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Disc brakes are taking over the cycling world. It is becoming more difficult to find a new bike without them and that’s for some good reasons. Disc brakes are more powerful, more consistent and more durable than a standard brake. With any new product there are new things you need to learn and here are a few tips we would like to share.
The wheel with disc brakes is the same as with rim brake
Just because your new bike has disc brakes, doesn’t mean that everything is new. In fact, the skills you learned to take the wheel off your old bike with rim (pad) brakes are still completely relevant. Specifically, if you know how to operate a quick release, you can take the wheel off a bike with disc brakes. Consequently, with a disc, there is actually less to worry about than with a standard rim brake. However, if you don’t know how a quick release or thru axle works, read below.
How does a Quick Release work
A quick release allows you to remove your wheel without tools. Moreover, the quick release is installed through the center of your wheel allowing you to clamp the wheel into the bike. Basically, a quick release is a very long bolt with a cam lever on the end. It’s the cam lever that gives the quick release its powerful clamping force. To remove your wheel, simply flip the lever open, and remove the wheel. If it’s a front wheel, you will also need to unthread the quick release nut on the opposite side from the lever.
Flipping the lever open widens the quick release. This action is what gives a quick release it’s clamping force.
Quick release levers are marked “open” and “closed” on the lever. Be sure to always close the lever when tightening the quick release lever in place. If the wheel is tight, and you can read “open” the quick release lever is not installed properly.
How does a Thru Axle work
Thru axles work similarly to quick release levers. The main difference is that a thru axle needs to be threaded out of the frame and removed completely for the wheel to come out. Consult your bike manufactures manual for the details on how to remove your thru axle.
Thru Axles slide through both frame and wheel and thread into place.
So what is difference between mechanical or hydraulic disc brakes?
When it comes to removing a wheel, the main difference is knowing if your disc brakes on your new bike are mechanical or hydraulic disc brakes. The differences come with the way that lever force is transferred to the caliper or pad around the brake disc rotor. At one end there is a cable that operates the brake system, sometimes referred to as mechanical disc brakes. In contrast hydraulic disc brakes use a sealed, fluid filled system as the means apply pressure. In the case of the mechanical disc brake you don’t need to worry about anything. You can open the quick release and remove the wheel with no other issues. For hydraulic disc brakes, you only need to take care not to squeeze the brake lever if the wheel is not in place in the bikes caliper.
You shouldn’t squeeze the lever without a disc rotor in place. This is because of hydraulic disc’s auto adjusting pad (caliper) wear valve. If you make the mistake of squeezing the lever without a disc rotor in place. The valve adjusts as if you just wore through 3mm of pad material (the thickness of a rotor). If this happens, don’t worry, just get a flat piece of clean, oil free, metal to pry the pads back apart again. Even if you spread those pads too far out, once the rotor is back in, a few squeezes of the lever will get the brake adjusted properly again.
Putting the Wheel back In
When replacing the wheel on a disc bike, there is one new detail to take into consideration. Generally speaking, the wheel fits into the bike normally. Just verify that the rotor is inserted into the caliper (pad) properly. For instance, if the rotor isn’t centered into the caliper, it will rub. Therefore, verify that the wheel is centered in the bike straight.
Disc brakes were introduced on bikes as early as the 1950’s with Shimano making an actual hydraulic disc in the mid 1970’s. There were versions of the Schwinn Stingray series (released in 1971) that came stock with a rear disc brake. Let’s fast forward more than 25 years to the first market acceptable disc brake -The Hayes Mag disc. From its release in 1997, disc brakes have found their way onto most mountain bike, hybrids and now road bikes. With 20 years in development, disc brakes are more powerful and more serviceable than ever before. Read on to learn the basics on how your disc brakes work and how to keep them working well.
Original Schwinn disc and 1997 Mag brake, both made by Hayes
How Hydraulic Disc Brakes Work
At their most basic, the brake lever moves fluid through a system and that fluid flows to the pads that press on the rotor. There are more details that make one brake work better than another. However, at the root, all disc brakes are very simple. The reasons the system is so simple and works so well is based on the following. Both the pad and rotor materials produce excellent friction. Additionally, the natural properties of fluids help transfer lever force without compression and absorb excess heat.
