Hi, I am at the end of my knowledge so hoping for some help.
Own a 2021 Tarmac SL7 with Shimano R8070 hydro brakes. They were fine for a year or so. On a random ride my front brake went completely soft. No apparent oil leaks or anything. I bled it and was fine for a hand full of rides then went soft again. Now i have re-bled it a hand full of times and only get about 20 miles of riding before it goes dead (lever start losing pressure and eventually goes all the way to the bar)
When bleeding the first operation is to push fluid from the caliper up into the funnel. Close the bleed nipple at the caliper and operate the lever 10 times. When I operate the lever I see air bubbles coming up on each stroke of the lever. I have made sure the funnel is secure and is making a good seal. bleed nipple is tight. From here i have done a gravity bleed and the fluid coming from the caliper has no air in it... When close the bleed nipple and go back to lever operation i still get small air bubbles coming at the end of every stroke.
I am lost.
To add to the strangeness, my rear brake did the same thing about a week ago and lost pressure. It is a gradual regression of pressure but within a few miles it was gone. I followed the Shimano bleed procedure and everything was by the book. First ride was successful and it kept pressure unlike the front on the same ride.
Own a 2021 Tarmac SL7 with Shimano R8070 hydro brakes. They were fine for a year or so. On a random ride my front brake went completely soft. No apparent oil leaks or anything. I bled it and was fine for a hand full of rides then went soft again. Now i have re-bled it a hand full of times and only get about 20 miles of riding before it goes dead (lever start losing pressure and eventually goes all the way to the bar)
- i do not hang or turn my bike upside down.
- i have followed Shimanos ~20+ step bleeding process w/ proper equipment (funnel, shimano oil...)
- no obvious leaks
- i have replaced the bleed screw to make sure that seal is good. cleaned everything to ensure no debris. bad spot for sweat build up
- replaced the pads to ensure worn pads weren't causing anything
- hose connection at the caliper and master cylinder are tight, no obvious leaks
When bleeding the first operation is to push fluid from the caliper up into the funnel. Close the bleed nipple at the caliper and operate the lever 10 times. When I operate the lever I see air bubbles coming up on each stroke of the lever. I have made sure the funnel is secure and is making a good seal. bleed nipple is tight. From here i have done a gravity bleed and the fluid coming from the caliper has no air in it... When close the bleed nipple and go back to lever operation i still get small air bubbles coming at the end of every stroke.
I am lost.
To add to the strangeness, my rear brake did the same thing about a week ago and lost pressure. It is a gradual regression of pressure but within a few miles it was gone. I followed the Shimano bleed procedure and everything was by the book. First ride was successful and it kept pressure unlike the front on the same ride.
