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Discussion Starter · #1 ·
I recently upgraded my Avid Juicy Three brake to a Shimano XT up front, and I loved it so much that I started looking for a new rear brake as well.

I scored a new SLX rear brake, with pads and proper length hose for $65. From what I've been reading the SLX and XT brakes are almost identical, so I thought it would be great. However, after about 2 weeks of use it's obvious that there's either some large differences in the two brakes, or there is something wrong with my SLX brake.

First of all, the lever from the XT brake is much smoother than the SLX brake, but that's not a big deal at all. I don't even notice it when I'm riding.

The thing that bothers me though is that the SLX brake is very inconsistent. after a bumpy uphill I will go to brake, and the lever will come all the way back to the grip, and I will need to use two fingers so I can get the full range of motion from it (or else my middle finger blocks the lever from coming all the way back).

And on the downhills the SLX brake will start off weak, and I will have to pump the lever once or twice before it will work well. Luckily the SLX is on the rear so I can continue braking with the XT while I pump the SLX.

Are these problems I'm experiencing just because the SLX is a "lesser" brake than the XT, or is there something wrong with my SLX that is causing it to act this way?

Here's the XT brake lever when I am applying enough pressure to completely stop the tire in a riding situation.


And here is the SLX lever being compressed with one finger.


And here's how I have to hold the SLX lever to get as much stopping power as my XT.
 

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Thats not to much$$. How do you store your bike? I used to store my bike upside down on the ceiling until I realized whatver air was in the reservoir would make its way into the system. My brakes were always spongy at the trail head.

cent frum my fone so don't cumplane about spelling or grammer
 

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Discussion Starter · #5 ·
Thats not to much$$. How do you store your bike? I used to store my bike upside down on the ceiling until I realized whatver air was in the reservoir would make its way into the system. My brakes were always spongy at the trail head.
I store mine right-side-up, but maybe there is just a decent amount of air in the system, regardless. Do you need special syringes, or will something like this work fine?
Large Plastic 100ml Syringe + 47in handy plastic tubing: Amazon.com: Industrial & Scientific
 

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Your problem is air. Your SLX brake reservoir simply has excessive air. Simple fix - Bleed and top off reservoir. When excess air is available in the brake reservoir and you're the teeth-jarring bumps, the brake fluid in the reservoir becomes turbulent and air socializes with the brake fluid. Now we squeeze the brakes and we have introduced that air/fluid mix through the master cylinder and into the system. Yep, that lever now comes perilously close to the grip at the least opportune moment. Not a confidence inspiring .

The same reason why some can't or won't store their bike vertical because air in the master brake reservoir. Because of the angle, the air in the reservoir simply finds its way into the master cylinder and this results in people complaining. The simple fix to this problem is KEEP THE RESERVOIR TOPPED OFF. No air, no problem. Now we're not referring to system leak or something like guys...that's another discussion.

Bleeding is the obvious second step here. Not worth going into here, but look around...bunches of threads and videos on bleeding these SLX's, XTR's or XL's. It's remarkably easy, just take your time and have everything at hand before you begin. Exercise patience and you'll be riding faster than you might think. Good Luck!
 

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Chances are you won't even need to bleed the brake, all you need to do is pump the lever a few times till it feels solid then top up the reservoir. I had the same issue when I botched the hose cutting & shortening on my SLX brakes. I was too lazy to bleed them so I just pumped the lever a few times, added oil to the reservoir, and repeated a few times until no more bubbles came out of the fill port. All I did was get my local shop to fill up a small squeeze bottle with mineral oil, then used that to top up the reservoir through the fill port on top.

If that doesn't work, then do a bleed, but chances are you won't need the bleed, Shimano's brakes are almost self-bleeding unless the air bubbles are way down in or near the caliper.
 

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Discussion Starter · #8 ·
Chances are you won't even need to bleed the brake, all you need to do is pump the lever a few times till it feels solid then top up the reservoir. I had the same issue when I botched the hose cutting & shortening on my SLX brakes. I was too lazy to bleed them so I just pumped the lever a few times, added oil to the reservoir, and repeated a few times until no more bubbles came out of the fill port. All I did was get my local shop to fill up a small squeeze bottle with mineral oil, then used that to top up the reservoir through the fill port on top.

If that doesn't work, then do a bleed, but chances are you won't need the bleed, Shimano's brakes are almost self-bleeding unless the air bubbles are way down in or near the caliper.
That's super simple, thanks for the advice. I'll try it out. It should work since my brake works after pumping the lever a few times.
 

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Discussion Starter · #10 ·
Chances are you won't even need to bleed the brake, all you need to do is pump the lever a few times till it feels solid then top up the reservoir.
I finally got around to doing this, and it definitely made the brake more consistent... Still a bit sloppier than my XT though, so maybe I need to completely bleed the SLX, or maybe the XT lever is just better than the SLX lever.

A bad day of cycling is better than a good day at work
If that's true then I think you need to find work you enjoy more ;).
 
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