How Mechanical Disc Brakes Work
Mechanical disc brakes share the same pad materials and rotors as hydraulic systems; Therefore, they have very similar stopping power. Where mechanical system differ is they use a standard brake cable to actuate the brake instead of hydraulic fluid. Mechanical discs have a small lever on the brake caliper that is pulled by the brake cable, moving the brake pads and stopping the bike. The benefits to mechanical disc brakes is a larger lever shape choice, lower cost, and easier adjustment. On the other hand, because mechanical systems don’t use fluid, they are not as powerful and don’t manage heat as well as hydraulic systems. For that reason, on longer descents, mechanical brakes can under perform compared to their hydraulic counterparts.
Why disc brakes are more efficient
Unlike rim brakes, disc brakes don’t rely on a wheel being straight and round. Even if you were to accidentally dent of bend your rim, with a disc, you can still brake confidently. Another reason disc brakes are more efficient is that they produce a massive amount of friction. That friction, in concert with the venting on the disc rotors clears debris off the rotor and allows the brakes to work through all conditions. Ultimately, disc brakes are more efficient because they require less maintenance. In fact, hydraulic disc brakes self-adjust for pad wear they don’t require you to adjust them.
Why adjust the disc brakes caliper
Adjusting the brakes caliper is necessary if you hear the brake rubbing, or if they aren’t helping you stop well. Before adjusting a hydraulic brake, squeeze the lever to determine if you system needs to bled. If the lever feels spongy when you squeeze it, you need to bleed the system. It’s best to take it to your local shop and have the pros handle it. However, If the lever moves freely through its range, then has a firm feel once the pads hit the rotor, you can proceed without bleeding the system.
How to adjust the caliper to eliminate noise on hydraulic brakes
To adjust the caliper, loosen the two fixing bolts on top of the caliper (they may be under the chainstay on road bikes or in front of the rear quick release). Then snug both bolts up until the caliper stays in place, but is still move able with some effort on your part. WARNING! The rotor can be sharp and cause serious injury to your fingers. While spinning the wheel, keep your fingers clear of any spinning part.
While looking into the caliper, try to position it so there is equal space between each pad and the rotor. Once the caliper is centered spin the wheel slowly – in a perfect world there is no noise. If you are hearing the rotor rub on the pads, readjust until you get no noise. In some cases, you may need to straighten the rotor, this is a job best left to a bike shop professional. Once you are happy with the calipers position, tighten down the fixing bolts and you are done!
Here you can see equal between the rotor and pads on both sides.
Adjusting mechanical brake performance
If your mechanical disc brakes have recently lost power, or the levers pull too close to the bar, you can easily adjust them for better performance. Before you adjust the brake, inspect the rotor and pads for any contaminants. Usually, contaminants come int he form of chain lube splattered from an over lubricated chain. If you see any oily residue on the rotor, the rotor needs to be cleaned, the pads will also need to be cleaned or replaced before you can proceed (denatured alcohol works well).
Most mechanical disc brakes have a fixed pad, and a moving pad. The moving pad pushes the rotor into the fixed pad, and creates stopping power. Because these brakes operate differently than a hydraulic system, they need to be adjusted differently. First, you want to align the caliper so the rotor is as close as possible to the moving pad without touching. Next, thread the fixed pad in until it is as close to the rotor, but not touching. With both pads in place, loosen the cable pinch bolt on the side of the mechanical brake, pull the cable tight, then snug the pinch bolt again. Continue to adjust until you get the performance and lever feel you prefer.
The Lever (green) is pulled, pushing the moving pad (also green) into the rotor (red). The Rotor is then flexed into the fixed pad (blue).
Trouble shooting disc brakes
Hydraulic brakes have a mechanism built into the master cylinder that auto adjusts for pad wear. It’s a great little valve that eliminates the need to re-bleed the brake continually as the pad wears. This valve can also lead to problems if you squeeze the brake lever without the wheel in your bike. The brake will adjust as if you just wore through 3mm of pad material (the thickness of the rotor) and not leave enough room between the pads to fit the rotor back in. To solve this issue you can either take the bike into a local shop or find a wide, flat, clean, metal tool to fit within the pads, and pry them apart again.
