hooligan

I've owned XTR hydros, SLX hydros and Deore Hydros.

XTRs (brake piston failure)
These XTR disc brakes had amazing performance. However, after about 4-5 years of light use, performance dropped and the brake became spongy. Spent hours of my own time bleeding before I took it to the shop, and they said the brake piston was donezo. Lever was shown to still be fine, but the brake body was done.

SLXs (nothing really wrong here, but perhaps the lever design is a bit fragile)
Stopping power on these brakes was pretty good, but not at the level of the XTR brakes. These SLX hydros have not seen a lot of wear yet, but the use of aluminum everywhere with weight saving designs seems to impact the strength of the brake. I've crashed the bike with the SLX hydros on them before. Normally I tighten my levers enough so they pivot on impact but my lever simply snapped right off. Wasn't a particularly hard crash and, obviously, levers aren't designed to withstand crashes but I was still surprised that something broke. Can't really blame the SLXs for being bad brakes here since I am uncertain about where exactly the pressure from the crash was applied to the lever.

A small thing to note: I was blowtorching my brake pads to purify them and the ice-tech cooling fins just broke off. I should've expected this, but just for future reference - don't torch your pads too much with the Ice-tech fins.

Deore brakes:
The Deore hydros have about 1 season on them. I was servicing them today, taking them off and then bolting them back on. For the front brake, I tightened the bottom bolt first - and then I started on the top bolt. I barely got a half turn after the body was clamped before the TAB of the caliper on the brake body SNAPPED OFF. I've never applied heat to this brake body or impacted it. Upon closer inspection, I realized that the brake body tapers very hard around this mounting tab and likely produced a very high stress maximum under torquing - even with a washer.

Performance:
With the exception of the XTR, the braking performance of both the deore and the SLX have been mediocre. Modulation is great, but if you're expecting 1 finger lock up cruising down the street on 160mm rotors (which my BB7s could do), you might find it difficult. Maybe it's the stock pads or something (yes, I did bed them), but braking power was not much better than the mechanicals I've had. This is with the organic stock pads. Lever feel was solid, but but the stopping power just wasn't there.

I guess I'm going with Avids / Hayes / Hopes from now on.

EDIT: Being less critical of the brakes. Obviously crashing and blowtorching aren't average use cases, but many people resort to blowtorching to cleanse pads and many people crash their bikes. The broken deore brake was definitely a surprise to me and is the primary target of scrutiny for me. The XTR piston dying was also very disappointing.

gsa103

Different thermal expansion coefficient caused the fins to break. With differing materials, heating is a traditional way to instantly break any glue bonds.

hooligan

Yep, the fins breaking isn't a really big deal to me and is definitely not a design fault. That's not really something they're built to withstand. It didn't even have to do with a different thermal expansion rate - just overheating the aluminum.

osco53

Never had a single problem with My Shimano wet brakes,,,

NoPhart

You will if you take a torch to them!

Who in their right mind would take a torch to any aluminum product with rubber/plastic/teflon internals?

Canker

I'm sure he took the pads out before he did it. Torching your pads is a fairly well known way to clean oil off them.

hooligan

1) Yes, of course, I took the pads out of the caliper.
2) I should've supported the pad so that it wasn't laying on the fins while I torched them. I did not expect the aluminum to heat enough to deform while trying to get the pads to smoke.
3) Most of the use cases that resulted in breaking were due to some sort of misuse (over-torquing, torching) but not by a massive margin, which leads me to believe the safety factor of brakes is low. Why? To save weight. People care about weight, and this is where shimano will do their best to outdo their competitors. I'm not a big fan of shaving 10-15g/caliper to lose significant strength. I've swapped brakes DOZENS of times before with no problems. This is the first time I've had an issue.
4) There were use cases which showed poor engineering - i.e. no breakaway clamps on the shimano levers isn't good. AVerage/mediocre 1 finger braking performance on 160mm rotors (locking up was fairly difficult but doable. At least lever feel was good).

They're definitely a decent brake for the price, but...if I had to do it again, I'd probably avoid the Deore/SLX line at least.

DMC707

OK --- so?

Bikernator

I feel your pain, man. It sucks when something fails in a manner you perceive as below the threshold of tolerance.

I guess the takeaway here is that the torque values are actually very important nowadays - as inconvenient as that may be for those of us who prefer to fly by the seat of our pants.

The general consensus seems to be 'get over it, get a torque wrench.' I don't have enough experience to give you a better recommendation on brakesets. Sorry.

I had the same thing happen to me on a Stihl chainsaw. The bar studs threaded into a thick polymer part of the power head. When I stripped it out I was furious (why the HELL would you put threads into plastic on something that has cyclic loading and in-field tightening?!?)

Eventually I calmed down and realized I needed to chill out with the wrench. Several years later when it was time to buy another saw - straight to Stihl. They make a great product, I just needed to pay more attention. May be the same thing for you...

Darth_Firebolt

There are much easier, less destructive, smarter ways to clean contaminated brake pads.

