Disk Brakes

myideal

Hi,

Quick question as I can't seem to find the answer online so hoping someone here will know the answer (as I'm sure you will).

The disk brakes on the front of my bike have lost effectiveness and I have to pull really hard to get it to stop. Guessing it needs bleeding however is this jumping the gun and something more simple I should be doing first?

cooldad

If they are squidgy they may need bleeding.
Sounds more like the pads/rotors are contaminated. Clean the rotors with isopropyl alcohol and replace the pads first.

bbrap

If the levers come back further than they used to or feel squidgy they probably need bleeding. If they are biting at the same point they used to but just don't stop as well then contamination is probably the cause. How worn are the pads? some tend to go off a bit once nearly worn out, not sure why, maybe getting down to where the actual pad is bonded to the backing or something.

ugo.santalucia

People are obsessed with bleeding. Shimano brakes (assuming you have Shimano hydraulic) use mineral oil, in theory they will never need bleeding... I am not sure why they would need bleeding.

Since we are in the beginners section, it is worth asking: are your brakes actually hydraulic?

myideal

Yes they are hydraulic, I'm sure about that as it has the fluid holder built in to the leaver. I'll try the cleaning first as that sounds possible. I'm having to pull hard to get it to stop, which maybe means something is on the brakes. It also has a squeak when it's pulled hard ...not sure if that is the sign of something?

ugo.santalucia

myideal wrote:

Yes they are hydraulic, I'm sure about that as it has the fluid holder built in to the leaver. I'll try the cleaning first as that sounds possible. I'm having to pull hard to get it to stop, which maybe means something is on the brakes. It also has a squeak when it's pulled hard ...not sure if that is the sign of something?

Check your pads, they might be worn out... with hydraulics you don't realise it until they are gone

Dirty rotors is another obsession people seem to have. In 6 years I never had to clean the rotors. However, pads can get contaminated, but I would think wear and especially uneven wear is a stronger possibility

crossed

ugo.santalucia wrote:

People are obsessed with bleeding. Shimano brakes (assuming you have Shimano hydraulic) use mineral oil, in theory they will never need bleeding... I am not sure why they would need bleeding.

Totally agree with this. I actually think that half the problems people have with hydraulic disc brakes, especially MTBer's for some reason, are down to them making a mess of bleeding their brakes.

As you say though, it sounds like it might be contaminated pads. I've had contaminated pads a couple of times with the Shimano resin pads and they howl quite badly. Fresh pads and a quick wipe of the rotor with some brake cleaner and they're good to go again.

Apart from swapping pads, I find that the Shimano brakes are pretty much maintenance free.

bbrap

ugo.santalucia wrote:

People are obsessed with bleeding. Shimano brakes (assuming you have Shimano hydraulic) use mineral oil, in theory they will never need bleeding... I am not sure why they would need bleeding.

Totally agree, mineral oil being non hygroscopic they should not need to be bled unless there is damage to a seal, leak in the system or a component has been changed (I had to bleed mine when I changed a caliper to flat mount from post mount). A mate had a bike (mountain) which required regular bleeding, turned out to be an olive which had been damaged on installation (never did find out how, or he would not admit to having butchered it ). I would have expected to notice fluid (oil) somewhere near the hose/caliper junction but there was nothing evident so there are probably plenty of opportunities to mess things up for the ham fisted.

ovi

you can try a spray tin of brake cleaner from a motor factors or halfords.

ZMC888

bbrap wrote:

ugo.santalucia wrote:

People are obsessed with bleeding. Shimano brakes (assuming you have Shimano hydraulic) use mineral oil, in theory they will never need bleeding... I am not sure why they would need bleeding.

Totally agree, mineral oil being non hygroscopic they should not need to be bled unless there is damage to a seal, leak in the system or a component has been changed (I had to bleed mine when I changed a caliper to flat mount from post mount). A mate had a bike (mountain) which required regular bleeding, turned out to be an olive which had been damaged on installation (never did find out how, or he would not admit to having butchered it ). I would have expected to notice fluid (oil) somewhere near the hose/caliper junction but there was nothing evident so there are probably plenty of opportunities to mess things up for the ham fisted.

Yeah, but the oil gets dirty and old so the bleeding process needs to be done every year or so if you ride regularly. It's just the system gets contaminated with dirt and not air. The old oil certainly comes out darker and the lever is firmer after the bleed.

