What are the benefits of disc brakes over rim brakes?
 

• All-weather performance (little or no change due to water, mud, ice)

• Low maintenance (setup calipers once & forget)

• Long pad life

• More stopping power for less effort (less forearm “pump-up” on long down hills)

• More control - better modulation (smooth grab-free power application and less wheel lock-up)

• No more worn out rim sidewalls

• Can knock a wheel out of true and still ride, with no effect on braking.

•  More mud clearance (those who ride in mud and leaves know what that means!)

Do I need disc brakes?

No, not unless you have issues with rim brakes in general or your rim brakes in particular.  Some people are quite happy with their rim brakes and others  find that because of their riding environment (terrain and conditions) that rim brakes don't do the required job.  You will find that as your terrain gets steeper and your conditions get wetter, disc brakes become more useful.  Also some of us live in fairly flat, dry areas and we don't actually need disc brakes all the time but we want them for the times we do travel to steeper and wetter areas.  Just don't get caught up in it - unless you want to, or need to of course.   If you’re a heavy rider (200 pounds or more) you will certainly benefit.

What’s the best disc brake?

There is no generic "best" disc brake for everyone.  There is probably the best brake for you and you will have to research your wishes and needs and then cross-reference them against what's available.  All brakes have negatives & positives compared to other brakes but just make sure you're not listening to unfounded fear-mongering or innuendo.  For instance, cables don't stretch and seize up, hydraulics don't leak all over the place, heavier cable disc brakes won't make you the slowest rider and featherweight hydraulics won't make you the next world champion.

You should research all the brakes carefully by reading and talking to people.  Just be careful that untruths don't cloud your judgment.  Look at mtbr.com Product Reviews to see what real people say about the brakes you've heard about.  Also be careful that their poor mechanical skills are not the cause of their dissatisfaction.  A lot of people cause their own problems. There aren't many bad brakes out there right now.

Test ride as many brakes as possible if you can but remember a bike from a shop will not have brakes that are bedded in, so they may not be as powerful as they should be.

Are disc brakes better than rim brakes?

Usually our braking performance is limited more by the friction between tire and trail than by the friction between pad and rim.  If we can lock up a wheel, then locking it up using less power is hardly much of an improvement.  But the gain here would be during long descents where less finger pressure would lead to less arm strain.  With disc brakes the maker gets to make the whole package - pads, rotor, lever, cylinders - so they can engineer them to compliment each other with minimum compromise.  The limiting factor with rim brakes has got to be the soft alloy rims and pads that surrender stopping ability because of their needed softness necessary to prevent damage to these rims.  Another limiting factor is their closeness to the water and mud that we ride through.

But we do find that power, modulation (smooth application of that power), longevity, adjustability are generally better with disc brakes.  Disc brakes suffer far less than rim brakes in poor conditions.

Will disc brakes fit my bike?

This is probably the most confusing aspect of disc brakes.  Brake companies have been arguing and disagreeing and even sometimes agreeing about brake mounts since Day 1.  We will try to remove some of the mystery here. 

Let's look at front mounts first - the ones at the bottom of your left fork leg.  It doesn't matter if it's a rigid or suspension fork.  On the left we have the most common mount out there - the International Standard (IS).  On the right is the Postmount that you will find on Manitou forks.  Most front brakes can be bought in either IS or Postmount models.  You must know which type you need before you order your brake.

The IS on the left uses shims for caliper alignment (to the rotor) and the Postmount on the right uses elongated holes.  The Avid cable disc brake uses it's own method - CPS - Caliper Positioning System - a system of two bolts with cupped washers.  The Avid CPS system is very close to being a combination of both the mounts shown here.

IS Mount 51mm	Postmount
IS Mount 51mm	Hayes Mount

Then there are mounts on the rear of the frame.  The most common are the IS (International Standard) as shown on the left.  On the right is the Hayes mount.  The rear IS system again uses shims for alignment and the Hayes uses elongated holes in the caliper.  Also there is the Trek Disc-o mount that, with adaptors, will take either IS or Hayes calipers -

Even the IS standard changed in the year 2000.  The distance of the disc mount face from the center of the hub changed which moved the disc towards the fork leg or rear stays.  Pre 2000 calipers will not fit the post 2000 hubs.  Be careful if you're buying used or old stock brakes from e-bay or bike shops.