Do not use a product outside of the intended design parameters and then whine when it breaks. This is basic common sense stuff.

Phantoj

worthless without pics...

I'm not seeing how torquing up your brake caliper should put any bending stress on its mounting tabs. Maybe something what misaligned?

Cyclist0108

I have Ultegra hydraulic brakes, which are basically the same thing as XT, south of the brake levers. The rear caliper failed (leaked all over everything) within the first 4 months of ownership (Shimano warrantied the part, but not the contaminated pads or disc). I find that I have to keep the pistons scrupulously clean, or else I have the constant annoyance of some rubbing/slow retraction after braking long and hard. I also find myself having to reset the pistons fairly frequently. What concerns me the most is that I wear through both pads and rotors on a very regular basis (like every few months). By contrast, I have only replaced pads twice on my mountain bike in 10 years (Juicy 3 or something), and I might still be on the original rotors. The road bike gets a lot more use, but still.

On the positive side, they are very easy to bleed and maintain, and mineral oil is safe to drink, whereas automobile hydraulic brake fluid is not something I (as a chemist) would ever want to touch. I've been very impressed with their stopping power and modulation properties. But they do seem to be very high maintenance (admittedly, I have never blow-torched my pads). There is clearly a lot of room for improvement. A "normal" cyclist would find these too much trouble to maintain and adjust.

corrado33

Was going to be my comment. OP whines when blow torching pads... Hilarious. Whines when calipers don't have stopping power after being told that the calipers need replacing. (And after 4 years of use!)

Would you like some cheese with that whine OP?

You must have really weak fingers because I can lock up either of my wheels with one finger on my crappy, bottom of the barrel, tektro hydraulic brakes. Hell, I can lock up most wheels with RIM brakes and one finger. I vote incorrect setup.

gsa103

A lot of it depends on tires, riding position, and bike geometry. I can lock the front tire on my road bike with Ultegra calipers no problem. Same on my Giant Toughroad, with budget Shimano hydraulics (160mm).

My Yeti 575 (older XTR) has 26x2.35 tires, slack geo, and a long wheel base. Even with 180mm rotors, I can't really lock the front wheel. Stopping distances are significantly shorter than my other two bikes though, the difference is more tire traction and significantly harder to endo.

My previous mountain bike had Tektro hydraulics, and I can believe they have more power than Shimano. It seems like Shimano trades some power to achieve better feel. I definitely felt that I needed to upgrade to 180mm rotors to get the braking power I wanted.

Doohickie

Meanwhile, my 33-year-old caliper brakes still work great.

Spoonrobot 

lol what mountain bike is running caliper brakes?

Cyclist0108

A 33 year old one. (I had one from about 1992 that had cantilever brakes). I think some of our kids' mountain bikes have V-brakes, which are sort of satan's spawn of those and calipers.

hooligan

Whoa, let's turn down the hostility. Do you work for Shimano?

Most items on bikes are not guaranteed to withstand abuse - and I acknowledge it. No shifter/lever on your bike has any guarantee that it will survive a hit with a tree branch. Almost no phones have guarantees that they'll survive a drop. There is the intended use case, and there are always going to be scenarios where you push the envelope of your equipment. It's nice when your brake levers don't crack when you have a crash, and it's nice when your phone withstands a drop without breaking. Unfortunately, these are the first brakes that have failed on me. I'm not 100% sure if I overtorqued them, but my previous Avids and my friends' Hopes never had any problems. I'm providing a data point for you:

- Safety factor for mechanical strength on these brakes appears to be low. Slight overtorquing and mild impacts cause brakes to be irreparably damaged where other brakes have not suffered the same problems.

To clean the pads, I've used car brake cleaner, carb cleaner and sandpaper. I know how to bed pads. I did not resort to blowtorching on a whim.

You misunderstood the situation with the XTR brakes. I did not use them frequently over those 4 years and when their performance dropped enough, I bled them to no avail. I went to a shop and was told they were toast. I have 3 other bikes with disc brakes - all of which were ridden more and did not have any brake failure.

Regarding setup, you might be right. I spent quite a bit of time on the deore's and SLXs. My standards were similar to my XTR brakes when they performed like new - if I 1 finger brake hard enough, I should be able to damn near launch myself over the bars, even riding on the street, while sitting. The Deores and SLXs appeared to be weaker than the XTRs despite a very solid feeling factory bleed, new rotors, new pads, bedded in. The blowtorching was the next step for fear of some contamination that occurred. Maybe I was missing something else.

tl;dr - sit down, stop being a hostile prick, let your steam off somewhere else

hooligan

For my scenario, I would've either chosen to replace the pads or blowtorch them. I already applied solvents and sanded the rotors. No additional performance was gained from doing so, so I chose to blowtorch as a last ditch effort. I'm not really whining about the fins falling off - I honestly don't care and I know they broke because of my blowtorching. I just decided to note it.

Spoonrobot 

It was sarcasm. He's in the wrong thread for that noise.