There is nothing worse then spongy brakes that pull right to the bar in my opinion or brake levers that just don’t feel as firm as they should. But have no fear as there is a quick easy fix that I like to use on all my bikes to keep the brakes feeling nice and crisp. First of all though we need to know why the brake lever feel has deteriorated, micro air bubbles are usually what is to blame. These small air bubbles for in the brake fluid and over time they eventually form into larger pockets of air that hinders the effectiveness of the brake fluid, causing a spongy feel. Another issue is old brake fluid that is dirty and full of dust particles and other nasty stuff that you do not want in your brake lines, for that I recommend a brake flush. By draining all the old fluid and adding new stuff it will make the brake feel a lot better then you can do minor adjustments to fine tune the brakes feel with the tip that I will be discussing. I will be discussing the various steps I take to make my Shimano brakes feel better, this works with other makes and models though some steps might be different.
Make sure the bike is on a level surface and you have some approved brake fluid for your make of brake that you are going to be working on. Clean the brake lever and make sure your work area is clean.
Adjust the brake lever angle to make the bleed screw level, this avoids any fluid from dripping out and allows you to fill the reservoir to the top and eliminate all the air in the system.
Once level, remove the brake reservoir screw. Sometimes this take more effort then you would think as the o-ring seals in tightly and often has never been removed.
After removing the screw you will see inside the reservoir, if fluid is all the way to the top then there most likely no air in the system, however if you see empty space then this tip will help.
Take you approve fluid and top up the reservoir, using a brake bleed kit will help with this, Shimano has a bleed cup that screws into where the reservoir screw came from.
Once full you can work the lever in slowly to push fluid into the system and as a result you should see air bubbles coming up and escaping from the system.
Repeat step 6 over and over till the air has been eliminated from the system, you can try taping the brake, brake line and caliper to help the air move through the system.
Remove bleed cup if you used one, ensure that brake fluid is full and re-screw the reservoir screw, often fluid will be pushed out while you screw this back in and that’s fine, just wipe it away.
Test the feel of the brake, it should feel better, firmer and not go down to the bar. If the lever doesn’t feel good repeat the process and see if more air is in the system.
This tip works for small tweaks to get the brake lever feeling better, it will not be a replacement for basic brake maintenance and a LBS is recommended if you have brake issues. Be sure to use the right fluid!
A quick side not that most customers don’t know… Usually any self work or issues from doing self work voids warranty unless for a qualified LBS mechanic. TBS Bike Parts takes no liability from doing this tip.
Purchase the following products here…
Shimano Bleed Kit
Shimano Olive and BarbsShimano Brakes and RotorsShimano Mineral Oil
Written by Cody Decker – Head Product Specialist at TBS Bike Parts