Do disc brakes need a lot of maintenance?

Almost none.  Pads last a long time and are usually much easier to replace than rim brake pads.  Most disc brake are now self-adjusting but even cable disc brakes (all cable disc brake are manual adjust) take but seconds to adjust and without tools.  Bleeding hydraulic brakes scares a lot of people but it takes a few minutes at most and it certainly isn't a regular maintenance issue.  Bleeding is only usually performed when hardware is changed.

Initial setup takes the most time and should be done as perfectly as possible as it affects brake performance greatly.  As initial setup is a one-time deal - and doesn't change as pads wear or are replaced - then the time spent is important.  Some brakes take longer than others to set up - the ones with shims take the longest, the Avids with their CPS (caliper positioning system) are in the middle and Formula Activa with their sliding caliper are the quickest but, as said before, it's time well spent.

Are disc brakes heavy compared to rim brakes?

Yes & no.  Some of the ultra light disc brake sets rival, or beat, v-brakes for weight.  For instance, a whole complete set of Formula B4SL (world's lightest) weighs only 630g complete compared the XTR at about 690g.  Yes, some disc brakes are heavier than v-brakes but disc brakes give (for most people) so many benefits that any extra weight is immaterial.  It's like fat tires and shock forks - we get so many benefits compared to skinny tires and rigid fork we stopped asking the same questions about them years ago.  Of course disc brake hubs are going to be heavier than non disc brake hubs.  Here are some examples -

        Shimano XT - +89g per set

        Chris King ISO - +120g per set

        DT-Swiss 240 - 111g per set.

        Weight sources - Speedgoat.com, Chris King, DT-Swiss.
 

• One of the most popular disc brakes (the Avid cable disc) is also one of the heaviest - 1057g for a whole set (SD7 levers, cables, brakes). 

• A set of 2002 Magura Martas (747g) weighs almost 100g LESS than a large full waterbottle (836g).

• A set of Formula B4SL (630g) weighs 206g LESS than a large full waterbottle (836g).

• A set of Formula B4SL (630g) weighs about the same as a small full waterbottle (638g).

• 9 Clif bars weigh the same as a set of Formula B4SL.

• Shimano XTR v-brakes (BR-M951), Avid levers (SD7) and cables (est 100g) weigh 696g.

• NOW can we stop asking about weight!

• Weights sources - Mike T.

Where do I find information for my brakes?

There are three ways - all brake makers have web sites where you may find the information; all brakes (unless you bought them on a bike) come with a manual or you may contact the brake maker and ask for a manual.
 

Can I have a front disc brake and a rim brake on the rear?

Many people have no rear disc brake mount but have disc tabs on their fork.  Yes it's better to have a front disc brake than none at all.  And really, the front is the best place to have a disc, or more powerful brake.  As weight is transferred forward under braking, the front wheel does about 70% of the work of stopping the bike.

There are many bikes, even some factory bikes, that have a disc brake on the front and a rim brake on the rear.  But then you must realize that all the good reasons for having a disc brake will not apply to ½ of your braking system.  But it's better to have some benefits of disc brakes than none.

There are adaptors available that might allow you to mount a slave cylinder onto your otherwise mountless rear dropout.  Here are two versions -

Picture courtesy of Hammerhead Adaptors - http://www.geocities.com/racing_green_uk/

Picture courtesy of Therapy Components http://www.therapycomponents.com

  

        Equipment  Back to Top»

What do I need if I want disc brakes?

You will need the brakes themselves of course, as well as wheels that are compatible with disc brakes - meaning the hub has a place to bolt the rotor to. If you’re using hydraulic disc brakes, they’ll come with hydraulic hose and dedicated lever assemblies. If you’re going with cable-actuated (“mechanical”) disc brakes, you’ll need new (longer) cables and housings too.  You may be able to use your old brake levers. Cables for mechanicals don’t have to be high end, but don’t get cheap with them.  You’ll want to run full housing, so take that into account when you buy your cables.

First Principles Performance products makes an adaptor that can alter some existing hubs to be disc-compatible, but the wheel will still need to be rebuilt with different spokes on the disc side. BUT, it means you won’t have to trash your old high-end hubs. It should be noted that it’s a permanent alteration, as the hub flange has to be drilled out to accommodate fixing screws.  Most people will go with a new disc specific hub rather than take this step.     
They have been tested on the North Shore and have held up well, they are not available for all hubs though. If you happen to own Chris King hubs you can send them back to Chris King and for a price they will make them disc compatible (new shells).

