Ruined $150 Shimano Deore hydraulic brakes

MarkJohnston

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Hello,

I just ruined a $150 shimano deore hydraulic disc brake just by the fact that ebikes are heavy and going fast 25 mph - 36 mph. I think they just get too hot and melt the piston seals. Anybody have any thing to chime in? Any hydraulic disc brake set ups they recommend?

Im using good technique and everything but I ride my ebike more than anybody else. I do about 50 miles a day. I just burned through a set of pads like matches. I am not a fair weather cyclist and I like to ride as fast as can, nearly all the time.

so i need brakes that aren't going to get too hot. im still not really sure why the brakes failed. I can't bleed them, they're clogged somewhere and they don't currently provide any braking power.

My bike weighs 100 lbs. MY batteries and cargo mounted to the rear rack weigh 50 lbs. I weigh 160 lbs. All total it's somewhere around 310 pounds moving fast all the time. It might just be over kill on my front hydraulic. I don't use the rear brake because I skid out. no traction there.
 
MarkJohnston said:
Hello,

I just ruined a $150 shimano deore hydraulic disc brake just by the fact that ebikes are heavy and going fast 25 mph - 36 mph. I think they just get too hot and melt the piston seals. Anybody have any thing to chime in?
Oh I am sure Chalo will chime in :lol:


Any hydraulic disc brake set ups they recommend?
electric brakes, low or high, eabs.

Im using good technique and everything but I ride my ebike more than anybody else.
I do about 50 miles a day. I just burned through a set of pads like matches. I am not a fair weather cyclist and I like to ride as fast as can, nearly all the time.
Just buy a motorcycle or moped, scooter.

so i need brakes that aren't going to get too hot.
So the pads were rubbing?

im still not really sure why the brakes failed. I can't bleed them, they're clogged somewhere and they don't currently provide any braking power.
Try mechanical disk brakes

My bike weighs 100 lbs.MY batteries and cargo mounted to the rear rack weigh 50 lbs. I weigh 160 lbs. All total it's somewhere around 310 pounds moving fast all the time. It might just be over kill on my front hydraulic. I don't use the rear brake because I skid out. no traction there.
 
I have an idea. Keep rear brake very strong. Hard pull on front then hard pull on rear. Skid. Hard pull on front.

Just alternating back and forth. Like an ABS. HARD FRONT pulls for emergencies. A super hard pull will snap spokes on my 32h front. Sort of modulated. Doing this semi modulated hard pulls on both front and back might help significantly reduce the heat build up.

It's going to have to work. I just looked at electric motorcycle prices. :shock:
 
Alternating keeps it cool. My disc brakes HOWL and get load really quickly. They get stupid hot even going down hill
 
Why not roll around with a bottle of water to cool the brakes, just have a rubber hose taped to the bicycle tube so it can drip water, after you brake turn the lever of water.
 
Try cleaning them out with some spray cleaner and a brush. Could be clogged with brake dust.

Might want to look at 220mm diameter rotors with extra thick rotors and 2 pot calipers.
 
markz said:
Why not roll around with a bottle of water to cool the brakes, just have a rubber hose taped to the bicycle tube so it can drip water, after you brake turn the lever of water.

I heard that could warp them.
 
electric_nz said:
Try cleaning them out with some spray cleaner and a brush. Could be clogged with brake dust.

Might want to look at 220mm diameter rotors with extra thick rotors and 2 pot calipers.

I have a 4 pot caliper. I have 180mm. My max size of rotor is that unfortunately. Would have to upgrade shock to a down hill fork. Expensive. There is the ice tech freeza rotors. I have the ice tech normal. Ice tech Freeza ONLY CENTERLOCK. CENTERLOCK. boo. The freezas really shed heat like crazy. i would have to upgrade a whole different wheel. very expensive, but possibly...
 
markz said:
Why not roll around with a bottle of water to cool the brakes, just have a rubber hose taped to the bicycle tube so it can drip water, after you brake turn the lever of water.

do you mean the caliper or the rotors?
 
electric_nz said:
Try cleaning them out with some spray cleaner and a brush. Could be clogged with brake dust.

Just did this and can confirm it did NOT work. But I was able to verify that the fault is somewhere in the caliper. Either a manufacturer defect or my own fault.
 
