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I have bled Avid Elixirs 3, 5, CR, etc... I still have a hard time getting a "good bleed." I follow the instructions online, and via Avid's youtube video, I use the kit and it still takes me going through the entire bleed process 3 or 4 times until I give up and decide it's at least better than it was.

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closed as primarily opinion-based by Batman, freiheit Mar 23 at 2:45

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise.If this question can be reworded to fit the rules in the help center, please edit the question.

    
Certainly, some degree goes to design of the bleed kit and the brake system, but some of it is the person who does the bleeding (I have no doubt that there are professional mechanics who can bleed Avid systems quite well, easily). A better question to ask might be "How do I bleed Avid brakes?" and describe what goes wrong for you when you follow Avid's instructions, or something similar. –  Batman Mar 21 at 22:17
    
Thanks Batman, I know how to bleed the brakes (At least follow the steps), the issue I usually have when I'm done, and put the screw back in and pull the lever for the first time it goes right down to the bar, with little or no resistance. –  TravisK Mar 21 at 22:29
    
Do you understand the concept? Following instructions will only get you so far, if you don't understand the purpose of what you're doing. –  Daniel R Hicks Mar 22 at 2:52
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Maybe they are just bad brakes. That's what I hear in my local trails. Also have a look at bluetoad.com/publication/… ("we completed the avid bleed process and we where pleased with the performance for short period of time before they began to act up again.") –  cherouvim Mar 22 at 14:20

1 Answer 1

up vote 5 down vote accepted

It's the design that makes them harder to bleed. Although an 'open' hydraulic system Avid's Taperbore resembles a 'closed' system, one that operates in a vacuum. The Avid system uses a small reservoir fixed amount of fluid in the system and a bladder around the master piston with air in it. Shimano and other brands use a larger reservoir with a bladder separating the brake fluid (in the case of Shimano mineral oil) and air. In both cases air is used to compensate for the fluid in the system expanding.

Because the Avid system operates in a vacuum it requires all air to be removed from the system and that is why you need the two syringe set, other designs simply require fluid to be topped up in the reservoir and air worked out. The Avid elixir system is further complicated by a design that traps air within the taper bore reservoir adding an additional level of difficulty when purging air.

Avids also use DOT 4 or 5.1 which is more difficult to work with than other fluids. Different brake fluids have different characteristics (boiling points, freezing points, amount of expansion etc.). Avid specifies DOT 4 and 5.1, which is a pain. The brake fluid is a solvent so you don't want to get it on your hands but it isn't going to kill you. DOT fluid is hygroscopic, it attracts water so although you can buy it in larger quantities cheaper than through Avid it doesn't have a good shelf life once opened and probably shouldn't be opened again.

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Good information DWGKNA. I Didn't understand all that before about the open and closes system. This gives me a couple ideas to try to bleed more successfully. One other interesting thing I notice with my current brakes is that when I am wheeling my bike around on just the back wheel with the front wheel up in the air, my break looses all pull and goes straight to the grip with no resistance. Once returning both wheels to the ground, the brake returns to normal. Any Idea why this would happen? –  TravisK Mar 23 at 5:12
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That's a common test for Elixir brakes and is used to indicate if there is air in the system. All the air in the system rises to the top and surrounds the master piston. Ideally you should be able to pump the brake 10 times with the wheel up without the lever touching the bar. –  DWGKNZ Mar 23 at 17:15

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