You will need to make sure that the disc mounts (if you have them) on your frame are compatible with the brakes you intend to buy.  Some companies such as Rocky Mountain and Specialized do make disc brake adapters for some their bikes, others may as well and you will need to check on availability.
Your fork will have to be disc specific too and the type of mount (IS or Postmount) will have to match the brake you buy.  The rims should be disc compatible (but not necessarily "disc specific") as well…. More on that in the next question.

Do I need heavier rims & spokes?

Not unless you're going all-out into DH or FR.  For XC riding, normal weight rims and spokes work perfectly well.  For normal purposes, rims and spokes that are fine for rim brake stresses are adequate for disc brake applications too - 400-500g rims, 2.0/1.8/2.0 spokes, x3 lacing.

There are disc specific rims (no sidewall brake track) and some RIM brake rims are fine for disc brake usage also.  As there ARE more stresses on rims used with disc brakes, rims with reinforced spoke beds are advisable to prevent spoke nipples from cracking the rim eyelets.  As it's almost impossible to know which rims are reinforced and which aren't, it's easiest to refer to manufacturers' websites to see if there are warnings issued for your rim of choice.

Why larger rotors? 
 

This is a common misconception. Disc brakes drag as much as any other brakes that are poorly setup. They do not normally produce any drag unless    installation, setup or adjustment is incorrect. Refer to the factory manual for your brakes to find out how to perform these steps correctly.
There is one disc brake that is supposed to drag and this is due to its design. This is the Magura GustavM and it's a dedicated DH racing brake. The slight drag does not slow the bike down at all.  Note from Pat T who uses Gustav: The drag is hardly noticeable at all, sometimes you will hear the noise but mostly you won’t be aware of it.

Is there a cure for broken levers?

Yes possibly there is!  Brake levers really aren't designed for hitting trees or the ground but this IS mountain biking so it's going to happen sometime.  You can easily lessen your chances of a broken lever blade or lever body by leaving the handlebar clamps a little loose so when the lever hits something it has the chance to swivel around the bars instead of taking the whole force.  Tighten the lever clamp just enough so you can pick up the front of the bike with the lever bodies without them moving.  Check this often and adjust as necessary.

 Operation      Back to Top»

Cable & Hydro disc brakes - how do they operate?

Disc brakes, both cable and hydraulic both work on the same basic principle of a lever transmitting force through a connecting link (a wire cable or a tube filled with fluid) which exerts pressure on a pair of brake pads which in turn clamp a rotating disc that is attached to the wheel's hub - just like the family car.

As total weight has to be an important factor with bicycle disc brakes, their manufacturers have to be very creative with their design while having to work within some limiting factors.  Hydraulic brakes work on the principles that fluids are not compressible and that fluids pressurized in a closed container transmit forces equally in all directions.  Cable disc brakes work much the same as cable rim brakes but with exceptions that we will see later.

This is how hydraulics work - a pull on the lever blade exerts pressure on a piston in a master cylinder (inside the brake lever).  The piston then pushes on the oil in the brake line and the pressure travels down the line to a "slave" cylinder (or caliper).  In the caliper are housed anywhere from one to six small pistons.

The pressurized fluid forces the pistons outwards which move a pair of brake pads.  They in turn clamp the rotating rotor which is bolted to the wheel's hub.  Three makes of disc brake use only one piston to apply the pads (Avid cable disc, Hayes cable disc and the old pre-2002 Magura Louise).  This single piston pushes on one pad and one side of the rotor only.  As rotors are 2mm thick and quite flexible, the rotor flexes sideways when touched by this pad and contacts the fixed pad (non moving because it has no piston!) on the other side.  Consequently the rotor gets squeezed between the two pads.  This idea is quite ingenious and very effective.

There are two other brakes which have moving pistons only on one side - the Magura Gustav and the Formula Activa - but instead of the flexing rotor they have a sliding caliper which moves sideways as a reaction, thus pulling the fixed pad onto the back side of the rotor.

The makers of the brakes have to contend with three things that happen to all brakes - pads need "retracting" after use, pads wear and fluid gets hot and expands.  Here again they use methods that are the same as in the family car.  They use an ingenious method of pad retraction and self-adjustment; for expanded fluid they use a reservoir.