Yes the pads were rubbing a bit, does that contribute to heat build up? My rotor is ever so slightly out of true. A car pulled out in front of me and I bent my front wheel in half to stop in time.
 
If the pads were rubbing, that will definitely build up some heat ahead of a hard stop...

If the seals are deformed/melted, the current calipers are toast.

One option is to switch to a direct drive hubmotor with a regen controller. You also might consider a mechanical disc brake on the rear, so at least one brake will not have the rubber seal issue.

I wish I had better answers. Best of luck...
 
Shame larger rotors are not an option, is it because the fork is not rated for them? What pads are you using? Pads made from different materials (metalic/ceramic) will last longer, not overheat, and insulate the heat from the pistons. Pads with heatsinks will also shed heat better. Of course first make sure they aren't rubbing and the rotor is true. Also with all that weight on the rear how do you not have enough traction to use the rear for braking, maybe a better rear tire or mount the weight lower so you have less weight transfer to the front under braking.
 
OP, did I miss what kind of riding you're doing?...off road, street-only, or something else? If your bike weighs 100 pounds, I'm thinking this is not an off road MTB application...right? My Santa Cruz Nomad with a dual crown coil fork and coil piggyback DH shock weighs 50 pounds without battery. Is yours a fat tire model?

Regardless, like you I discovered my Nomad when converted from pedal-only to BBSHD mid-drive was overwhelming my good quality single piston brakes...or at least requiring much more lever pressure that was taxing my hand/wrist strength during a long off road ride. 4-piston brakes are almost a necessity on powerful ebike applications that are ridden aggressively, and I can see that for off road and/or pavement. Bikes with powerful motors and this much weight will tax single piston brakes. I also run a 200mm front rotor and 180mm rear. With 4-piston brakes this rotor size has been quite adequate and with less wrist, hand, and arm pump. I notice just about all the big emtbs from Trek and Specialized come with 4-piston brakes, so that says a lot there.

Cable pull brakes...I've used them in years past, and I rate them as above any cable pull rim brakes...especially the Avid BB7's...but they just don't have the power and lever pull ease of good hydros...they just don't, especially for heavy bikes and/or DH level braking requirements. Not everyone or every application absolutely requires hydros or 4-piston hydros, but a good set of hydros makes life a lot easier. It's hard to find many good sets of 4-piston hydros in this market at the moment. I was able to find a set of Tektro Orion M745 4-piston brakes, and they have been awesome. They are basically designed like a set of Shimano XT 4-piston brakes...even use the same brake pads...and I'm even suspicious that the Taiwan based company makes some of the components for Shimano.
 
It should be pretty difficult to impossible to actually melt down a set of hydro calipers. You can definitely over heat them and take them out of their performance window, however heat up to the point of melting piston seals, that is unlikely, unless you have poor braking technique.

There are a few things to be aware of:
-Use metallic pads and rotors that support them. Shimano is one of the few mfg's that makes resin pad compound specific rotors. I am not a fan of resin/organic pads in general either on my push bikes or my ebikes.
-Use appropriate rotor sizes. There isn't a limit to rotor sizes on forks. You can have a crappy fork that is dangerous to begin with, which is likely because most ebikes come with some pretty shit forks, and a lot of teh forks I see used on this forum, I wouldn't touch with a 10' pole. however with the right adapter, any post or IS mount fork can support a 200mm rotor. I highly suggest 200mm minimum... I won't even ride my 25lb xc marathon bike without 200mm rotors.
-Check that your brakes are setup properly. No rotor rub (not only when cold, but also when hot) if you don't have a complete/proper bleed on shimano brakes, the pistons will extend and retract with heat and the pad to rotor clearances will change. Bleed the system using the funnel and moderately good mineral oil, before you pull the funnel, tip the lever down (don't let air reach the bleed hole) and flick the lever, you should see more bubbles come out.
-Brake in stabs. high pressure, short durations. You might think you already do this... but braking systems on bikes are like braking systems on cars, they do not want to roll to a stop, they want to go from rolling speed to stopped quickly and then be let off. Don't sit with your brakes on at a stop light, or after they've gotten up to temps. Letting the pads touch the hot rotors is the one thing that imparts heat back into the caliper and fluid. The rest of the fade and heat generation you feel is located within the pad, rotor interface and won't go back up the system.
 
