how to install and adjust disc brak

8/2/2019 How to Install and Adjust Disc Brak

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Page 1 of 15How To Install and Adjust Disc Brakes | Mountain Biking - Bike198.com

2/26/2010http://mountain.bike198.com/how-to-install-and-adjust-disc-brakes/


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How To Install and Adjust Disc Brakes

Bike Maintenance | 198 | March 11, 2009 at 7:14 am

Hydraulic disc brakes formountain bikes can be one of the most significant upgrades to your

current ride. Hydraulic disc brakes provide superior modulation, power and control over theirmechanical counterparts (both mechanical disc and cable driven v-brakes). With hydraulic brakingsystems for mountain bikes, you can stop easier and control your speed with ease as themodulation allows the rider to control their bike in technical and fast riding situations.

You have your new set of hydraulic disc brakes ready to go on your mountain bikewhere do westart?

What is required to install disc brakes?

Before you jump at the chance to upgrade your current mountain bike to hydraulic disc brakes,

you need to make sure that your bike has the necessary mounts for installation. These are themounts you are looking for

The Fork

On your suspension fork, you are looking for IS or post mounts for disc brakes. If your bike haspost mounts, you most likely already have disc brakes installed. Most 2009 forks (if not all) nowcome standard with post mounts. If you are in the process of upgrading, you are most likelylooking at IS mounts on your suspension fork.

Images: Post mount on left; IS mount on right

The Frame

On the rear of your mountain bike frame, you need to make sure that you have those exact same ISmounts on the rear triangle on the non-drive side of your frame. You are going to mount thecaliper to these mounts during installation.




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The Hubs

To be disc brake compatible, your mountain bike hubs need to have mounts for the disc brakerotors. These mounts are going to come in one of two different configurations. The most commonof these is a 6 bolt mount on the hub body that looks like the picture below. Shimano also makestheir own proprietary Centerlock system which will be found on some of their hub sets.

Images: 6 Bolt on left; Centerlock on right

Your mountain bike doesnt have these mounts?

If your mountain bike has the required mounts, but your hubs do nota new set of wheels aregoing to be required. If your frame or fork does not have the IS or post mounts for disc brakes,you will not be able to install the brakes on your bike.

Installing Disc Brakes for Mountain Bikes

For the purposes of this article, we are going to assume that your hydraulic lines are the correctlength for your frame. In many cases, the stock length will work perfect and trimming the

hydraulic lines may not be needed. If you lines are too long for your mountain bike frame, youshould have them fitted to your bike.

Before we start

Before you start the installation process, make sure that all of your parts match. Your mountingbrackets should match up with your rotor size. Typically, rotors come in these sizes140mm,160mm, 180mm, 183mm, 185mm, 203mm. The caliper mounting bracket determines how highthe caliper sits off the frame to contact the correct rotor size.

Tools Required

T25 Torx Wrench for the caliper bolts4 or 5 mm Hex Wrench




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Torque Wrench Preferred

Step 1 Mount the Rotors to the Hubs

To get started with the process of installing your new hydraulic disc brakes on yourmountainbike, we need to install the rotors on your hubs. Install the disc brake rotors on your mountain

bike hubs using the T25 Torx wrench. Typical mounting requires 40-60 ft lbs. of torque. Becareful with the torx bolts because they strip very easily. Every bolt should have blue lock-titealready applied to prevent vibration loosening. Once this is complete, install the wheels back intothe dropouts with the brake rotors mounted.

Step 2 Mount the Rear Lever to the Bars and Feed Line

The first step in this process is to mount the rear lever to your bars and feed the line to the reartriangle of your frame. Once you have properly fed the hydraulic line through the correct mountson the frame, bolt the caliper mounting bracket to the frame, tighten the bolts and loosely attachthe caliper to the mounting bracket. Do not tighten down the caliper bolts at this time.

Step 3 Mount the Front Lever and Feed Line Through Fork

Now, mount the front brake lever and feed the line through the inside ofthe suspension fork. At this point, you can feed the line to the inside or outside depending on your

preference. As you can see by the picture, I like to keep the line out of the way and out of sight.Make sure that the hydraulic line for the front brake is still well organized with the rest of yourshifting cables and rear brake line.

Mount the correct caliper mounting bracket, tighten those bolts (typically around 80 ft. lbs. forpost mounts and 110 ft. lbs. for IS mounts) and loosely attach caliper to the mounting brakets

leaving the top two bolts un-tightened at this time.

