Air in hydraulic brakes after bleed Today I bled an Avid Elixir 1 after it had gone soft over the winter. I followed the directions in the Park Tools Big Blue Book completely, used an Avid bleed kit and opened a new bottle of DOT 5.1. The bleed went well and the lever had good pressure afterwards.

I went out for a couple of hours and came home and thought the brakes seemed softer. I stood the bike on its rear tyre and pumped the brake 10 times and by the end the lever was against the grip.

I checked both plugs and they seemed to have a good seal.

Any ideas on what I could have done wrong or could be wrong with the brakes to allow significant air into the system?
Your bleed was probably not perfect. It is normal. Pulling a perfect bleed is a bit hard for first timers.

Possible reasons for a not perfect bleed:


you did not fully reset the pistons before starting the procedure
you did not apply enough negative pressure and move oil from one syringe to another many times in order to remove all the air bubbles
you did not bleed the lever (push the lever all the way in and apply negative pressure on the syringe on the lever)
you introduced some air (and/or lost oil) between the time you removed the syringe and fitted the torx screw back in
you introduced air from the sirynge accidentaly (a bit rare)


My suggestion is to rebleed (not fully, but just enough to remove the air). Push oil from the bottom (caliper) using a 90% full syringe and pull from a 10% full syringe from above at the lever. While doing so, stop pushing from the bottom and continue pulling from above to apply negative pressure. You'll probably see 10-15 bubbles appearing at the top syringe.