Disc brakes on mountain bikes add expense. 18 years ago when I bought my first mountain bike one of the main purchasing considerations was how much it would cost. Without knowing it, I actually bought a pretty good bike for the time, a Gary Fisher Marlin. It was a hardtail with 26 inch wheels and rim brakes.
Then I rode that bike two seasons and saved a little bit of money for some upgrades. The first purchases were new hand grips and Juicy 7 hydraulic disc brakes.
Are Disc Brakes Better on a MTB than V Brakes?
I still remember shopping for those brakes wondering “is it worth it?”. And would they stop better? A test ride on an MTB from a local shop convinced me. Disc brakes on a MTB are way better! On a mountain bike, wider rims, exposure to water/mud and cable stretch detract from rim brake performance.
Can I Install Disc Brakes on ANY Mountain Bike?
NO -Unfortunately, some frames, forks and wheels inhibit disc brake installations. But, many bikes are capable of upgrading… below are the key things to look for.
-What Kind of MTB Frame is Needed for Disc Brakes
The frame must have attachment points for the disc brake system on the rear wheel. Two holes will be located on the side opposite the drive system (chain and gears). These attachments are called IS Mounts.
-What kind of MTB Forks Accept Disc Brakes
Most forks with a suspension will have the post mounts required for disc brakes. These will be threaded to accept the caliper attachment bolts.
-Are the Wheels Special for Disc Brakes?
The wheel hubs for both front and rear must be disc brake compatible. Two systems are used:
- Shimano Center Lock- which has a spline on the wheel hub that accepts a brake disc (OFTEN CALLED A ROTOR) and is locked in place with a lockring.
- 6-Bolt Hubs- which have 6 milled and threaded bolt holes to attach the brake rotor.
Different Types of Disc Brakes – How to Select
Disc brakes for bikes are sold in different sizes. The common measurements are:
- 140 mm
- 160 mm – recommended size for a beginner.
- 180 mm
- 203 mm
How much do Disc Brakes Cost for a Mountain Bike
I would budget about $100. This assumes you have the tools. You could probably install disc brakes with just a multi-tool as long as it contained a set of TORX and Allen head wrenches.
I’ve been really HAPPY for the last 1200 miles (and running) with my TEKTRO Auriga brand hydraulic disc brakes. (Links to Amazon for pricing and reviews)
To give you a price range, low end mechanical disc brakes will cost $48 for a complete set, while a highend Shimano XTR Brake groupset will cost $450.
Tools needed for Disc Brake Installation
I’m going to assume that the disc brake system you’ll purchased is pre-assembled and the brake lines are bled.
- Screw Drivers – attaching levers to handle bars
- Allen Driver Set – attach disc rotors and calipers – usually a 5mm.
- Torx Driver Set – attaching rotor disc bolts T25 is common.
- Torque Wrench – to correctly torque disc bolts and calipers.
- Clean rag and Isopropyl Alcohol – cleaning rotor.
- Side Cutters – trimming zip ties
- Thread Locker – for locking rotor bolts
- Ringlock socket – optional if installing Shimano Centerlock Rotors
A Bike Repair stand makes this job a SNAP. I highly recommend the Bike Hand Bike Repair Stand (Link to my review) This bike repair stand is portable, stable and a super value.
Steps for Installing Disc Brakes on a Mountain Bike
1. Remove the rim brakes (V-brakes) and handle bar levers.
2. Remove front wheel.
IMPORTANT: Whenever handling disc brakes try to keep the brake pads and rotor discs’ CLEAN. Gloves are suggested, wiping everything with isopropyl alcohol is a good practice.
3. The brake rotor will have a direction of rotation identification label on the rotor surface. Double check this is correct.
4. With a 6 bolt system snug down all bolts, then back off all 6 bolts – ¼ turn (loosen). The rotor should be loose to the wheel hub.
5. With the rotor loose twist it in a clockwise direction as much as the bolt holes will allow (it won’t turn much). This “clocking” reduces the chances that the bolts will be sheared off.
6. Holding the rotor in the clocked position, tighten the bolts snug by hand in a star pattern.
7. Align brake rotor to wheel hub and attach using 6 bolts or center lockring. For 6 bolt rotors, use thread locker if it isn’t already applied to bolt threads. The thread locking material is usually colored – blue. TORQUE TO CORRECT SPECS 4 to 6 Nm
8. Tighten bolts in a STAR pattern. This avoids bending and shifting the rotor on the attachment flange.
9. Wipe the rotor with a clean rag and alcohol or brake cleaner. Read this article HOW TO CLEAN DISC BRAKE – HERE for an in-depth article
10. Re-attach front wheel to fork.
11. Select front calipers, these will have shorter hydraulic brake lines.
12. Remove caliper spacers (usually red plastic piece between disc brake pads.)
NOTE: It’s a good practice to install the spacers whenever the rotor is removed from caliper. It’s very easy to over extend the brake calipers which makes it difficult to re-install the wheel/rotor.
13. Slide the calipers over the rotor disc and align the attachment points. Loosely attach the two bolts – snug but not tight. You want the caliper to be held but still moveable by hand.
14. Route the hydraulic brake lines up to the LEFT SIDE of the handle bars. The front brake always attaches to the LEFT SIDE.