In cold temperatures
In temperatures below freezing, hydraulic discs that use mineral oil as a fluid can behave differently. As the mercury drops, the mineral oil can thicken and make the lever feel sluggish. You will find that once the temps rise, the brake will feel normal again.
Overall, disc brakes are the next step in brake evolution. They are more consistent, more powerful and easier to actuate than any other type of brake on the market. With every new evolutionary step, there will be some hesitation to try “the new”. Even though there may be some hesitation, you should not fear buying a bike with disc brakes. Thanks to years of iteration and market demand we now have disc brakes that are inexpensive and functional.
In the late 1920’s, in France, there was a bike race under way and it wasn’t the Tour De France. Instead, this race was a technological race that brought the derailleur into the light. Before 1928, bicycles had a maximum of two speeds, and you needed to remove the rear wheel to change those gears. As there was need for quicker shifting, the bicycle derailleur was born. Initial derailleurs consisted of nothing more than paddles that were actuated by steel rods located between the rider’s legs. Needless to say, there was a lot of finesse that went into shifting those bikes. Then after the second world war parallelogram derailleurs, what we use today, were developed so riders could shift their gears with ease. Read on to see how to get the most out of 100 years of technological advancements. You will find adjusting your front derailleur is easy if you follow these steps.
Early “Rod Style” Benelux front derailleur – Yikes
Front Derailleur parts
Limit screws (A) – The front derailleur needs to work within the largest and smallest ring. Limit screws work to stop the front derailleur from shifting outside of its intended range. They are adjustable as to match different types of cranks.
Derailleur Cage – The cage is what holds the chain on gear and what presses on the chain to move it from one gear to the next. The outer portion of the cage (C) is what helps the chain move from larger gears to smaller ones. In contrast, the inner portion of the cage (B) forces the chain from smaller gears to larger ones.
Common parallelogram front derailleur found on Hybrid and Mountainbikes
Derailleur Fixing Bolt (D) – The bolt that holds the derailleur in place on the frame. By loosening this bolt, you can re-position the derailleur for angle and height.
Cable Pinch Bolt (E) – The Cable that controls shifting needs to be held firmly in place. The pinch bolt does that job.
Different Pinch bolt and fixing bolt position for MTB/Hybrid (above) and Road (below) derailleurs
Location, location, location
You guessed it, the most important part of adjusting the front derailleur is its location. If the derailleur is not positioned properly, you will never achieve proper, noise free, shifting in all gears. The reason location is so important is that the front derailleur cage is formed to position the chain in very specific locations.
First step in adjusting the front derailleurs location is to set its height. You need enough room to fit a Nickel between the teeth on the largest chainring and the bottom of the outer cage when they are lined up. Any more clearance than that and the derailleur tends to have issues pulling the chain down from larger gears.
you should be able to fit a Nickle between the derailleur cage and chainring
Once you have the height set, adjust the angle of the front derailleur so that the outer cage and chainrings are parallel. Any misalignment will result in poor shifting and excess noise.
Proper alignment on the left, and misalignment on the right
Set the lower limit by adjusting the screw marked “L”. To do this, shift the rear derailleur all the way up into the largest cog. Next check to see if there is clearance between the chain and the front derailleurs inner cage with the chain on the smallest chainring. If the chain is running on the inner cage, thread the limit screw out until you have 2-3mm (that nickel distance again!) between the chain and inner cage. When the opposite is true and you have too much clearance between the inner cage and chain, thread the limit screw in until there is 2-3mm of clearance.
Your Front derailleur should be properly aligned and the lower limit should be set at this point. The next step is to attach the cable to the Pinch bolt. Attach that cable by first making sure your shifter is in its lowest gear, Then pull the cable tight, and finally tighten the pinch bolt onto your cable. Usually, you can shift smoothly up from the smallest ring into the next gear right away, but if there is hesitation going up add cable tension either through a barrel adjuster or by loosening the pinch bolt, pulling the cable tighter, and tightening the pinch bolt down again. If the chain wants to shift up from the small ring over the next ring, release some tension. You know you have it right when the chain can pass from one gear to another smoothly and confidently without any banging or skipping noises.
Setting the upper limit is as easy as getting the chain onto the largest chainring and threading the limit screw to offer 2-3mm of clearance between the chain and the outer cage. While shifting, ensure the chain cannot be shifted over the large ring and off the crank.