Retraction works like this - the caliper piston is sealed by a seal with a rectangular cross section.  When the piston in the caliper is applied this seal tends to "stick" to the piston and it deforms sideways as the piston moves.  When we let off the pressure in the brake, the seal wants to regain its old shape and it retracts backwards and drags the piston with it!  Very ingenious!  Here then we have pad retraction without the use of springs.

Self adjustment works like this - when the pad material wears down the piston has to travel a bigger distance to apply the pad.  As in the previous phase, the piston moves sideways and flexes its seal as it goes.  The seal is designed to flex sideways just so far and no further.  As the piston now needs to travel more than it did before (our pads are worn remember!) then the seal soon reaches the limits of its elasticity.  The next step is almost magic - the piston now slides through the seal allowing the worn pad to contact the rotor.  As we release the pressure inside the brake the seal retracts pulling the piston back as before but only enough to remove the pad from the rotor.  Here we have self-adjustment without any levers, links or screw threads!

Hot, expanded fluid, if left to itself would slowly but surely apply the pads to the rotor.  This problem is dealt with by a reservoir and as we release the brake lever, the retracting master cylinder piston uncovers a port into the reservoir.  The extra fluid can now expand into this reservoir where it cools and contracts.  When we next apply the brakes the piston seal covers the port thus trapping fluid in the line and creating a "sealed system".

As all pressurized fluids respond to the same laws of physics, the brake engineers can take over at this point.  They have full control over system pressures, mechanical advantage (leverage) and piston travel.  They tailor master and slave cylinder piston diameters relative to each other to give the necessary leverage ratios and therefore pad pressure.

Cable disc brakes work in a similar fashion but with many differences due to the different method of force transmission.  The brake lever pulls a wire cable through an outer casing just the same as rim brakes but what happens at the caliper end is different to both rim brakes and hydraulic disc brakes.  The wire cable at the caliper end is clamped to a lever or actuating arm of the caliper.  This arm operates a coarse screw type mechanism which is linked to a "ball and ramp" mechanism within the caliper.  As the brake lever is applied the ramps move and the ball bearings are forced up the ramps pushing them against the pad's piston.  This of course applies the pad to the rotor.

Cable disc brakes only have one operating piston and thus need a mechanism for applying the opposing pad.  Avid and Hayes use the "flexing rotor" principle and Formula Activa uses the "sliding caliper" method.  As cable disc brakes have no "deforming seals" for self adjustment and pad retraction they have to rely on manual adjustment - knobs in their case - to adjust for pad wear and springs to retract the pads.

How do I install, set up and adjust my brakes?

Rather than typing out a whole set of instructions for everyone's brakes please refer to the website of your brake's maker.  They have all the latest updated information for your brakes.

What should I check on my brakes on a routine basis?

• Check the hydraulic connections and pistons for leaks.
• Check cables for fraying or sticking.
• Check lever pressure point with both hydraulic or cable brakes. The lever must not touch the bar under hard pulling! Adjust or bleed the brakes as necessary.
• Check for sufficient braking power. Your pads and rotors could be contaminated with oil.
• Check pad thickness.
• Check rotor warp. Instructions for fixing this are in this FAQ.
• Check rotor bolt tightness. Loctite those bolts and check torque if you have a torque wrench.
• Check caliper mounting bolts. You may Loctite these too.
• Check your wheel quick releases for tightness and proper installation.

Why do my brakes squeal and how can I fix it?

First and foremost there is NO disc brake which NEVER squeals and NO disc brake type which ALWAYS squeals.  Also there is no specific area where brakes have more problems. From super dry Scottsdale Arizona to wet Seattle there will be a few screaming brakes in every area of the country. Some brakes seem to have more problems than others but in general it's one of the following :

• Dirty ( oily ) rotors - clean thoroughly with Isopropyl Alcohol
• Dirty ( oily ) pads - clean with Isopropyl alcohol, then use emery paper and scuff the pads. Remember they need to be newly bedded in, so the first stops are not what you expect. If braking power is drastically reduced, replace pads with new ones.
• Loose rotors and loose calipers - tighten them up.
• Loose cones in the hub - again tighten them.
• Loose spokes - sometimes you can detect this if you rub a little grease exactly where the spokes are crossing/touching each other. If the noise changes, then you need to retighten the spokes.
• Loose quick-release - especially on alloy dropouts the q/r sometimes works itself into the alloy, the tension gets less and the axle starts vibrating.
• Loose suspension bolts - seems to be a problem on the older I-drive bikes, but not only them. Check the owners manual for proper torques.
• Loose Headset - adjust to specifications.
• Loose .... loose... loose ANYTHING. Yes even a loose saddle can make a noise if vibrated by the brakes.
• Incorrect alignment - use a Gnann-o-mat or Hope Spot tool to machine the tabs or use the CPS on Avid brakes.