Go to your local moto dealer and look at the brake system on a 125cc bike and that is basically the minimum of what you need. You will see thicker rotors, larger calipers, larger lines and resevoirs at the brake levers. Bicycle components are under sized for your speed and load requirements no matter how you apply them.
 
Now is a good time to remember that a rim brake has a much bigger, heavier rotor made of much more thermally conductive material and exposed to a much greater amount of ambient air. A rim brake can discharge more heat for longer before it is damaged.

Cables don't leak out if they get hot (which they don't, at least not from braking). Rim brake pads don't lose effectiveness if a cable accidentally touches them. Rims don't warp from braking heat.

If you don't have a good way to install rim brakes, then you can use a thicker, larger diameter disc rotor and a good cable actuated caliper like Avid BB7. Both these things will raise the threshold at which heat buildup from braking becomes a functional problem.

My e-bikes are in the 450-500 pound range with me on them. Although some of my bikes have disc brakes, my e-bikes both have rim brakes that work great. One of them has a rear drum brake that also works just fine. I trust all these brakes to withstand adverse conditions and hard use better than any disc brake.

The pedicabs I help to manufacture and service run at gross weights exceeding 2000 pounds sometimes, and they all have electric assist now. They use Avid BB7 brakes with 203mm rotors. They go through pads pretty quickly, but are otherwise satisfactory.

I don't think your braking requirements are unreasonable. I think assuming hydraulic discs are the best solution for you might be.
 
Can't say I agree at all with mechanical disk brakes. they are pretty crappy and every one of them except for pauls or trp spyre have a moving caliper piston only on one side and the other is fixed. It's an inferior design to be perfectly honest. BB7's were some of the better ones at the time (this was pre trp spyre) but they are still shite in the context of modern brakes and have no place on machines where back country serviceability isn't the #1 build logic and priority.

Part of your problem is your technique. You say you're only using front brake because the back skids... This is from improper technique in general. you need to shift your weight back, balance the weight transfer as much as possible and use both brakes. If you have a totally crap fork that is under sprung or using elastomers, this is exacerbating the problem because you have needless weight shift to the front of the bike so I would suggest locking out the front fork. You should absolutely be able to do 35-40% of your braking work with your back brake. In times of absolute threshold, that number will drop to 20%, but only for brief milliseconds in the braking process.

300lbs of weight is a lot of weight, but it's not really much more then many dh and full enduro mtb riders. I ride with a guy that is 265lbs, 6'7" and he absolutely shreds on his 38lb enduro bike. He runs 220mm rotors and sram code rsc brakes, and he like me, rides downhill grades in excess of 20% often. his brakes get hot enough to smell hot, and make ticking noises when they are cooling off, but no fade and no damage to the system.

What shimano brakes do you have? Shimano brakes have a whole host of issues depending on generation. Many generations leading up to the m7xxx, m8xxx and m9xxx have issues with weaping lever seals, and also cracked and damaged ceramic and/or phenolic pistons. This would apply to M6xx, M7xx and m9xx. This is common and isn't necessarily due to heat, but rather due to just getting brittle with age. You can rebuild the calipers with new pistons and new seals, and right now with parts availability, that may be the better option.
 
ebbsocalMTB said:
BB7's were some of the better ones at the time (this was pre trp spyre) but they are still shite in the context of modern brakes and have no place on machines where back country serviceability isn't the #1 build logic and priority.

I've never seen a BB7 with sticky pistons, leaks, or an air bubble in the cable. They just work until the pads wear down, even with a 2000 pound pedicab. A majority of the hydro brakes that come across my stand, even if the bikes were brought in for unrelated service, have problems. Main Street Pedicabs use hydraulic rear brakes, and almost every single one of them I ever come across needs a couple or three squeezes of the rear brake lever to pump up before the brake starts to work.

Spyke and Spyre are pretty good, but they go out of adjustment much more often than BB7, and the adjusters get stuck sometimes. One of my coworkers switched back to BB7 on his polo bike to reduce maintenance.

Bicycle rotors are designed to flex to meet a fixed pad, so opposed piston actuation is nothing more than a vanity feature to appeal to a childish desire for symmetry (like dual front discs, or centerpull calipers back in their day). None of my motorcycles (back when I rode those) had opposed piston brakes-- and they were all heavy, high performance machines.
 
