you have to slow down a lot, holding up traffic, because there is no feeling of stable grip when leaned over. In its standard version, the motorcycle is not urban, but suburban.
The cheapest way to upgrade the front brakes is a floating disc of a bigger diameter and a caliper with a larger piston area (the 4-piston Brembo 30/34 and 6-piston SPIEGLER/ABM work well). But without a fork upgrade this setup will not be significantly more efficient.
In this video, we showed a simple way to install a non-standard caliper: using an aluminum adapter. The standard brake hose is a bit short, but in our case an aftermarket braided hose was already fitted. As a result, we can say that such a system is good in terms of price / quality ratio. The dual disc brake, which we did on our SXRacer project, works better, but requires a whole range of complex, expensive modifications.