This guide is great if all the parts are new, but won’t overcome many issues related to worn or dirty parts. The most common shifting issue with older gears is poor upshifting. Chainrings are built with ramps on the inner surface to easily guide the chain from smaller to larger rings. As chainrings wear, these ramps wear as well. If you are having serious issues going from smaller to larger gears, but the gears are silent and problem free otherwise, you may want to consider replacing the chain, chainrings, and gears in the rear.
These Praxis Works chain rings have some of the best shifting thanks to carefully placed ramps.
Another key wear item is the front derailleur itself. Derailleurs are designed to pivot off a parallelogram design that requires each pivot run smooth and precisely. As the Front Derailleur wears, these pivots can begin to bind, while they generate play, leading to poor shifting.
Finally, dirty or corroded cables are a key cause in poor shifting. Replace cables once a year and lube them intermittently to keep them running smooth and freely.
When is enough, enough
Working on your bike is fun, but can be frustrating if things aren’t going according to plan. When things get out of hand, don’t be afraid to start from scratch and go back to step one. Any missed initial steps will make further steps impossible to complete. Also, remember that if it gets too tough, your local bike shop is happy to walk you through the process. You will pay a fee, but the one on one instruction is well worth it.
It goes by many names, the rear derailleur. It is also known as the “s,” the “hangdown,” or the mech. Here in the U.S. we refer to it as the rear derailleur. The device that moves your bike’s chain from gear to gear letting you traverse hills with ease. Even though derailleurs are sturdy and relatively maintenance free, they do require attention occasionally. Look below for the step by step instructions on how to adjust your bike’s rear derailleur.
Rear Derailleur Terminology
Twist shifter – A shifting device that rotates around the handlebar like the throttle of a motorcycle.
Trigger shifter – A Shifter that activates by pushing or pulling a set of paddles with your thumb and index finger.
STI shifters – Technical this stands for Shimano Total Integration and speaks directly about one brands type of road bike shifter, but it has become the generic term for any drop bar shifter/brake lever combo.
Thumb shifter – A shifter that can be mounted in many places like; the stem, bar end, brake lever, or top of the bar. These shifters are the most rudimentary type of shifter, and operate by simply actuating a lever with your thumb.
(A) Jockey Wheels- two small wheels on the derailleur on which the chain run. They are mounted onto the derailleur cage
Limit screws- The limit screws control the area of motion a derailleur has. On most derailleurs there are three limit screws: the upper limit, Lower limit, and B-limit. The upper limit screw sets the maximum distance the derailleur can shift in high gears. The lower limit screw sets the maximum distance the derailleur can shift in the lower gears. The B-limit screw sets the distance the upper jockey wheel sits from the cogs.
(B) Barrell adjuster – This is an adjustment device on the back of most derailleurs. It is the area where the derailleur cable enters the derailleur and can increase or decrease the cable tension by threading it in and out.
(C) Pinch bolt – The pinch bolt is where the derailleur cable gest secured.
(F) Derailleur hanger – The portion of the bike frame where the rear derailleur is mounted.
Not defined above is the Upper Knuckle (E), and lower knuckle (D)
Is everything straight?
The cogs your rear derailleur shifts across can have as little as 2.14 millemeters of spacing between them. Considering the spacing is so narrow, look to see that everything is aligned properly before you start adjusting your rear derailleur in vain. Look first at the derailleur itself from behind. You should be able to see if the derailleur itself is aligned properly. A tell-tale sign of damage is when the two Jockey wheels don’t line up with the cogs or each other (see picture).
Next assure that the derailleur hanger is aligned properly. This is easily seen when the derailleur appears straight, but not in line with the cogs. Consequently, if either the derailleur or derailleur hanger are bent, it’s best to take it into your local shop for a remedy.
Step 2, A man has got to know his limitations
Before attempting to adjust the derailleur properly, set its usable range. First, loosen the pinch bolt and let the derailleur run on the smallest cog. Next, pedal forward while visually and audibly inspecting how the chain runs on the smallest cog. The chain should run smoothly without any clicking, or skipping noises. If it runs smoothly, don’t worry about the upper limit. when you do experience skipping or noise, look closely at how the chain runs on the cog (looking from behind is easiest). If the chain isn’t coming directly off the upper jockey wheel and going straight onto the small cog you need to adjust the upper limit. By threading the limit in or out you can adjust where the derailleur sits in relation to that smallest cog (note: the limit screws don’t need to get “tightened” down, they simply act as a stop for the derailleur).