Chalo said:
ebbsocalMTB said:
BB7's were some of the better ones at the time (this was pre trp spyre) but they are still shite in the context of modern brakes and have no place on machines where back country serviceability isn't the #1 build logic and priority.

I've never seen a BB7 with sticky pistons, leaks, or an air bubble in the cable. They just work until the pads wear down, even with a 2000 pound pedicab. A majority of the hydro brakes that come across my stand, even if the bikes were brought in for unrelated service, have problems. Main Street Pedicabs use hydraulic rear brakes, and almost every single one of them I ever come across needs a couple or three squeezes of the rear brake lever to pump up before the brake starts to work.

Spyke and Spyre are pretty good, but they go out of adjustment much more often than BB7, and the adjusters get stuck sometimes. One of my coworkers switched back to BB7 on his polo bike to reduce maintenance.

Bicycle rotors are designed to flex to meet a fixed pad, so opposed piston actuation is nothing more than a vanity feature to appeal to a childish desire for symmetry (like dual discs, or centerpull calipers back in their day). None of my motorcycles (back when I rode those) had opposed piston brakes-- and they were all heavy, high performance machines.

As a former bike shop employee... I've seen everything when it comes to brakes. I've seen just as many poorly adjusted bb7 brakes as I have hydro's that are improperly blead. The truth is, few people maintain their machines like they should, no one wants to hear a 50/100 hour interval and do the work.

BB7's have a whole host of issues that end users are not typically capable of sorting out. The fact that they are reliably mediocre, is because they have a very simple design that doesn't take full mechanical advantage of the system. It's much simpler to have a crummy system to start, still operating more or less crummy, then it is to keep a very good system in tip top shape. You notice the performance degradation quickly in a modern hydro setup.

Regarding your points about rotors being made to flex... just like you have no data to support that statement, I have no data to tell you that is incorrect. However, I completely disagree with your statement. The connection to automotive and motorscycles is moot because those systems utilize a single caliper, but a floating clamshell design which still allows the rotor to stay centralized, and the caliper to pull against them utilizing sliding dowel pins. Clamshell automotive calipers, do not flex a rotor to create friction against the pad material. Those systems do not work like bb7's at all.

We're well off the topic from the OP at this point. However, I cannot advocate using a substandard product because of believes or because the end user isn't capable of doing the proper maintenance on the product. Progress does not need to be stymied because the end user needs to be educated and do some work. We aren't still driving steam powered cars, or using land line telephones.

While I respect the underlying theme of this forum to buck bike industry standards and to go the collective own way... there are a whole host of reasons why current bike products are the way they are. They are now, leaps and bounds ahead of the original, older technologies. I will admit, that it's really 2015 and later products that had this reliability dialed. the truth of the matter is that very few people on this forum are using parts from the reliable age of bicycle products... which is why there is such a common theme of being dissatisfied with bike products for ebike diy usage here.
 
I have been considering "upgrading" my now BBSHD-powered trike to hydraulic disks, but am re-thinking it, mostly because what I have really works well. Good stopping power, relatively light lever pressure, infrequent adjustment or noise, and good pad wear.

This is on a 100-lb electric trike with a 240 lb rider. TRP Spyres, 203 rotors, two "front" brakes, no rear braking. I know among the advantages of the trike config is that the main stopping power, weight-forward, is shared by two front wheels/brakes, and the bigger rotors help. Also, both cables are short. The Spyres I have are "road" type and require levers designed for that cable pull rather than more common mountain levers used on trikes. The Spyres do press inwards on both sides of the rotors - which may or may not be a real advantage. I had BB5's on this thing with smaller rotors (pre-electric) and the stopping power was fine. I've had this set up for three years, and only on the second set of pads.

I would venture that big motorcycle disks/calipers function like automobile disks do - rather than distort the rotor like a flexible bike rotor, they press from the outward side only (in general) and rely on a floating caliper mount to allow the inward pad to be pulled toward the inner brake surface - the rotors are too thick to distort. Maybe some smaller motorbike disks work like the bike variety.

