My first hydraulic brake installation.
The rear line was routed, cut, installed to shifter.
- Used a kit with a syringe to pump mineral oil back up through the brake caliper into a funnel on the shifter.
- 20ml was sent up into the line. I was careful to not have any bubbles in the syringe and tube. Bubbles came up, no more at the end
- Then used the vertical overnight technique, followed by a new funnel bubble check at the shifter. Maybe 2-3 more bubbles came up.
But I still feel the shifter travels too much before it's fully depressed (See video)
Still too spongey? Some air bubbles somewhere in the system?
Hydraulic brake install – stiff enough?
byu/endocalvin inbikewrench
by endocalvin
9 Comments
Still too spongy I would say. You want about half to 2/3rds that travel
Shimano systems usually need a gravity/pump and pressurize then quickly open and close the caliper port and set the lever in different angles kinda bleed. Air gets trapped in the top of the rear caliper and sometimes in parts of the lever.
It’s not as complicated as it sounds. Free to cycle has a good tutorial on YouTube. Otherwise I think the shimano manual is also pretty helpful.
If you are confident you got all of the air out, sometimes I’ll take the mineral filled syringe to the caliper end and put a little pressure on the system and then close the port. Firms them up nicely!
If you have a massage gun, use that on the lines and it’ll get that air moved out of there and then you can bleed
When you do a brake bleed, you want to squeeze the brakes a few times as you push the fluid in. If you don’t, some air bubbles can get trapped.
However, you don’t want to do it too fast or too much, if will foam the bubbles a bit into smaller bubbles that are harder to draw out. Slow consistent squeezes a few times during the process works best.
It’s like anything, You need to make a few mistakes to get good at it.
Everyone has their tricks and tips, but with brakes, the main thing is safety. So don’t take short cuts and make sure you confirm information in manuals or multiple reputable sources to stay safe.
There is too much travel.
2 weeks ago, I just bled Shimano 105. This was my first time. I got a cheap 3rd party generic bleed kit on Amazon. I followed YouTube video from GNC Tech, Park Tools, and this one:
https://youtu.be/eGclavtkoIg?si=7Xe-kRKzVoCOq7TQ
Following this 3rd video, after pushing the old fluid thru, I removed the fluid in the funnel, and added new fluid to the funnel. Then I pumped the brakes, which drew fluid from the funnel, and then push more thru the syringe the bottom.
I am not sure if that made a difference. Result was good.
i fought with this same issue – I’ll explain what fixed it for me.
Standard setup, syringe on bottom, cup on top. I filled the syringe up all the way with fluid, and pushed thru (keeping syringe upright to not allow air bubbles in) until it was about to overfill the cup at the top. Then, I’d pump the brake lever ALOT, moving all the fluid back into the syringe from the cup. I did that 3 or 4 times, filling the cup and pumping repeatedly.
It was perfect after! I’ll be doing this every time now to save the headache.
Make sure when you do the bleed that the caliper is the lowest point in the brake system. Sometimes you need to put the bike in a stand almost vertically… which might be the technique you described but I’d do the whole bleed like that. There’s still air in there somewhere. After, I like to use a rubber mallet starting at the caliper and lightly tap from the caliper all the way up to the lever after the caliper is bled and closed up (funnel still on the lever). Make sure the caliper is the lowest point throughout the entire process.
No bueno
When i was doing the same it took about 5 bleeds to get lever work as intended. I had issue with slow lever return
What i understood with brake bleeding is that sometimes you do same steps, and get different result)))