Once the upper limit is set, pedal forward and push on the derailleur lower knuckle until it moves the chain into the largest cog. If the chain has issue getting into the largest cog, or jumps over that cog into the wheel spokes, you need to adjust the lower limit screw in a similar fashion to the upper limit screw.
Rear Derailleur Tension
With the limits set, you can now move on to tightening the cable and trying to shift. Make sure the shifter is in its lowest gear by shifting down while gently pulling on the shift cable. With the shifter in its lowest position, ensure all housing ends are settled into the frame properly then pull the cable taught through the derailleur. With the cable taught, tighten the derailleur pinch bolt onto the cable. Trim any excess cable so that only about one inch of cable extends beyond the pinch bolt and crimp it off as not to fray.
While pedaling, shift one gear up. Ideally, the chain will easily move from the smallest cog up to the next cog. It should stay on the second cog and run quietly and smoothly. If it hesitates to get to the second cog, increase cable tension by rotating the barrel adjuster out. If you cannot increase tension enough with 3 or 4 turns of the barrel adjuster, thread it back in, loosen the cable pinch bolt, pull the cable taught, and tighten the pinch bolt again. Once you have the chain shifting up the cogs easily, check to see if it will smoothly move back down the cog stack by shifting from the largest cog down and inspecting. The only difference is in the adjustment. If the chain hesitates to move down the gears, turn the barrel adjuster in (relieving cable tension).
Rear Derailleur Trouble shooting
What happens if you can get the chain to move up the cogset well, but can’t get it to move back down the cogset easily. In some cases, the cable and housing can be corroded and causing drag. This drag won’t affect the shifting moving up the gear set, but it will stop the derailleur from returning. In tis case, you can clean and lube the cables and housing, or just replace the cable and housing all together.
Additionally, there may be a grinding/banging noise in only the largest cog. That noise is caused by the upper jockey wheel running on the largest cog. To remedy this, tighten the b-limit screw until the noise subsides.
Finally, a common problem is if you get skipping while pedaling up steep grades or under load. If your derailleur is adjusted properly, and you’re getting skipping, it may be related to a worn out drivetrain. As your chain ages, it stretches slightly. As the chain stretches, the front face of the gears will wear in unison with the chain stretching. Once the chain stretches beyond the point where it will mesh with the gears, you will experience skipping under load.
Working on your own bike is fun. Also, your appreciation for the technology and engineering that goes into what is considered a simple machine will grow with each turn of the wrench. Periodically, you will run into a problem you cannot solve. If that is the case, bring your bike to your local shop, talk honestly with the mechanic about what you tried and what you are trying to accomplish. As a result, you will find that most mechanics will be happy to teach you what you need to know.
Shift gears to the terrain you are riding can take you miles from home with ease. Over hills and through tough valleys, all thanks to the ability to know how to shift your gears. Learn the what, how, when and why of shifting your bike below.
Shift Gears and Its Terminology
Before we jump into how to shift your bike most efficiently, lets cover the basic parts. Beyond the chain, there are many moving parts that make up the drivetrain on your bike, allowing you to shift gears.
-Cassette and freewheel
The gears attached to your rear wheel are called the cassette or freewheel. While they are mechanically different, for the act of shifting, they operate identically. These gears are built with teeth that sit higher, lower, or at an angle depending on where they are located. The different tooth profiles allow the chain to seamlessly shift from one gear to the next. These gears come in groups of 5 up to 12 depending on the shifting system you have. Overall, the smallest and largest gears are close in size regardless of the amount of gears.
The chainrings are the gears attached at the middle of the bike where your pedals are. Most bikes have between 1 and 3 chainrings. You will notice that the teeth on the chainrings have similar profiles to those on the cassette. So if you see a tooth that is smaller or oddly shaped, don’t immediately assume it’s damaged. Basic chainrings will be stamped out of steel while more expensive ones are machined out of aluminum. The machining makes these aluminum rings both lighter and shift better.