My brakes fade and run out of power.  Why? 

This happens to brakes that are being made to perform more work than they are designed for. Braking produces heat and if the mass of the pads, rotor and caliper can’t dissipate this heat into the atmosphere quickly enough, the surface of the pad starts to give off gas or melt. This lubricates the frictional surfaces thus reducing the co-efficient of friction and the braking power.

Excessive heat can also boil the brake fluid which will turn any water to steam (most brake fluids absorb some water) and the gas produced is compressible so a spongy lever will result.

Choose brakes carefully for their intended job. After all we wouldn’t expect a compact car’s brakes to stop a loaded tour bus on a ten mile descent would we?  The simplest cure for brake fade is larger rotors.

        My disc brakes just don't feel right.  What's up?

This generic question usually takes many forms but they all usually point at the same problem - poor initial setup, bleeding or adjustment.  Incorrect setup can cause problems like squealing, mushy lever, unequal pad wear, lack of power and perhaps a few other things.  The most important step here is the most obvious - read the instructions!  This can't be stressed enough and it's the major cause of most brake related complaints.

All brake makers have their setup instructions plus much more information on their websites.  But sometimes it isn't your fault that the brakes are not set up correctly - the IS (International Standard) mounting tabs on the frame and fork can be miss-aligned even on NEW frames!  Then, no matter how meticulous you are, the setup will never be correct until the mounts are aligned (see below).

With one make of brake, the mechanism itself compensates for any mounting tab misalignment - and that's the Avid cable disc brake with its CPS (Caliper Positioning System) adjuster.  Of course rear Hayes mounts and front Post mounts don't have these problems either.  But with IS tabs any misalignment in the manufacturing process of frame and fork can cause problems.

But misaligned tabs can be re-aligned and there are, at the moment, two tools on the market for this - the Magura Gnann-o-Mat and the Hope Spot.  Both are tools for machining the mounting tabs into correct alignment.  Due to their expense they will probably be a shop tool and good bike shops should have them and charge a reasonable fee to align your tabs.

Frame makers should align their IS tabs during the building process just as they machine head tubes and bottom brackets.  It is unacceptable if they don't do this on a new frame and they should be taken to task over it.

How can I clean my brakes and bike?

It's ok to wash the bike and use soapy water.  Hose the bike gently, soap wash everything including the brakes and rinse.  The brake will squeal when wet.  For cleaning oily rotors use Isopropyl Alcohol or soapy water.

I just installed my disc brakes, but they’re lacking in power. Why?

Disc brake pads take a certain amount of time to “break in,” and to properly bed themselves in.  Until then you will not have full power and on some brakes in the early stages, you won't have much power at all!  See the owner's manual for bedding in tips from the various makers.  Just don't listen to the stories about pouring water or coke over the brakes to speed up the process.  20-100 stops should see the brakes at full power.  Just ride normally for two or three rides and apply the brakes many times especially on downhills.

        What can I do with warped rotors?

There are NO rotors that are dead flat and they can all be trued up - even most new ones. As rotors are a thin stamped steel product they all tend to be somewhat warped - some more or less than others. But warpage is curable so don't freak out. Warpage that causes brake drag or "zinnnggggg" needs to be fixed and luckily that's quite easy. I true up ALL my rotors and can usually do them in two minutes. They don't have to be dead-on but just fairly close. Grab a small clean adjustable wrench and a piece of something white. There are also special tools for the job on the market; the best ones come in a set of three.

Truing the rotors - Make sure you have lots of light so you can see well. Lay the piece of white paper or plastic below the bike on the floor. Now stand where you can look through the caliper and reposition the paper on the floor so the white background is visible through the caliper when viewed between rotor and pad. The light colored background lets you see what the rotor is doing inside the caliper when you spin the wheel.