Vslowpace

It may be the pads are either worn or have some crud on them. There may be some air in the system, I found strapping the levers to the bars overnight would on occasion prove fruitful.

ugo.santalucia

ZMC888 wrote:

bbrap wrote:

ugo.santalucia wrote:

People are obsessed with bleeding. Shimano brakes (assuming you have Shimano hydraulic) use mineral oil, in theory they will never need bleeding... I am not sure why they would need bleeding.

Totally agree, mineral oil being non hygroscopic they should not need to be bled unless there is damage to a seal, leak in the system or a component has been changed (I had to bleed mine when I changed a caliper to flat mount from post mount). A mate had a bike (mountain) which required regular bleeding, turned out to be an olive which had been damaged on installation (never did find out how, or he would not admit to having butchered it ). I would have expected to notice fluid (oil) somewhere near the hose/caliper junction but there was nothing evident so there are probably plenty of opportunities to mess things up for the ham fisted.

Yeah, but the oil gets dirty and old so the bleeding process needs to be done every year or so if you ride regularly. It's just the system gets contaminated with dirt and not air. The old oil certainly comes out darker and the lever is firmer after the bleed.

I would be very worried if dirt was allowed into the hydraulic system. If dirt gets in, certainly water gets in too. DIscoloured oil probably means something in the pipe or reservoir or piston has leeched a bit of oxide or else, I don't think it's dirt from the outside. It also doesn't mean the oil is no longer doing its job.

Given the average operating life of these groupsets, I very much doubt they need bleeding... if you keep them for 10 years, then maybe...

ZMC888

ugo.santalucia wrote:

ZMC888 wrote:

bbrap wrote:

ugo.santalucia wrote:

People are obsessed with bleeding. Shimano brakes (assuming you have Shimano hydraulic) use mineral oil, in theory they will never need bleeding... I am not sure why they would need bleeding.

Totally agree, mineral oil being non hygroscopic they should not need to be bled unless there is damage to a seal, leak in the system or a component has been changed (I had to bleed mine when I changed a caliper to flat mount from post mount). A mate had a bike (mountain) which required regular bleeding, turned out to be an olive which had been damaged on installation (never did find out how, or he would not admit to having butchered it ). I would have expected to notice fluid (oil) somewhere near the hose/caliper junction but there was nothing evident so there are probably plenty of opportunities to mess things up for the ham fisted.

Yeah, but the oil gets dirty and old so the bleeding process needs to be done every year or so if you ride regularly. It's just the system gets contaminated with dirt and not air. The old oil certainly comes out darker and the lever is firmer after the bleed.

I would be very worried if dirt was allowed into the hydraulic system. If dirt gets in, certainly water gets in too. DIscoloured oil probably means something in the pipe or reservoir or piston has leeched a bit of oxide or else, I don't think it's dirt from the outside. It also doesn't mean the oil is no longer doing its job.

Given the average operating life of these groupsets, I very much doubt they need bleeding... if you keep them for 10 years, then maybe...

I've been using the Shimano SLX 666, XT 785 and Deore hydraulic brakes on three different MTB's for probably over the last 5 years. I also used Avid/SRAM Elixir brakes for a few years before that. The XT 785 seem 90% the same as road brakes certainly at the caliper.

I have bled all these brakes and the Shimano brakes do get contaminated over a year or two of constant use. They are very reliable, barely had any problems but the oil does discolour, and it's been every time, bleeding is easy.

Nothing wrong, Shimano even say the oil will get discoloured over time and to bleed it with a compete system flush. It's not every ten years though! I've been neglecting my commuter MTB really I should give them a bleed to get them back to perfect condition, but they are only slightly spongy and perfectly safe around town, although if I was riding down a mountains I would certainly replace the oil.

myideal

Thanks. I knew there would be more basic checks to do first. Now I've got to work out how to get the pads out - suspect it's linked to the two allen keys that seem to be on the bike.

cooldad

ovi wrote:

you can try a spray tin of brake cleaner from a motor factors or halfords.

Don't do this, stuff is designed for car brakes, and contains additives often oil based, which work much harder at much higher temps than bike brakes, so stuff gets burnt off.
If the rotors need a wipe, use plain water or isopropyl alcohol, which won't do any harm, even if they don't need it.

ugo.santalucia wrote:

myideal wrote:

Yes they are hydraulic, I'm sure about that as it has the fluid holder built in to the leaver. I'll try the cleaning first as that sounds possible. I'm having to pull hard to get it to stop, which maybe means something is on the brakes. It also has a squeak when it's pulled hard ...not sure if that is the sign of something?

