Steel-braided brake hoses for motorcycles
Improved braking performance, better braking control: steel-braided brake hoses are one of the most advisable improvements you can possibly make to your motorcycle – irrespective of whether your interest lies in shaving milliseconds off your lap times on a circuit or in riding more safely on the open road.
Why choose braided steel rather than rubber?
What at first glance looks like a thinner version of a shower hose is actually a steel-braided Teflon brake line which – unlike many stock rubber hoses – will not expand under the pressure created when you apply the brakes. This makes the braking action far more responsive and provides a precise pressure point that you can feel through the brake lever. Steel-braided lines are also resistant to ageing, unlike their rubber counterparts, which tend to become porous after around 5 years and need replacing. So now is definitely the time to switch to steel-braided brake hoses – for enhanced safety, and also because they look a whole lot better!
Key essentials for any work on your braking system are a good degree of experience, absolute safety awareness and a clean workplace. So if this is your first time, it's really important to get the help of a professional.
When changing the brake hoses, you will be working with brake fluid, so you should be aware that brake fluids DOT 3, 4 and 5.1 are corrosive and damage paintwork. Any splashes must be immediately washed off with plenty of water. DOT 5 is silicone-based and not corrosive. Always check your vehicle manufacturer's specifications before buying brake fluid (operating instructions / inscription on main brake cylinder). Also carefully read the safety instructions on the packaging prior to use. Old brake fluid and any cloths used must be disposed of correctly at a collection point for hazardous waste!
Changing brake hoses – step-by-step instructions
Drain braking system
Before suctioning off the brake fluid, place cloths over any parts of your motorbike at risk of damage, like the mudguard. It's also a good idea to wrap a cloth around the reservoir to soak up any splashes. Use the correct size of screwdriver to undo the generally very soft screws in the cap of the reservoir and place the cap on a lint-free cloth. You can now draw off the brake fluid in the reservoir. If you don't have a suction device, you will have to wait a little longer before the next step is complete, or pump with the brake lever.
Now remove the brake line at its lowest point (brake caliper) and place it in an acid-resistant container in order to drain the system. You can speed up this process by pumping the brake lever. If your bike is fitted with two brake calipers (dual disc braking system), you will need to repeat this step on the second brake hose.
When you're quite sure that the system is empty, unscrew the first hose at the top end and compare it to the new brake hose. Important: The old hose must be handled carefully. Brake fluid is aggressive and any brake fluid remaining in the hose could attack painted or plastic parts.
Fit steel-braided lines
Once you have cleaned the contact surfaces, you can fit the new brake hose and new seals. Always make sure the hose is not twisted and has no kinks. Route the brake hoses exactly the same way as the old ones so that they do not rub or kink when the forks compress. Always make sure to tighten and torque all connections to the specifications of the motorcycle or brake hose manufacturer. Anyone who thinks a torque wrench is just for amateurs should think again! Brake caliper and main brake cylinder casings are very delicate parts, so overtightening can cause fractures and hairline cracking. And they're not exactly the cheapest parts to replace. If you're the lucky owner of a bike with dual disc brakes, you can now repeat this last step with the second, and possibly the shorter, upper line running from the main brake cylinder to the distributor pipe.
When you've done all that, prime (refill) and bleed the braking system. Due to the smaller inside diameter of the steel-braided lines, bleeding them isn't always entirely simple, and without a brake bleeder it may take you quite a while, or you may not succeed at all. We therefore strongly recommend using a proper bleeding device like the Mityvac brake bleeder. But if you are reluctant to splash out – good luck!
Prime (refill) and bleed brake lines
The following is a general step-by-step guide, as each bleeding device comes with its own specific set of operating instructions.
Fill the reservoir with new brake fluid up to the Max. marking as specified by the manufacturer (see above). Grip the bleed screw with a box-end wrench, attach a transparent hose to the valve and place an acid-resistant container under the hose. Undo the bleed screw by a half-turn. Pump the brake lever/pedal 3 times. Keep the lever depressed and close the bleed screw again. Then release the lever. Keeping an eye on the "MAX/ MIN" levels in the reservoir, repeat this procedure until you can no longer see any air bubbles in the transparent hose. Lightly tapping the hose and the distributor with the handle of a screwdriver can help to expel the air from the system. Do not at any point allow the brake fluid to fall below the "MIN" level in the reservoir – keep it topped up! Once again, if your bike has dual disc brakes, repeat this last step. If a brake caliper has two bleed screws, you will need to carry out the bleeding process twice. If, despite numerous attempts, the brake lever/pedal still feels spongy after you close the bleed screw, this may mean there is a leak in the system, or you opened the bleed screw too far, or you need to use a special bleeding device because air is trapped in the system and will not shift. If bleeding was successful, you can now top up the brake fluid reservoir to the "MAX" level and replace the rubber sleeve and cap. ALWAYS carry out a final stationary check to ensure the brakes are functioning properly before riding your bike. The brake lever should travel a short distance and then have a good solid feel. And so – happy braking ...
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The Louis Technical Centre
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These tips for DIY mechanics contain general recommendations that may not apply to all vehicles or all individual components. As local conditions may vary considerably, we are unable to guarantee the correctness of information in these tips for DIY mechanics.
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