WHY Avid brakes are unreliable.

PB Forum :: SRAM
WHY Avid brakes are unreliable.
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Posted: Nov 29, 2013 at 9:05 Quote
The editor of Decline Magazine recently created a stir by recommending that anyone who has Avid Brakes should "replace them a.s.a.p."

http://www.ridemonkey.com/forums/f19/offseason-drama-drama-drama-263148/

While some people were offended, others agreed Avid brakes have issues with reliability. What I didn't like was that he didn't provide any reasoning behind his recommendation. That is what I want to explore, figuring out why so many people have problems with them. I have a theory based upon evidence I have seen in my experiences working and riding with Avid brakes.

The main problem with Avid brakes is that there isn't enough oil in the system to operate for long durations without being bled, especially when doing rides that involve repeated long descents. The main point of evidence comes when changing brake pads that are almost completely worn. It is not uncommon to not be able to push the pistons in Avid brakes all the way back so that you can install new pads. Why won't the pistons go back in all the way? Likely either because air has leaked into the system. The other possibility is that the brakes were bled (likely because of air leaks) after the pads were partially worn so now new pads won't fit in. I haven't experienced this problem with other brakes, and I think it is due to a lack of an adequate oil expansion chamber in Avid brakes. The limited amount oil starts to boil on long descents, and air is forced into the system. Bleeding the brakes wil fix the problem, but then when you go to change your worn out brake pads there is actually too much oil in the system and you have to bleed them again. I never have these issues with Shimano brakes, which have the larger oil expansion resovoir on top of the brake lever. The Avids have an expansion bladder inside the lever, but it looks pretty limited. Another problem could be that the brakes don't have enough oil flow inside the cables, but the inside diameter of Avid brake cables is similar to other brands. I think what the problem might be is essentially a defective design born out of the pursuit of achieving the lightest weight possible. Maybe the SRAM engineers think because they are using DOT fluid instead of mineral oil they can get away with having less oil in the system? They claimed to have supposedly improved their seals in 2012, but I don't think that's what the problem is.

Any feedback, criticism, or other ideas are appreciated, I just want to get to the bottom of why Avid brakes are unreliable.

Posted: Dec 11, 2013 at 0:11 Quote
I was riding my new XO trail brakes the other day and they momentarily faded on a long freezing descent. Only happened once, during one pull of the rear lever but it was disconcerting because I was hoping there would be no issues with the new XO trail 4 piston brakes. The pads are about a third of the way worn down, so if I bleed them again now they will hopefully be good til they need new pads but then I will likely bleed them again also because there will be too much oil to get the pistons all the way back for new pads to fit. Could you imagine if brakes on cars were this finicky? It would be completely unacceptable.

Though I consider the brakes somewhat unreliable, I did like the feel of them and they feel similar to the Codes in terms of power. Speaking of my Codes, I left my DH Bike in the often freezing garage and both of the Code brakes on it went bad, could pull the levers to the grips. Again, can you imagine if your car brakes did this...unacceptable. More bleeding to do...really wish they used mineral oil instead of the toxic dot oil.

I'm not a Sram hater, I actually am a big fan of Rock Shox forks even though I think the Boxxer is behind the times now with the new DVO, Marzocchi, X-Fusion, etc.. forks on the market. I just wish Sram would test there products a little more rigorously and thoroughly like Shimano does. Sram has recently had to recall it's Wifi road rear derailleur and it's Red disc brakes for road because there apparently wasn't enough testing done. The rear derailleur seizes up, which is coincidentally an issue some of their past mountain bike derailleurs had even though there were no recalls. They always warrantied them in my experience. Never seen it happen with a Shimano derailleur. I can't believe after all the thousands of disk brakes that they have warrantied that they haven't taken a more serious approach to making sure their products are reliable, given what it can do to a companies reputation.

Oh well, I'm still looking forward to a discussion on here about their brakes, and am open to other theories and ideas, including the one that I could be wrong about mine.

Posted: Mar 29, 2014 at 8:03 Quote
Looks like the editor of Decline was justified, and my theory was completely correct for the most part. SRAM has confirmed it with the release of their new Guide brakes which have a new design (actually similar to the old Juicy design) that has increased oil volume.

http://m.pinkbike.com/news/first-look-sram-guide-rsc-trail-brakes-22014.html

The article promoting the new brakes, written by Richard Cunningham, starts out with:

"SRAM has developed an all-new braking system that handily addresses the minor deficiencies of its Avid XO and XX1-level trail brakes."

Yeah, minor deficiencies that have resulted in thousands of failures out on the trail that prematurely ended rides and put riders and racers at risk, and that produced thousands of warranty claims that were a hassle and profit killer for bike shops around the world. Not to mention the thousands upon thousands of dollars and hours spent, or sometimes wasted, on bleeding their brakes so frequently because of what was essentially a defective engineering design. Not to mention all the cancerous, toxic dot fluid that was unnecessarily spilled all over the place and on hands in shops and garages across the world because of a design that didn't have enough fluid in the system and therefore required more frequent bleeding.

The key sentence in RC's apologist review is this one:

"More fluid volume was added to the reservoir to ensure that there would be ample reserves to compensate for 100-percent pad wear..."

That was the reason SRAM's Taperbore brakes had a problematic, if not defective design, and the reason why I complained about their brakes in the first place. The Taperbore design of their brakes apparently doesn't allow for enough oil to compensate for 100% pad wear, and also creates other reliability issues that are made worse by their use of DOT fluid, which can deteriorate seals over time.

I fully expect SRAM to do away with all their Taperbore design brakes, so expect to see replacements for Code brakes released next with a new design similar to the Guide brakes, further confirming that it was a defective, problematic design.

The right thing for SRAM to do would be to recall all of their Taperbore design brakes, or at least the most problematic ones, such as pretty much every Elixer brake ever made.


☆If you have Elixer brakes I would encourage you to insist upon getting them warrantied as soon as possible, whether you have had problems or not. The justification is obvious, and I've read about them replacing Elixers at events such as Crankworx no questions asked, and without proof of purchase, so you should feel no shame in requesting that they simply provide you with reliable, safe brakes that don't suffer from a defective design.


Did I already mention that SRAM had a recall on their road bike disc brakes that also had a defective design due to poor engineering and lack of testing?

http://road.cc/content/news/101693-sram-issues-stop-use-immediately-warning-red-22-and-s700-hydraulic-brakes

Another part of SRAMs solution to this public relations debacle is to kill the AVID name and simply call their brakes SRAM, one of the strangest, most boring brand names ever invented that coincidentally rhymes with Spam. Does anyone else see the humor in this? SRAM bought the once-respected AVID name to bolster their reputation in making brakes, then destroyed the name by making the worst brakes ever, and now are discarding it to the trashcan along with the old model names. It's like a corporation getting a new haircut, and pretending that they never had a God-awful mullet that for years they thought was awesome.

The whole debacle makes me wonder if there should be more government involvement in the design of bicycle braking systems the way there is with bicycle helmets. This would ensure that companies like SRAM would not put their marketing priorities ahead of the public's safety, making mountain bike riders and racers gunea pig safety testers because of a lack of adequate engineering and testing of products that they consistently rush to the market.

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