When you're all set up, slowly spin the wheel and look for spots on the rotor which are out of true and touch a pad on one side or the other. When you find a spot which rubs or nearly rubs, rotate the rotor back out of the caliper 90 - 180 degrees, place the clean adjustable wrench on the rotor with the jaws just open wide enough to grasp the rotor, and verrrrry gently bend the rotor in the opposite direction.

A little movement goes a very long way here. Apply the brake lever after every pry to re-set any pad that has got squished back. Don't tweak hard or you will make things worse than they were. Don't forget - more is NOT better! Keep doing this until the rotor runs fairly straight and you can see and hear that it is not hitting the pads.

This is normally a quick job but I'll admit some have taken me a 1/2 hr or so to true. There are specific tools out there that make the job easy. One company markets a set of three tools - to be used together to isolate the warp. That same company even markets a trail tool that allows you to true warped and tweaked rotors trailside so that you don't get your sweaty, greasy fingers on the rotor. If you touch the rotor with fingers then clean it with isopropyl alcohol before you ride. Any oil or grease, yes even body oils, is not a good thing. The next best cleaning fluids are Windex or a light dish soap. Washing the rotors at bike wash time is not a problem.

There are good reasons for wanting true rotors. They are -
1. Prevent premature pad wear.
2. Prevent uneven, inconsistent rotor wear. Consistent rotor wear = consistent braking.
3. Eliminate pre-heating the calipers and fluid.
4. Eliminate the irritating noise factor.

Cable Operated Brake Questions     Back to Top»
 

Are cable disc brakes better than hydraulic? 

No.  Nor are they any worse.  A well-made cable brake will perform just as well, and in some cases, better, than some hydraulics.  Each system has its own benefits and merits.  A hydraulic system is better sealed, and requires no cable changes.  A cable brake is sealed just as well at the caliper, but will require periodic cable maintenance.   Cable brakes generally weigh more than hydraulics, but you generally get the trade-off with more adjustability.

Do I need to pre-stretch my cables?

No! In fact, doing so may damage the caliper, which is why it’s recommended against. Mechanical disc brakes derive a lot of their power from the leverage inherent in the caliper design, not from hand strength. As a result, the cables aren’t under as much stress as they would be using traditional rim brakes. It’s possible that some stretch will occur over time, but this can be compensated for using barrel adjusters or by re-clamping the cable at the caliper. Be sure if you do this to ensure that the cable is still too short to get caught in the rotor.

        Why would I want to run full-length housing or something like Flak Jacket or Full Metal Jackets?

Full-length housing means the housing runs continuously from the brake lever to the brake. There are a few reasons for doing this.
First, a full-length housing will protect the cable from the elements, keeping it free from dirt, rust, etc.  Second, full housings will keep friction down. This sounds a little weird at first, since intuition would say that more housing means the cable is rubbing more against it, meaning more friction. But in fact, a lot of friction is introduced at the cable stops. Plastic housing ferrules bend, tighter bends happen to fit the housing into the stops, and any break in the housing is a possible entry point for water, mud, grit, etc, that will all help to add friction. This is problematic for the rust problem, too, since water stays trapped in the housing longer than it would stay on the exposed cable, meaning more rust, AND rust that’s not obvious without removing the cable.

In extreme cases, and over a long period of time, the dirt and grit that gets in there will grind that rust away, allowing new rust to take place, as well as grind away at clean cable, contributing faster to cable failure… in all, a bad situation. Full-length housing helps to prevent this.

It used to be that another problem for this type of setup was compression of the housing, resulting in loss of braking power. But newer spiral-wound housings don’t compress anywhere near as much as older, cable-style twisted wire housings did, and many are reporting that the Kevlar housings put out by Jagwire and Avid are very good protection against compression.

Another reason some people are wary of running full housing, is that in order to use the cable stops to route the housing, they need to be drilled out, and some people are wary of permanently altering the frame. But there are some after-market hydraulic cable guides available that can be used instead. Zip ties can also be used, but not everyone wants or likes to do it that way. Some custom frame-makers offer housing guides in lieu of cable stops, eliminating this problem. In practice, it’s not too hard to use a Dremel tool to open up the stops. On steel frames, it’s a good idea to paint the now-exposed metal. On aluminum bikes, it’s not a concern.