Step 4 Secure Hydraulic Lines

Disc brake ready frames have mounts down the frame tubes that will secure the hydraulic lines.Use small zip ties and cut the excess as you go. On the suspension fork, secure the brake lineusing a supplied mount or by using a medium zip tie around the arch of the fork. Make sure thatthe line is completely out of the way of the spokes as the wheel turns.

At this stage in installation, turn the bars from the extreme left to the extreme right and make surethat all of the lines and shifter cables interact correctly with each other. If there are any conflicts

now is the time to make adjustments.




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Lets Get to Adjusting Your Disc Brakes!

Now that the brakes are on the frame and secureit is time to get these massive stoppers adjustedand ready for trail action. When you have properly adjusted hydraulic brakes, all is great in themountain biking world. Improper adjusting can mean brake drag and noise, and both of theseequal unhappy riders.

Adjusting the Brake Levers

The first step in adjusting brake levers is making sure the lever is positioned horizontally on thebars to fit your hands. I, like a lot of riders, prefer one finger braking with quality hydraulicbrakes. I make sure the levers are inboard enough to make this comfortable for all day riding.Experiment some and find your comfortable spot.

For lever height, I wait until I have properly adjusted the brake calipers.

Adjusting the Brake Calipers

Note: The following tips for adjusting mountain bike disc brake calipers apply to post mount stylecalipers like the ones pictured. Some older disc brakes are IS calipers that require shimming toget correct alignment with the disc brake rotor.

Remember when we left the calipers loose on the mountingbrackets in the above steps? This is whywe need to adjust the lateral positioning of the brakecalipers so they do not come in contact with the brake rotors during free spinning. When you havedrag, you have to exert extra energy to move the wheels. When the calipers are not straight withthe rotor, this can result in brake howl and other annoying noises on the trail.

I have found the following directions this easiest when adjusting mountain bike brake calipers:

Spin the wheel using your hand or cranks.Slowly compress the brake lever and hold.

Tighten caliper bolts to 60 ft. lbs.Release lever.Spin wheel to check for drag.




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Video of the action

It doesnt get much easier than that. With some brakes, this doesnt work right away. If you arehaving a hard time getting out all of the drag in your hydraulic brakes, try this method.

Slowly spin wheel.1.While wheel is spinning, position caliper by hand into position where there is zero drag.2.Keeping the wheel spinning, tighten caliper bolts.3.

Adjusting Vertical Position of Brake Levers

ow that everything is set and ready to go, lets get those brake levers exactly where we wantthem. Tighten the brake lever bolts to the point that they do not slip, but you can still move them

by hand. Ride your bike around a flat area with the saddle height at your usual ride setting.Position the brake levers to that your hands comfortably rest on the levers. Once you find yoursweet spot, slightly tighten the levers into place. Ideally, you want the levers to move under hardhits but not during riding to help prevent damage during wrecks.

Everything Is One and Adjusted Now What?

Ready for the trail?! Not quite yet. You need to get out and bed-in/break-in yourpads and rotors.The easiest and fastest way to accomplish this is by finding a straight road that declines with as

little traffic as possible. When you are at the top, pedal up to speed and gradually apply the brakes.Do not apply the brakes to the point that they lock up. The idea is to brake evenly and consistentlyacross the rotor surface. Repeat this process several times until you really feel the brakes start to

bite.

After this process is complete, recheck caliper positioning and hit the trail!

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17 Comments

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March 11, 2009 at 11:45 am

just remember not to strip the fork when installing said brakes.

Reply

jason griese says:March 11, 2009 at 11:49 am

Thanks man I just got newpads for my XT brakes and was sketchy on the process.Really Thanks .

I have a question about mineral oil which is used in my XT brakes , Is this the same mineraloil that would be sold in a hardware store?

Let me know. Can I link your post to my Site?

Jason

Reply

2.

Tweety says:March 11, 2009 at 11:58 am

Jason,No, you cant use mineral oil from a hardware store or drug store, as theyre typicallydifferent viscosities and have different boiling points.

See http://www.cyclingcentralva.org/geninfo.html

Furthermore, I personally tend to not mix mineral oils across brake manufacuturers, thoughsome do. Stick with the shimano brake fluid / mineral oil for your brakes, and youre all butguaranteed to have years of problem free use (speaking from personal experience)

Reply

3.

jason griese says:March 11, 2009 at 12:27 pm

Thanks I didnt even think about the viscosity with the bike brakes. The Truck sure theTriumph definitely . Thanks a lot.

Reply

4.

