Brake Bleeding Stromer ST5/3


Well-Known Member
So lately I had the need for bleeding brakes on my Stromer St5 which should also be similar for Stromer St3.

The brakes are custom built by TRP. They are 4 piston brakes with great stopping power however since they are customized it may be a bit confusing to figure out how to bleed them.

Fortunately it is pretty easy. Here is what I used:

1. A simple brake bleed kit with a catch bottle
I used a kit like this one :

2. Brake Fluid. It uses mineral oil. I used TRP specific one (Tektro is the same)however people used Shimano mineral oil on trp/tektro brakes with success.


3. IPA and some towels/clothes to clean things up.

Overall the process is very similar to the following guide by TRP the main difference is instead of a bleed cup we use a catch bottle.


1. Take the wheel off

2. Take the brake pads out and put plastic brake blocks in place.

The method is pretty simple. The Bleed port on these brakes are on the side.

1. Fill the syringe with brake fluid(I would say at least 3/4 of the tube should be filled) and make sure to get rid of the air inside. Keep the syringe upside down so that remaining bubbles float away from the tip.

2. Remove the plastip cap from the bleed nipple. Plug the syringe to the nipple.

3. Turn on(loosen) the bleed nut at the caliper. I used an adjustable wrench for this one, its size is around 6mm.

4. push the second silicon tube all the way in the catch bottle.

5. Remove the bleed port screw(you will need a torx key). Be careful there is a seal on the screw don't lose it. screw the adapter in the port and connect the other side of the tube that is coming from the catch bottle.

6. Push the fluid from the syringe to the system. Keep pushing until the fluid going to the catch bottle no longer has any bubbles in it. If the fluid is dirty keep pushing until it runs clear, discard the dirty fluid, refill the syringe (careful about the caliper bleed nut make sure it is closed when removing the syringe) and repeat.

7. At this stage pull the brake lever several times, it should be quite firm. This also helps removing the bubbles. If not push some more fluid from the syringe and see if new bubbles are coming out.

8. Turn off the bleed nut at the caliper, remove the syringe. Remove the silicon tube from the brake lever bleed port, put the screw back on. I usually make it finger tight but not too much.

9. Since my the oil in the catch bottle was clear I saved it for re-use in the future.

*While I levelled the brake lever as can be seen from the pictures, I doubt it is necessary since the bleed port screw is on the side.

Here are a couple of pictures that should make how the connections should be clear.

caliperSyringe.jpg catchbottle.jpg

Before reinstalling the brake pads clean everything with IPA to make sure that nothing is contaminated with mineral oil.

Best of luck.
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Well-Known Member
only a few things put the syringe tube on before opening the port you need a little wrench for it if it is like shimano a 7 mm you want to get the lever as level as you can turning the bike with the front up helps. usually I loosen lever so I can rotate it till it is level. when do before taking the cup off flick the lever a bunch of times to remove any air you don't want to squeeze it till you have replaced the seal and locked the port. then test it. I like having a cup that screws onto the port on the lever as you can put fluid into it to keep air out