Once you’ve decided to run full housing, it is a good idea to use Teflon or plastic lined housings, and even better to use Teflon coated cables in those housings, with a drop or two of Teflon based lubricant. Reducing friction is one of the main reasons for doing this operation, so using the Teflon coated cables can only help. Most cheap, house-brand housing is already plastic lined so fancy housing isn’t necessary.

Avid’s Full Metal Jacket is an alternate method for full length housing.  This uses stainless steel tubes for the straight sections of housing on the bike: the straight run down the fork, along the top-tube, and down the left seatstay. The idea is that straighter sections would cut down on friction normally encountered from bending associated with flexible housing. Whether this option really cuts down friction over a normal plastic-lined housing with Teflon coated cable isn’t clear. The cable stops still need to be drilled out for this system to be continuous or alternate means of attaching the housing must be used.
IRD’s Metawire is another alternative, using segmented aluminum housing instead of straight tubing, allowing more flexibility when routing the housing. In this case, the cable stops remain intact, and the Teflon liner-tube remains intact between stops.

Nokon’s Trac-Pearls and Konkavex systems are another interesting alternative, as both systems use alternating beads and small tubes with concave sockets at each end, so the housing system is an endless stream of ball-and-socket joints. Inside is a continuous PVC tube, meaning the system is completely sealed, and this system reportedly works very well around tight bends as well, such as that which would normally go from your brake lever to the front brake. The manufacturer also states that this system doesn’t weight more than traditional housing, so weight isn’t an issue, and the thin pvc tube seems to use normal cable-stops, so they won’t have to be drilled to run housing.

Flak Jacket housings are another Avid option using ferrules at the cable stops that allow the use of a plastic sheath over the cable, essentially protecting it from the elements in a similar fashion to the Metawire and Nokon systems, so it doesn’t require the drilling out of the cable stops to run the housing. The only difference is that the tube is not continuous with the liner of the housing; it simply slides over extensions from the housing ferrules that go through the cable stops. It’s probably a good idea to use a good amount of grease or something else to seal this joint.

         Hydraulic Brake Questions      Back to Top»

            Are hydraulic brakes better than cable? 

No, not as a generalized statement.  Nor are they worse.  Each system has its own merits.  A hydraulic system is better sealed, and requires no cable changes.  A cable brake will require some periodic cable maintenance.   Cable brakes generally weigh more than hydraulics, but you generally get the trade-off with more adjustability.

Hydraulic braking performance, regarding the transmission medium (oil in this case), will not deteriorate over the life of the brake.  Cables will be at their best on Day 1 and, depending on many factors, get worse over their lifespan.  This is all very subtle and hardly an issue.

What's the difference between Open and Closed hydraulic systems?

The difference here is simply that an open system has a brake fluid reservoir and a closed system doesn't.  The Hope C2 is the only closed system disc brake on the market.  All other disc brakes have open systems which means they have a reservoir for oil expansion (due to heat) and oil supply (for automatic pad pad wear adjustment).  The Hope C2 has a manual adjuster knob on the lever which adjusts a piston for fluid expansion and pad wear.

Why the different brake fluids? 

Brake makers decide what characteristics their brakes should have and specify the best fluid for the job.  There are two main types of fluid – mineral oil and glycol based which are commonly called DOT (3, 4 or 5.1) brake fluids.  The higher numbers are given to fluids with higher boiling points.  There is another fluid  –  a silicone based DOT 5 which is not used as a bicycle disc brake fluid.

You MUST, unless you’re willing to risk your brake’s seals, stay with the recommended fluids.  Read the manual!
Here's another major difference - DOT brake fluids dissolve paint and mineral oils don't.

Is bleeding messy? 

Only if done without care.  Just follow the makers’ instructions, think a little about the physics of fluid (think of the effects of gravity and siphoning) and proceed carefully and you won’t get oil all over the floor.  Just don’t do it over the living room carpet.  Here is a big tip - remove the pads before bleeding and don't handle them with oily fingers!  Oil is death to your pads.

I just got Hydraulic fluid/oil/chain lube on my new rotor/pads. Is there something I can do about this?

Any form of oil is death to your brake pads.  You shouldn't even get finger oils on the pads or rotor........!!!   It is recommended that before bleeding that the pads should be removed from the brakes so that they do not become contaminated.  Read your brakes' instruction manual to see what the makers say about this.  Isopropyl Alcohol is what all brake makers recommend for cleaning their rotors.

