Erlstn

Do hydraulic brakes rub all the time and sound gritty? I have adjusted and had lbs do two adjustments and I've owned the bike for a month. If this is what hydraulic brakes are like, I am going back to linear. Any thoughts?

FBinNY 

First of all, I'm not a disc brake fan so not a likely apologist for them.

But your brakes shouldn't rub at all except when you apply them. The key is to make sure that they are perfectly squared up and centered over the disc. There are various methods, but mine is the simplest. Loosen the mounting so the caliper can float, apply the brake so it clamps itself to the disc, but not so tight that it can't slide a bit. Now tighten all the mounting bolt while keeping the brake applied. When your finished, both sides should open equally when you release the brake.

Other issues can include a warped disc which needs more caliper clearance than your brakes are designed to provide, and on some brakes a mounting system with limited float, especially angular float. A rigid mounting system will cause the brake to align according to the mounts, and if they're not perfectly square to the plane of the disc, it'll be hard to cure rub. I fix these with a file, and you might have to also, but that's exacting work and you might want to think long and hard before going that route.

RandomEncounter

No, they don't, although you may hear some of before the pads have been broken in. Have you only tried one LBS? When I had issues with mine I took it to a mechanic that hadn't worked with hydraulic disc brakes before and made the situation much worse. A different repair shop that has a great rep in my town fixed them.

Try adjusting the pistons following the instructions in the manual, also make sure your pads are clean. Also check that the disk isn't bent. This is easiest to see when the wheel is spinning.

Canker

Of coarse not. You know there are many manufactures of hyd disk brakes for bikes and some are crap and some are awesome. You didn't tell us what brand they are or even what kind of bike they are on.

Erlstn

True...they are tektro aurigas. I have only tried the lbs that I bought the bike from (Raleigh Tokul 2). Thanks for the responses - I had already done the loosening, squeezing, and tightening thing and still had slight rub. Dont see any bend in the disk...maybe just needs more break-in time

Andrew R Stewart 

I will take a different view here. Should disk brakes rub? No. when riding in a straight line and applying even pedaling pressure. But when cornering or putting the pedal to the metal it's not un common. What is the issue is that the clearance between pads and rotor is far less the rim and pads. Less then the added lengths involved, axle to pad contact points. This is why all the new axle/drop out standards are changing. The old standard od a 9 or 10 mm axle with a QR having a 5mm shaft diameter was plenty stiff enough for the caliper/canti/V brake pad and rim gaps when stresses flexed forks and rims. But now that those pad/rotor gaps are so much less a stiffer axle/frame design is needed.

Hydraulic lines only make the initial squeeze smoother and the modulation better, nothing to do with the pad/rotor gaps. The closer gaps and the resulting rub when the system isn't stiff enough is part of the industry learning curve. That our engines are only a half horse power or so make this rub less acceptable.

So the current answer to your real future is to get a bike with stiffer wheel/frame/caliper interfaces, and live with the results. Andy.

Canker

If there is a slight rub in a certain spot when you spin the wheel and aren't touching the brake lever then yes there is a bend in the rotor. My latest used bike came with Sram bleh hyd brakes and when I put it together they rubbed like crazy no matter how many times I did the loosen the caliper and squeeze the brake lever trick. What you have to do is just slowly spin the wheel and listen/look for where the rub is and hand bend the rotor away from the pad. Then you may have to do the tighten and loosen caliper trick again. I don't know if some brake manufactures have tighter pad to rotor tolerances than other or what but I could never get all the rub out on the Srams, with shimano I don't have that issue. Anyway a tiny bit of rub isn't noticeable when actually riding on the trails. Sometimes you just have to get over it and ride.

Looigi

When they're working right, they're great, but there are lots of little things that can go wrong or need attention. Some basics: Disc must be true. Calipers must be aligned correctly and centered laterally with respect to the disc. Brakes should be bled with the pistons fully retracted (using a bleed block is best). New pads need to be bedded in. Pistons are retracted by the elasticity of square cross-section o-ring seals, so pistons and their bores need to be reasonably free of dust or grit. If they're not retracting from contact with the disc, the pistons need to be reset (pushed fully inward) and may need to be cleaned. Discs and pads need to be kept absolutely free of any oil or grease. If contaminated, discs can be cleaned, but pads (mostly) not.

davidad

[QUOTE=Erlstn;18411598]True...they are tektro aurigas. I have only tried the lbs that I bought the bike from (Raleigh Tokul 2). Thanks for the responses

I put together a trike for a friend and had trouble with one of the disc calipers. After many tries using the squeeze the lever method removed the caliper and using a flat sharpening stone ground the mating surfaces of the bracket and caliper flat. That solved the problem.

fietsbob

Tektro Aurigas , You buy them separately or were they part of the OEM pick when you bought the whole Bike?

( I looked up specs , they were the stock part (chosen to get the whole bike cost down to where you thought it affordable) )

There are nicer Discs than the Auriga.. but they will cost more $, too..




I'm Ok with my Hydraulic Magura rim brakes & BB7 discs ... they were both OEM picks ..

Though the Discs were a part of someone else's Custom Pick. (at Bike Friday, You have choices)





Avid mechanical discs Though working good, BB7, can be abused , mountain biking ..