15. With the line routed loosely attach the brake lever to the handle bars.
16. Lightly squeeze the brake lever and spin the wheel 2 to 4 times. This aligns the caliper to the disc brake.
17. Now it’s time to get the torque wrench out and set the torque on the wrench. Usually 5 mm Allen bit is needed and the typical torque is 75-85 in lbf or 8.5-9.5 Nm. TIGHTEN THE CALIPER BOLTS
18. Give the wheel a spin to insure it spins free. Even if it does rub, I’ve found coming back after test riding the bike and fine tuning is better.
After installing brakes, I like to ride the bike a half mile or so. The brake pads should be “bedded in” and any squeaks or rubs will normalize. In the past I’d spend a bunch of time adjusting the brakes during installation, only to find the squeaks re-occurring after riding.
19. Use zip-ties to hold the brake lines to the fork and frame as needed. Trim off zip-tie extra.
20. Position the brake lever to the angle that fits and tighten.
The front disc brakes are complete!
Before test riding, I always recommend doing a drop/bounce test. Basically, pick the bike up 4 to 6 inches and bounce it, listening for new rattles. Take the screw driver or Allen wrench that fits the brake lever and fine tune the placement of the brake levers.
Moving to the rear disc brakes is just about the same procedure.
1.Remove the rear wheel and attach the brake rotor as described on the front wheel.
Remember to torque the bolts down in a STAR pattern using a thread lock fluid. These are brakes you’re working on – think safety.
2. Loosely attach the caliper and route the brake line. A little bit of care is needed when routing the rear brake line up to the handle bars. Usually the line runs along the chainstay, up the seat tube and under the top tube to the handlebars.
3. Loosely attach the brake lever to RIGHT SIDE of handlebar.
4. Tighten caliper bolts using same procedure as front fork caliper.
5. Tighten brake lever to handlebar.
6. Zip-tie brake lines into position allowing for handlebar movement.
TEST RIDE and adjust levers as needed while riding in a safe area.
How to Adjust Hydraulic Disc Brakes on Your Mountain Bike
The first step is to diagnose the disc brake rub. Often removing the wheel and taking a little bit of time re-installing will fix a rub. Fast and easy – no tools required.
If the rotor rub is slight, put the bike in a bike stand and spin the wheel with a light behind the back pads. This is called “backlighting”. Usually you’ll see that the caliper is slightly off center.
Loosen the calipers bolts, and while holding the brake lever, re-torque the caliper bolts. Give the wheel a spin while backlighting.
If the rub continues, loosen a SINGLE caliper bolt and ever so slightly adjust the caliper position WHILE the wheel is spinning. When the rub disappears re-torque to the correct spec.
Benefits of Disc Brakes on a Mountain Bike
- Rim brakes get splashed with mud and water and lose most of their stopping power. This can be pretty scary flying downhill and not having the control you’d like. Disc brakes are up and away from the ground, the tire actually splashes the mud and water away from the center of the wheel.
- Additionally, if the rotor does get wet, the concentrated force applied by the calipers quickly wipes the rotor clean.
- Disc brakes offer more brake modulation with less lever force applied.
- Disc brakes aren’t affected by a bent rim or a wheel that is out of true.
- Disc brakes are self adjusting and don’t need adjustment until it’s time to replace the pads.
- A bent rotor is cheaper and faster to replace as compared to a wheel and rim.
Mountain bike disc brake MODULATION is the smooth progressive application of braking. This allows for easy hand pressure to control the braking intensity. Another way to say it would be a linear application of stopping power – no grabbing.
Recommended Brands of Disc Brakes
I think I counted 8 different brands of MTB Disc brakes. I’d stick with a brand that is easy to maintain and that has parts readily available. The three big brands are:
Shimano– which is my preferred brand. Like many bike components you can buy a compete brake set which includes everything to install disc brakes. Usually this is cheaper than trying to piece together all the parts.
Shimano sells a wide range of disc brakes.
The most basic cable/mechanical disc brakes are called Tourney and a full bike set will cost around $72 bucks. I wouldn’t recommend this though. You’ll spend hours adjusting the cable tension.
A good entry level hydraulic brake set from Shimano is called the DEORE M6000. At about $150, these aren’t the cheapest, but are far from the most expensive. As an example, a Shimano XTR Disc Brake Groupset will cost about $450.
TEKTRO– these guys were new to me until a couple years ago. These are the brakes came on my Specialized Camber have worked great. I highly recommend TEKTRO if you’re tight on a budget.
You can get a full groupset (includes both front and rear discs, calipers, levers and bolts) at Amazon. 160mm Tektro Hydraulic Brakes (LINK to AMAZON)
SRAM- I first started out with SRAM Avid Juicy brakes. I loved them and would say the brake modulation was probably a little better than the Shimano.
Unfortunately, I wasted a lot of time bleeding the SRAM brakes. I found out later that this was normal for SRAM and since I’ve switched to other brands I haven’t bled any MTB disc brakes. Just think how often do you bleed the brakes on your car? – NEVER
Stopping – the Final Word
If your bike is compatible, upgrading to hydraulic disc brakes is a super upgrade. For less than $100 buck you can get the Tektro groupset and have excellent stopping power and the satisfaction of doing a little wrenching on your MTB.