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I got a bike with these brakes on it last season. After about 10 rides, I was having to pull the lever to the bar to get any stopping power. Took them to the shop, they bled them (three times apparently) and they were great, though my wallet was $45 lighter.

My first ride of the spring, they were still working well. But now, ten or so rides in, I'm pulling the lever to the bar again and can't even lock up my back wheel.

I asked the mechanic how to fix this and he basically said "replace them with XTR."

Are my only choices replacement or buying a bleed kit and doing them every couple weeks? I have enough messy, poisonous crap in my life already. :madman:

Thanks

Kyle
 

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The 2011 brakes have a design fault which prevents you from getting all of the air out of the system when bleeding them.

Either: Keep bleeding them as and when required.

Get Sram to replace the levers with the 2012 model - it's a known fault - hence why they changed the 2012 design.
 

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Before doing another bleed, are you certain that the brake pads are not both worn down to the backing plate? I don't have XX disc brakes, but most hydraulic brakes are supposed to self adjust for wear; however, if the pads are worn down too far, you might be exceeding the self adjusting range of the pistons.

Another possibility is that your bike shop is not bleeding the brakes properly. There are many wrenches on this forum who work in bike shops and I highly respect their opinions and inputs, but there are some not-so-competent wrenches out there as well. If the brakes are bled properly, you shouldn't have to bleed them "every couple of weeks."

Here's my take on SRAM/Avid's taper bore and improper bleed issues...

The issue of air in the reservoir is especially pronounced in the newer Avid brake levers because the "taper bore" design integrates the reservoir bladder and the master cylinder into one contiguous unit. Unlike the Juicy and previous generation Code levers, there's no separate reservoir (to compensate for heat expansion) and master cylinder connected by a port; instead, the new levers allow fluids to freely flow between the reservoir bladder and the master cylinder.

When the brake lever is pulled, the piston is advanced forward in the taper bore and eventually reaches a point where the master cylinder and reservoir bladder are separated into two separate pressure systems; it is beyond this point that the pressure generated in the master cylinder is propagated by the hydraulic fluid to the caliper's slave pistons and then to the pads.

The drawback to this design is that any air in the reservoir bladder can easily and intermittently get into the master cylinder and possibly pushed into the brake line. Once air is forward of the master piston, the pressure generated by the brake lever then goes toward compressing the air instead of actuating the caliper's slave pistons; hence the brake lever pulls all the way to the handlebar without any braking power.

When you bleed the brakes again, consider rotating the lever on the handlebar such that the bleed port is at the highest point of the hydraulic system, this combined with flicking the brake lever repeatedly should help you get all the air out of the brake lever's taper bore.
 
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