There are a few things you can try.....you can boil your pads in a pot of hot water, you can run them in the dishwasher, you can cook them in the oven, or you can cook them with a blow torch……none of which are condoned by any brake maker. Best option is to buy spare pads just to make sure you will have brakes in time of need.  For rotors you can try brake clean, rubbing alcohol works just fine and it is cheap, or dawn dish soap works good too (it will disperse the oil). 

Is there an easy way to route my hydraulic lines?

It depends on your bike.  As mentioned before, if you don’t have hose guides built into your frame drilling out the cable stops (or preferably using a Dremel)  is an option.  There are also hose guides that plug into your existing cable stops.  When all else fails, colorful zip ties always work.  Magura also has a "shrink-wrap kit".

Will air get in the lines if I turn my bike upside down?

Maybe, but only if your brakes were not bled and maintained correctly in the first place. For air to get into the lines (the only place where air can make the brakes feel mushy) it has to be present in the reservoir before the bike was inverted. Then what happens is that upon inversion the bubble enters the master cylinder piston area through the transfer port in the bottom of the reservoir. When you turn your bike the right way up and operate the brake you can now compress the bubble an hey presto - no brakes!

There must be NO air in the reservoir and the only effective way to achieve this is by pushing fluid through the system from its lower end while the reservoir cap is held on gently with a finger. This will displace some fluid and all the air. Simply filling the reservoir to overflowing is no guarantee that no bubbles will be left behind when the cap is replaced.

This is for brakes with reservoirs that can be opened by removing a cap. There are other brakes (Hayes and Formula spring to mind) where the reservoir is a flexible bladder within the lever body and this problem doesn't seem to be an issue.

Common Sense Tips!     Back to Top»

• Don’t touch the rotor! Be careful when the rotor’s hot when you finish riding unless you want to be branded.
• Don’t put fingers near the rotor when it’s spinning! You could chop off a finger.
• Have your levers loose on the handlebars! Then they swivel in a crash instead of snapping off. Read this one 3x.
• Don’t touch the rotor with bare fingers! Body oils can contaminate pads and reduce braking.
• Keep cable ends very short! Long ones can get into the rotor and lock the wheel.
• Have cables or hydraulic lines long enough for the bars to swivel all the way, each way, and enough for suspension movement!
• With self adjusting disc brakes don’t squeeze the levers with the wheel out!
• Don’t spray chain lube, WD-40, silicone or anything near a disc brake! Shield the rotor!
• Keep quick releases really tight!
• Run high spoke tensions.
• Stock some small parts for emergencies – pads, cables, fluid, bleed kit, olives, tubing, rotor bolts.

Glossary of Terms      Back to Top»

• Blade - the part of the brake lever that the fingers grip
• Bleed kit - the parts necessary for bleeding hydraulic brakes
• Caliper - the housing for the brake pads that applies the pressure to them. A slave cylinder
• CPS - Caliper Positioning System - Avid's system for caliper alignment
• Disc - rotor. The part bolted to the hub that the pads grab
• Disc hub - a hub with a mounting flange for a rotor.
• DOT - Department of Transport - a governing body that determines and regulates automotive standards
• Drag - force or noise from incorrectly set up brakes
• Fade - lowering of a brake's power due to overwork
• Hydraulic - operation by movement or force on a liquid
• IS - International Standard - a type of caliper mount with two tabs. Also a hub standard applied in the year 2000
• Master cylinder - the hydraulic piston assembly at the brake lever
• Mechanical - cable operated, in this context.
• Modulation - smoothness of linear operation. Lack of grabbiness.
• Mtbr.com - best place on the planet for bike and brake info.
• Mount - what a caliper is bolted to.
• Olive - a compression sleeve used to provide a seal on Magura hydraulic lines.
• Pad - a brake's frictional material which clamps the rotor or rim.
• Postmount - Manitou suspension fork caliper mounting system
• Pump - the action of the applied lever blade to move further from the handlebar due to fluid expansion because of heat.
• Reservoir - storage for extra hydraulic fluid on the master cylinder
• Rotor - disc.
• Self adjusting - brakes that adjust the pad to rotor gap automatically when operated.
• Slave cylinder - caliper.
• Tabs - caliper mounts; on frame and fork.
• Torx - a type of screw head similar to Phillips or Allen. Used on rotor bolts. Looks like a star.

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