The derailleurs are the mechanisms that physically guide the chain from one gear to another. Most bikes will have two, a front and a rear. The front derailleur has a curved cage that sits just above the chainrings. When moved in and out, that cage guides the chain onto different gears. The rear derailleur has a parallelogram, and a spring loaded arm with two pulleys. When shifted, the rear derailleurs upper pulley guides the chain across the cassette and onto the appropriate gear.
The shifters are designed to pull the cables that operate the derailleurs. Most bikes have them attached to the handlebar, but some older bikes will have them located on the downtube. The shifter on the right side of the bike controls the rear derailleur while the shifter on the left operate the front. For mountain bikes and hybrids there are really only two types, trigger and twist shifters. A trigger shifter uses thumb and trigger finger activated levers, while a twist shifter allows you to rotate a portion of the grip to shift gears. Road bikes usually have the shifter mounted onto the brake lever, but can also have paddle style shifters on the end of the bar or on the downtube.
Flat bar shifters come in two varieties, trigger (left) and twist (right)
Road bike shifters are usually attached to the brake levers (left) but on older bikes can be found on the downtube.
How To Shift Gears
Shifting your bike is easy to do and easy to do wrong. For all bikes that use derailleurs, remember one thing – Shift only when pedaling. The act of pedaling is what allows the chain to jump seamlessly from gear to gear. Also try not to shift both the front and rear derailleur simultaneously as it can lead to problems. To get comfortable shifting, pedal on a piece of flat ground and operate only the right (rear) shifter first. You will find that as you shift into higher numbers (assuming your shifter has a gear indicator) it will become more difficult to pedal but faster moving. Inversely, as you shift into lower numbers it will become easier to pedal but slower moving.
Once you feel very comfortable shifting the rear derailleur, shift into a middle gear and explore what the front derailleur does. You will notice that the incremental changes of the rear derailleur give way to large changes when shifting the front derailleur. Going across chainrings makes a huge difference in how easy or difficult it is to pedal. Once you have mastered the front and rear derailleurs, you are now ready to try shifting in other than flat conditions.
When to Shift Gears
The reason we shift gears is to give ourselves a mechanical advantage over the changing surroundings. With this mechanical advantage comes some idiosyncrasies. First thing is that the gears are designed to allow the chain to move easily from one to the other when shifted, but hold tight under the load of pedaling. What that means is that if you are pedaling with a great amount of effort (say up a hill), and try to shift, you are asking the drivetrain to both hold the chain in place and move freely. Sadly, it becomes difficult for a mechanical device to do both these things. To make sure you don’t run into any issues, always shift while you are pedaling with light load, or shift into the dear you will need just before you actually need it. As an example, shifting into a very low gear at the base of a hill is a better idea than taking a run at it and trying to shift down gears while your climbing under load.
Gear Ratios And How They Affect Your Ride
When we talk about gears, what it translates to is how many times the rear wheel rotates per pedal rotation. So if you are in a very low gear going up hill, you may pedal two complete pedal rotations in order to turn the rear wheel once. Inversely, if you are headed down a steep descent in a high gear, you will probably be spinning the rear wheel 3-4 times per pedal rotation. If you think about gears in these terms, it becomes easier to figure out where and when to shift.
Finding The Perfect Gear
The perfect gear is always changing (and you thought it would be easy). Even though it changes, it can most easily be described as the gear allowing you to pedal comfortably. We all have a natural pace (called cadence) we feel comfortable pedaling at, the goal in shifting I to allow you to continue to pedal at that pace even as the topography changes.
Putting It All Together
Now that you understand the “what, when, why, and how” of shifting, it’s time to practice on the open road. Pay close attention to what your most comfortable pedaling cadence is. Oftentimes people believe that they are comfortable pedaling really slowly in a difficult gear, but find after some experimentation, that they can pedal for longer if they shift into a slightly easier gear and pedal quicker. If you are riding off road, experiment with what gears give you the best traction on loose terrain. Many riders will default to their lowest gear at the first sign of loose conditions only to find that gear has too much torque, forcing their tire to break free and spin out. All in all, body types, muscle mass, conditions, and personal preferences make gearing choices different for everyone. But now that you know the details, you should feel comfortable finding the right ones for you.
Also check out our article on related tips to make your bike more comfortable and faster.