198 says:March 11, 2009 at 2:36 pm

@jason griese

Tweety is right. While I think it would probably be ok to use Shimano vs. Magura(the other brand that is mineral oil based)I wouldnt. Stick with the brand specificto insure that the oil interacts with the rubber seals correctly.




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I have some background in testing DOT brake fluids with rubber seals and it isamazing what a different spec will actually do to rubberit expands, contracts,deterioratesyou name it!

Link away!!! As long as you arent copying the entire articlelink what ever youwant tothanks for the support!

Reply

Jason Hsays:March 11, 2009 at 1:58 pm

I just completed the above steps to upgrade my bike from some entry level mechanical discbrakes to Avid Juicy 5s.

Currently, the levers are almost bottomed out against the grips when fully engauged. Is therea way to adjust the brake engaugement position and level position without adding hydraulicfluid?

Reply

5.

198 says:March 11, 2009 at 2:38 pm

@Jason H

The Juicy 5s have no bite control so you are going to have to re-bleed your brakes. Itsounds like you have a good bit of air in the lines, so this would be the smart route togo anyway. The Juicy bleed process is pretty straight forward, but you will need touse the Juicy bleed kit.

Reply

Graham says:April 21, 2009 at 7:30 am

Good article but youve written ft.lb where you shouldve put in.lb. Probably should changeit as Im sure someone will try it with a really big torque wrench.

Reply

6.

Socratic Bob says:June 3, 2009 at 6:00 pm

Im puzzled as to when the hydraulic fluid is added. I never saw it mentioned once in thearticle. Hard to break em in with no fluid, right?

Reply

7.

198 says:June 3, 2009 at 6:29 pm

Bob,




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Every single set of brakes I have ever had came fully bled ready to install on the bike.No need to add fluid.

In the rare cases that I have to cut the lines to fit the bike (which I only do if they areextremely long as you can affect resale value), a simple bleed procedure is all that isneeded.

Reply

Socratic Bob says:June 5, 2009 at 11:56 am

Thanks. Obviously Ive never installed a set. My current set (bought on thebike) have been acting up and looking to do some maintenance. Front leveralmost bottoms out under hard braking. Ill find an article on bleeding.

Thinks for filling in the grey area.

Reply

jon says:June 8, 2009 at 9:46 pm

hey guys, just got back on my bike after a years because of meitanence issues and me beingtoo lazy to fiz them. i just installed disc breaks and accidentely, while the wheel was out, i

pressed on the front break lever and closed up the space where you would put the wheelback in, now its rubbing and the wheel doesnt spin that fast, if it spins at all. anyone knowwhat could be wrong and how to fix it, any siggestions would be appreciated

Reply

8.

198 says:June 8, 2009 at 9:50 pm

Jonyou just need to push thepads backyour pistons have moved too far out.Using the spacers provided with your brakes is the preferred way, but you can alsouse a tire lever or flat blade screwdriver. If you end up using a flat head screw driver,make sure that you do not damage thepads while spreading them apart.

Other than thatyou should be good to go!

Reply

Socratic Bob says:June 12, 2009 at 11:54 am

I finally got around to bleeding the Hayes So1e. It didnt go so well. Bled them per themanufacturers instructions 3 times, and the levers still hit the handlebars. There were noobvious errors and everything happened the way the Hayes manual described.

Its interesting that I can find countless accounts of the same thing happening to others, butno explanations beyond the manufacturers instructions. For me, the brakes never pump upat the end. If fluid has been lost out of the system, does it take a lot more pumping of the

9.




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levers? A mechanic in the bike shop said that it should only take a few pumps. Maybe hedoesnt usually bleed bikes that lost most of their braking pressure. Any thoughts?

Reply

198 says:

June 12, 2009 at 1:07 pm

Have you checked all of the fittings to make sure there are no leaks or a leak in thecaliper. Typically, when there is air in the lines (unless it is A LOT!)you are able toget the brake lever to stiffen up after pumping it several timeseven if it is just alittle bit.

Reply

Dbag says:June 13, 2009 at 3:23 am

thank you 198. your a stand up guy.

Reply

10.

gregory meno says:August 27, 2009 at 10:22 am

I read your howto on disc brake setup. I see someone else has posted this reply but it is aserious oversight. Please change:

Tighten caliper bolts to 60 ft. lbs.

to in. lbs. srsly people are going to be breaking bolts and stripping frames

Or you could leave it more generic:refer to manufacturer instructions for tightening torque.

Reply

11.

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Tags: adjusting disc brakes for mountain bikes, how to adjust mountain bike brakes, how to install disc brakes, how toinstall mountain bike disc brakes, hydraulic disc brakes for mountain bikes

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