Regardless, I think the main advantage of hydraulic actuation is simplicity of cable/hose routing, along with efficiency of force transfer - both reasons why they are used on larger vehicles - but I will say that for bikes, even fast, heavy ones, good mechanicals are close in stopping power and sometimes simpler and more durable.

https://endless-sphere.com/forums/viewtopic.php?f=6&t=112009 - this when the trike was hub-motor driven, same braking setup. FWIW, I had regen braking enabled but found the tradeoff between strong stop and the tendency to torque-rotate the axle kept me from using it as an effective friction brake replacement.
 
ebbsocalMTB said:
Can't say I agree at all with mechanical disk brakes. they are pretty crappy and every one of them except for pauls or trp spyre have a moving caliper piston only on one side and the other is fixed. It's an inferior design to be perfectly honest. BB7's were some of the better ones at the time (this was pre trp spyre) but they are still shite in the context of modern brakes and have no place on machines where back country serviceability isn't the #1 build logic and priority.

Part of your problem is your technique. You say you're only using front brake because the back skids... This is from improper technique in general. you need to shift your weight back, balance the weight transfer as much as possible and use both brakes. If you have a totally crap fork that is under sprung or using elastomers, this is exacerbating the problem because you have needless weight shift to the front of the bike so I would suggest locking out the front fork. You should absolutely be able to do 35-40% of your braking work with your back brake. In times of absolute threshold, that number will drop to 20%, but only for brief milliseconds in the braking process.

300lbs of weight is a lot of weight, but it's not really much more then many dh and full enduro mtb riders. I ride with a guy that is 265lbs, 6'7" and he absolutely shreds on his 38lb enduro bike. He runs 220mm rotors and sram code rsc brakes, and he like me, rides downhill grades in excess of 20% often. his brakes get hot enough to smell hot, and make ticking noises when they are cooling off, but no fade and no damage to the system.

What shimano brakes do you have? Shimano brakes have a whole host of issues depending on generation. Many generations leading up to the m7xxx, m8xxx and m9xxx have issues with weaping lever seals, and also cracked and damaged ceramic and/or phenolic pistons. This would apply to M6xx, M7xx and m9xx. This is common and isn't necessarily due to heat, but rather due to just getting brittle with age. You can rebuild the calipers with new pistons and new seals, and right now with parts availability, that may be the better option.

Yeah the front fork is cheap. Can't lock it out. It's a sun tour.

I have m6120 shimano deores I bought from back country

https://www.backcountry.com/shimano-deore-br-m6120-disc-brake?CMP_SKU=SHIU1C8&MER=0406&skid=SHIU1C8-BLARES-FRO&mr:trackingCode=35EEB025-17ED-EA11-8116-005056944E17&mr:referralID=NA&mr:device=m&mr:adType=plaonline&CMP_ID=PLA_GMm001&utm_source=Google&utm_medium=PLA&k_clickid=_k_CjwKCAjwwsmLBhACEiwANq-tXELM92OOipUvFe4LYH3lt1C5LdZmKy8NaO7VhhTodaLoNdrFwrQlsRoC2TgQAvD_BwE_k_&utm_id=go_cmp-12868123420_adg-121976316672_ad-517539118271_aud-318683175335:pla-983202699017_dev-m_ext-_prd-SHIU1C8-BLARES-FRO&gclid=CjwKCAjwwsmLBhACEiwANq-tXELM92OOipUvFe4LYH3lt1C5LdZmKy8NaO7VhhTodaLoNdrFwrQlsRoC2TgQAvD_BwE
 
spinningmagnets said:
If the pads were rubbing, that will definitely build up some heat ahead of a hard stop...
..

Its super difficult to get it to stop rubbing completely. Every time I change a flat, take out the wheel, it needs re adjustment

It's a little tick tick tick sound.
 
ebbsocalMTB said:
-Use appropriate rotor sizes. There isn't a limit to rotor sizes on forks. You can have a crappy fork that is dangerous to begin with, which is likely because most ebikes come with some pretty shit forks, and a lot of teh forks I see used on this forum, I wouldn't touch with a 10' pole. however with the right adapter, any post or IS mount fork can support a 200mm rotor. I highly suggest 200mm minimum... I won't even ride my 25lb xc marathon bike without 200mm rotors.

I have 180 mm. I checked the specs for the fork and it's maxed out. I have an adapter on there too already, I.s. to post.

Probably not the best fork. Hmm where you get a affordable quality one
 
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