Check your pads, they might be worn out... with hydraulics you don't realise it until they are gone

Dirty rotors is another obsession people seem to have. In 6 years I never had to clean the rotors. However, pads can get contaminated, but I would think wear and especially uneven wear is a stronger possibility

I agree, but people seem to enjoy spraying random censored neat their brakes, be it WD40, chain lube etc.

As a 99% of the time mountainbiker, I agree with the rest though. Been using hydraulic brakes for many years, and none have ever actually needed bleeding. (All various ages and types of Shimano, I broke my single set of non shimano before they needed anything).

If I have to change hose lengths or something when swapping them around I'll normally run fresh fluid through until it looks clear.

ps brakes make screechy noises sometimes. I find riding through water, thick mud, sand, hosing them down, hard braking, gentle braking, no braking, swearing (delete as appropriate) sorts it out.

I fitted a set of qlmost 20 year old Magura rim brakes to an old Kona a year or so back, which had lived in a box for 15 years. New pads and they worked as good as new (mineral oil).

cooldad

myideal wrote:

Thanks. I knew there would be more basic checks to do first. Now I've got to work out how to get the pads out - suspect it's linked to the two allen keys that seem to be on the bike.

Step away from the machine, and do some more research. A couple of those allen BOLTS split the calipers, then you'll have fun and games.

If Shimano there'll either be a small allen bolt (XT upwards and a rubbish idea) or a split pin to remove them.

cooldad

And just noticed I'm in the road forum, so I have no idea what black magic may be involved in road calipers.

myideal

Are yes now one has on the back like a split washer that goes around it. Would that be most likely the one that is holding them in place?

I'm very much in the world of ask, check, ask again (if unsure) then do. Never dive in as you can make some serious censored ups.

cooldad

Yep, that would be the pad retaining pin - with a small circlip. Even a dumber idea than the scew in tiny bolts. Lose the circlip and braking is somewhat compromised. Seen it happen once or twice when people have changed pads on the trail.

myideal

Probably silly question, but does this just fall off as I unscrew the bolt or do I have to fiddle with plyers to remove it first?

frisbee

You have to remove it first.

There are some pretty good service manuals for Shimano stuff or various guides on youtube.

I would recommend not fiddling around with brakes unless you have some basic understanding of what is what.

ZMC888

myideal wrote:

Probably silly question, but does this just fall off as I unscrew the bolt or do I have to fiddle with plyers to remove it first?

For heaven's sake watch some Youtube tutorial videos! :shock: :shock:

https://www.youtube.com/watch?v=Lbi1HQMQIBo

crossed

cooldad wrote:

Don't do this, stuff is designed for car brakes, and contains additives often oil based, which work much harder at much higher temps than bike brakes, so stuff gets burnt off.
If the rotors need a wipe, use plain water or isopropyl alcohol, which won't do any harm, even if they don't need it.

That's nonsense.
The brake cleaner you buy for your car is the same stuff as the stuff you pay 3x more for in a bike shop.
I've been happily using Wurth or Pagid brake cleaner for years with no issues whatsoever.

cooldad

I don't pay anything at the bike shop. It's unnecessary.

I'll stick to IPA if I need to clean stuff.

homers_double

Was on holiday with the bike over summer and the brakes started squeeling massivly, cleaned the rotors with Gin and scuffed up the pads. Problem solved... for about two miles.

cooldad

If you'd just drunk the gin instead you'd stop worrying about the squealing and sing along.

bbrap

cooldad wrote:

I don't pay anything at the bike shop. It's unnecessary.

I'll stick to IPA if I need to clean stuff.

Just make sure its Isopropyl Alcohol and not India Pale Ale :P

hsiaolc

myideal wrote:

Hi,

Quick question as I can't seem to find the answer online so hoping someone here will know the answer (as I'm sure you will).

The disk brakes on the front of my bike have lost effectiveness and I have to pull really hard to get it to stop. Guessing it needs bleeding however is this jumping the gun and something more simple I should be doing first?

Well not sure why you thought about bleeding in the first place.

Firstly I think it is good that you try to learn and service your own bike but it takes time so be patient.

I service my own cars so servicing my bike is the only way to go but there are a few times I needed to take it to the professionals.

With regards to your brakes I think it is likely 1. You have no more pads left (very likely if you never changed one) 2. You've contaminated with some lubrication.

Check with pads first. Look at youtube and figure out if your pads need changing.

If yes then try that first. At the same time clean your discs with brake cleaner. Any brake cleaner will do.

It should solve your problem. If not please take it to your LBS to get it looked at and fixed.