Nachiket, Author at AllBicycleRider

Over a period of time, the brakes on your bike might undergo wear and tear. You will notice the spongy brakes all of a sudden on a Sunday lunch ride which will make you think- how do you fix spongy brakes on an MTB? Generally, soft or spongy brakes occur because of air trapped in the brake line. These air bubbles slowly increase over time and cause the brakes to be less effective. The air can be removed by performing a simple bleed on the brakes which will help remove the air from the brake line I must caution you at this point that I am not an expert on brakes but only a cycling enthusiast with a lot of experience. If your brakes feel too loose, spongy, or ineffective the best thing to do would be to take your bike to a bike shop and have a mechanic look over the problem. Do not compromise your safety while riding! Steps For Fixing Spongy Brakes on an MTB This method might also work on road bikes with hydraulic brakes (disc brakes) as the braking system is similar #1 Adjust your brake lever First things first- you need to adjust the brake lever so that the brake lever reservoir is at the highest point. The reason?- you guessed it- air travels from low to high when inside a dense liquid. That is why you see water bubbles come up when boiling water, or when you use a spirit level and the bubble always rises to the top. Air is lighter than hydraulic fluid, so when we place the brakes such that the exit point is at the top, we can enable the air to travel up the brake line and exit. #2 Press the brake and unscrew the reservoir Now, press the brake lever and tie a rubber band between the brake lever and the handlebar to keep it in that position. Next, unscrew the screw that opens up the brake fluid reservoir. At this step, you might need some extra brake fluid to top up the brake line. Use a funnel and insert it in the opening of the reservoir and pour some brake fluid into the funnel (note- use your bike's user guide or manual to find out which fluid to use. Only use the correct fluid type. If in doubt consult a bike mechanic). Remove the rubber band that was holding the brake lever. #3 Tap and press the brake lever Once you have done the above, tap the brake lever using the back of a screwdriver or any hard object. This is because we want to shock the system and help remove trapped air. When you press the lever and let go of it quickly (like flicking) the fluid is pushed through the brake line and immediately sucked back which pulls the air bubbles up and out of the line. At this stage, if there is a lot of air in the brake line you should see bubbles coming up from the funnel which is actually quite satisfying to watch. This means that what we are doing is working. Press and release (flick) the brake lever a few times so that all the air trapped inside gets a chance to release #4 Remove the funnel and plug the reservoir hole Once you are happy that all the air has exited the brake line, we can then remove the funnel and screw on the reservoir cap. This might prove a bit tricky and messy to carry out so do make sure that you have cleaning materials and pieces of cloth nearby to clean any mess. If you use bleed kits then for certain companies like Shimano you might find special funnel caps that can screw onto your brake lever. This gives the whole system more stability and also lets you plug the screw hole before you take out the funnel thereby reducing the chance of any new air getting trapped. I would recommend using bleeding kits (like this one on Amazon) that work for your brake type as they don't cost much and are any day cheaper than a visit to a bike shop. #5 Press the brakes a few times Once the screw cap has been reinstalled and the reservoir properly closed, press the brake lever a few times to liven up the brake line. Tap on the calipers, and levers to shock the system and let the fluid flow through the line evenly. #6 Time to test and ride! Clean all areas around the brake and the frame of the bike with a clean cloth. If your MTB is on a tripod stand, run the right wheel by your hand and press the brakes to check if they are working properly. Ride the bike and test the brakes in a safe location before going out for a long ride or riding in traffic. For an in-depth video tutorial watch a youtube video on fixing spongy brakes on your MTB brakes https://www.youtube.com/watch?v=NxxWQ4lFHio&ab_channel=HighCarbRider Burping brakes to release trapped air Frequently Asked Questions (FAQs) Q. How do you diagnose spongy brakes? Brakes that feel soft or spongy upon pressing are the best way to tell if there is air trapped in your brake line. If the brakes are becoming less efficient then it is time to fix the brakes Q. Will air eventually go away in brakes? The short answer is no, the air will not go away eventually in the system. This is because braking systems are pretty advanced in their construction and are sealed end to end. Due to day to day usage, air does find its way into the brake lines but it will not go away on its own. You might have to take it to a bike shop to carry out a bleed or burp the system using the steps mentioned above! Q. How do hydraulic brakes work in an MTB? Hydraulic brakes use a braking fluid to push the braking calipers together to stop the bike. The fluid is filled in the brake line that connects the brake lever to the brake caliper. When the brake lever is pressed, the pistons move inwards pushing the fluid through the wire down to the caliper. This extra pressure pushes the brake calipers together and they press against the disc brakes. This creates friction which reduces the speed of the bike Q. Why do my brakes still feel spongy after bleeding? If your brakes are feeling spongy after bleeding it might be because of a few reasons. Either there must be some error in the steps taken to bleed the brakes which might have let more air in or if the bleeding was done right, the braking fluid might be compromised or contaminated. Contaminated brake fluid causes brakes to not work efficiently and can result in lesser brake power. For learning how to correctly bleed your brakes you can read our step-by-step guide in this article Q. Can you leave your bike out in the rain? Rainwater does have damaging effects on bikes in the long term. Read our article to find out whether you can leave your bike out in the rain here