How do I bleed Avid Elixir brakes
All Avid brakes require the proprietary brake bleed equipment and that a fairly complex procedure is followed. Avid/SRAM sell a brake bleed kit that comprises:


two syringes
caliper and level hose barbs with hose and clamps
T10 Torx allen key
DOT 5.1 brake fluid
caliper spreaders to hold the caliper apart while bleeding


The kit is quite expensive and several eBay sellers provide a cheaper alternative kits. Any hydraulic brake fluid that complies with the DOT 5.1 standard is suitable for Avid brakes. It is possible to assemble your own brake bleed kit by sourcing some 20ml syringes, M? hose barbs, neoprene hose, hose clamps and using some US quarters or UK 2pence pieces to spread the calliper pistons.

The bleed procedure is documented by SRAM in a youtube video: 


                
            

and also in their service manual PDF:

https://www.sram.com/service/techdocs/hydraulic-disc-brake-hose-length-adjustment-bleed-guide

The procedure involves:


prepare the brake fluid by using a partial vacuum to remove bubbles from the fluid
connect a 50% full syringe to the caliper and 25% full syringe to the lever
close the brake lever and clamp with a rubber band
pull on the caliper syringe gently to remove bubbles from the caliper
push the caliper syringe until around 25% of the fluid has transferred to the lever syringe
open the lever while gently applying pressure to the caliper
remove the caliper syringe and replace the bleed screw
pull gently on the level syringe to remove bubbles from the caliper
apply the brake lever and repeat until all bubbles are removed
remove the lever syringe and replace the bleed screw
clean all traces of brake fluid with alcohol or soapy water


At this point you should have properly bled brakes. Test carefully before heading back out on the trail!