In the shop I've seen the outer plastic knob .. you use to adjust the pad clearance for wear..

getting hot enough dragging the rear brake on descents , to get hot enough for the plastic to melt/distort..

dabac

I've never had much luck with the loosen-squeeze-tighten procedure. IME the caliper will just about always shift as the screws are tightened down.
I prefer to loosen the screws just enough so that the caliper can be shifted around using firm thumb pressure or gentle taps with a screwdriver handle or similar. I'll set the gap, then tighten screws alternatingly while monitoring that the gap remains intact.

fietsbob

Loosen squeeze and retighten works well with Avid's brakes, because they mounted them with Domed and cupped washer pairs*

that self center at various angles , then while gripping the disc you tighten the post mount bolts ..

* these are used to mount V brake pads to the arms, by the millions..

cruiserhead

Try some of these videos- I've found them to be really good
https://www.youtube.com/user/globalc...ake+adjustment

dabac

I've never had much luck with the loosen-squeeze-tighten procedure. IME the caliper will just about always shift as the screws are tightened down.
I prefer to loosen the screws just enough so that the caliper can be shifted around using firm thumb pressure or gentle taps with a screwdriver handle or similar. I'll set the gap, then tighten screws alternatingly while monitoring that the gap remains intact.

FBinNY 

We all use a variation on the self-centering on the rotor method. I agree that some brakes will move as tightened, so I apply enough brake force to position them, then as I tighten the mounting bolts, I might use a bit of body checking to nudge them back to center before fully tightening.

But as others have pointed out, there are two other key considerations besides a spot on mount. The disc must run true because there's not much wiggle room at all, and the brake system must be bled of ALL air because air in the lines reduces travel and will reduce the disc clearance when open.

FWIW -0 as I mentioned, I'm not at all a fan of disc brakes, especially for road and hybrid bikes, because they introduce more problems (and costs) than they solve. I come from the simple is better school of design, and no braking system is simpler than your basic caliber brakes, which have a major advantage in that the rotor is truable. But that's just me, and others will disagree. I only mention it so the OP knows I wouldn't defend discs if I didn't think they could be made to work.

ltxi

x2...

Canker

a disc brake rotor is truable too and easier since you don't need any tools. They do make tools for it though if you want to get all fancy.

https://www.amazon.com/Park-Tool-Roto.../dp/B00781WXW2

catgita

Nobody addressed the gritty sound. I have owned 3 very different MTB style Hydros, and Avid 7s. All have made unpleasant metal on metal type sounds, like fingers on a chalkboard. Off road I am fine with it. On the road, yuck. The more perforations in the rotor, the worse the sound. Hard to beat the silky sound of rim brakes.

FBinNY 

The difference is that wheels are relatively easy to true to great and controlled precision, far greater than what's needed for good brake performance, while disc brakes call for greater precision, and discs are harder to get that close.

Also we would true our wheels anyway, and still need to even with disc brakes. So having to true a disc is an extra task no matter how easy (or not).

Canker

If you cared enough to setup a dial gauge or something it really wouldn't be that hard to perfectly true a rotor. I'm sure there are youtube vids out there showing how to do it to perfection. Not really anymore effort that getting a really true wheel and probably easier once you have a setup to do it. I just don't care that much because like I said in my earlier post about mine that got bent a bit in shipping it doesn't matter if there is a slight rub when out on the trail. I just do it by ear and eye with the wheel on the mtn bike. We are talking about mtn bikes here and who really wants to go back to rim brakes on those? You want to talk about annoying noises and problems. My first mtn bike with rim brakes screamed most of the time because of grit and mud always being on the wheels and that isn't even talking about how much better the disc brakes work and feel. Now road bikes I can understand if you prefer rim brakes.

Avid/sram disc brakes have always been known for being noisy. I have them on 2 out of my 3 mtn bikes though and they are actually fine. On my bike with shimano brakes the front did start squealing recently, think the pads got contaminated, and after I replaced them with organic pads back to quiet. Usually when I have had a squealer I just clean everything and it quits.

Bike Gremlin

I would never put disc brakes on my bicycle, not a fan of those, for several reasons. HOWEVER: hydraulic disc brakes are the best brake system available today - for cars, motorcycles and bicycles. Good quality, well set up hydraulic disc brakes shouldn't rub. The should provide good stopping power in all the conditions (hot, cold, dry, wet, muddy). What's very important: they provide best modulation!

For your problem:
Are your brakes high, or low end? If it's a cheap, low end model, they will probably never work too well. Good V-brake, or caliper brake system is about 70 euros (brakes, levers whole set), while a good hydraulics will cost around 150 euros (in Europe) for a quality set.

Make sure calipers are clean. Give the brake pads some time to bed in - a few hard brakes (with all precautions taken), from high speed should do the job. The wheels should be securely fastened to the frame, make sure they are seated in the dropouts all the way, with a firm grip on quick release levers (don't over do it).

This could help:

Olefeller77 

These are the brakes that came on my Trek Marlin 6 when I bought it new in 2015. I have given it a lot of use and the brakes are smooth and never a bit of problem. I checked the pads today and they are E10-11 ceramic. I ordered a new set of pads today to have on hand but original ones seem to have a lot of life left. I am impressed with my Tektro's.
I tried a local Trek shop for the pads but they said they can't get them. ( Amazon to the rescue. )

TiHabanero

There are a million influences on disc brake rub. Tru of the rotor, square of the caliper mount, rotor thickness, clearance between rotor and pads, properly functioning caliper or plunger at the lever, hub/axle flex, etc. etc. etc. Everything must be looked at as a potential cause. Most of the time when I have a completely uncooperative hydro system regardless of brand, the caliper has to be positioned manually as noted in previous posts.

While you all fiddle with your disc brakes, I will be out riding with trouble free and proven rim brake technology. .

shelbyfv

Well, OP is no longer "new" to hydraulic discs.... Hopefully he got them sorted.