road bike hydro brake bleed debacle

[eddief]

I can do just about any fix and install on mechanical brake and shifting bike but today when I was installing new carbon bars and GRX Di2 shifters on my Roubaix I was faced with a lot of conscious incompetence. You know, never done this before, what could happen, how long will it take, will I be successful?

It was a long haul but got electronic shifting working fine. Cut hoses and installed new barbs and olives and connected to shifters. Used official Shimano bleed kit and syringed fluid from rear brake caliper through hose and up into the pot screwed into the top of the shifter. Closed the bleed screw on the caliper, reinstalled pads, and took the pot off the top of the shifter.

Then pulled on the brake lever and there was no resistance. My guess is there was air in the line.

If yes, how do you get it out?
If not, what else might it be?

I was using a yellow brake block in place of the pads and it fit in the rear caliper, but I could not get it into the front caliper. What up with that?

No big deal and I took the bike to the LBS as I did not want to start throwing tools. Have not had a bike in a shop in many years but hydro brought me to my knees.

Wondering your inputs?

[soupless]

I can't help you diagnose anything but I can chime in and say I'm new to discs and it's been a curve for sure. Very frustrating at times. Seems like a lot of work when the alternative on my amazing 9100 calipers was spinning a screw for three seconds. Although I've only had the bike for like a month...

This guy makes very detailed videos explaining the ins and outs of Shimano hydraulic discs, including a couple of general troubleshooting videos, and I'll link to one that addressed a problem not dissimilar to yours in the beginning:
https://www.youtube.com/watch?v=TLFdMIS--uo&t=913s


Good luck.

[jwin]

You have to firm up the lever with the pot attached to the brifter to excercise the air out of the master cylinder.

[zzy]

Yup. Sounds like air in the master cylinder. Download a copy of Shimanos service instructions and follow it exactly. It's easy with practice.

[Mikej]

YouTube- you’re welcome 😉

[eddief]

rtfd

BR-R785/RS805
With the brake lever depressed, open
and close the bleed nipple in rapid
succession (for approximately 0.5 seconds
each time) to release any air bubbles
which may be in the brake calipers.
Repeat this procedure about 2 to 3
times.
Then tighten the bleed nipple.
BR-RS785
With the brake lever depressed, open
and close the bleed screw in rapid
succession (for approximately 0.5 seconds
each time) to release any air bubbles
which may be in the brake calipers.
Repeat this procedure about 2 to 3
times.
Then tighten the bleed screw again

[NHAero]

FWIW - I have Shimano hydros on two dropbar bikes, and when I'm setting them up I like to make sure the calipers are as directly below the lever as possible, so I may rotate the whole bike in the stand. When I do that, I rotate the bars in the stem so that the lever is oriented properly. The idea being as vertical of a path for bubbles to rise as possible.

[oldpotatoe]

https://forums.thepaceline.net/showthread.php?t=252850

https://forums.thepaceline.net/showthread.php?t=252859

:eek:

:)

[Elefantino]

I don't know why, but I actually had a dream about bleeding Shimano brakes last night and couldn't get the bubbles out. Honest to goodness nightmare.

[eddief]

and the shop just had to do a standard bleed. so now i now how to do olive and barbs and cut hose but need a real lesson on the bleed process. i've watched all the vids but need to understand the pumping process in order to get pressure in the system by working the levers and getting excess air out of the line.

$80 for the bleed at the shop. wanna learn how. is that price typical? really glad to have it fixed.