Disc brakes are better than rim brakes in almost every measurable way. More stopping power. Better modulation. Consistent performance in the rain. You no longer need to worry about carbon rim wear or wonder if your brake pads have turned to soap on a wet Alpine descent. The arguments for rim brakes in 2026 are mostly nostalgic.
But disc brakes come with their own set of annoyances, and those annoyances have a particular talent for showing up at the worst possible time. The morning of a sportive. Halfway through a group ride. The first wet descent after a month of dry weather.
Squealing. Spongy levers. Grinding that makes everyone behind you wince. The mysterious single-side rub that you cannot seem to fix no matter how many times you loosen and re-tighten the calliper.
The good news: almost all of it is preventable, and most of it is fixable at home with basic tools and about twenty minutes. You do not need to be a mechanic. You need to understand what your brakes are telling you and what to do about it.
Pad types: organic, sintered, and semi-metallic
Your pad compound matters more than most people realise. It affects bite, noise, heat management, wear rate, and wet-weather performance. Choosing the wrong compound for your riding conditions is like choosing the wrong tyre for the surface — it technically works, but everything is worse than it needs to be.
Organic (resin) pads
Organic pads — sometimes called resin pads — are made from materials like rubber, glass, carbon, and Kevlar bound together with resin. Shimano's B-series pads (B01S, B05S) and SRAM's organic compound pads are the most common examples.
They bite well from cold, which matters for the first braking effort of a descent. They run quieter than sintered pads, which matters for your sanity and the sanity of everyone riding behind you. And they modulate well — the progression from light braking to hard braking feels smooth and predictable.
The trade-off is wear rate. Organic pads are softer and wear roughly twice as fast as sintered pads in the same conditions. In the dry, you might get 3,000-5,000 km from a set. In sustained wet conditions — winter commuting, all-weather training — that drops to 1,500-2,500 km. Some riders chew through them faster than that on hilly terrain.
For dry-condition road riding, organic pads are the right default. Most bikes ship with them for good reason.
Sintered (metallic) pads
Sintered pads are made from metal particles — typically copper, iron, and graphite — fused together under heat and pressure. Shimano's D-series pads (D02S, D03S) and SRAM's metallic compound pads are the common versions.
They last significantly longer than organic pads, particularly in wet and gritty conditions. They handle heat better on long descents — sintered compound does not fade as readily when the rotor gets hot. And they maintain bite in the rain where organic pads sometimes feel like they have lost a third of their power.
The downsides: more noise, harsher initial bite (less modulation), and slower bedding in. Some riders find them grabby in dry conditions, especially at low speed. And they are harder on rotors — sintered pads will wear a rotor faster than organic pads will.
If you ride year-round in Britain or Ireland, commute in all weather, or regularly do long Alpine descents, sintered pads earn their place.
Semi-metallic pads
These sit between organic and sintered — a resin base with metallic particles mixed in. SwissStop's Disc pads and some of Jagwire's range fall into this category. They try to split the difference: better wet performance and longevity than pure organic, better modulation and lower noise than pure sintered.
In practice, they are a reasonable compromise if you cannot decide between the two. But most riders are better served picking organic or sintered based on their actual conditions rather than hedging.
Fin-cooled vs standard backing plates
Some pads — Shimano's Ice Tech range being the most prominent — come with aluminium cooling fins on the backing plate. These are not cosmetic. On sustained descents where the rotor gets hot enough to boil brake fluid (more on that shortly), the fins dissipate heat measurably faster. If you ride in the mountains, spend the extra $5-10 on finned pads. If your riding is flat to rolling, they are unnecessary.
Bedding in new pads: the ten minutes that prevent months of noise
New pads do not work properly out of the box. The pad surface is smooth and uniform. The rotor surface is smooth and uniform. There is no transfer layer — no thin, even coating of pad material deposited on the rotor — and without that transfer layer, braking is inconsistent, noisy, and weak.
Bedding in creates that transfer layer. It takes ten minutes and saves you weeks of gradually increasing pad performance interspersed with mysterious squealing.
The procedure is dead simple:
- Find a quiet, flat stretch of road or car park.
- Accelerate to roughly 25 km/h.
- Brake firmly with one brake — not an emergency stop, but a proper braking effort — and slow to about 5 km/h. Do not come to a complete stop. Stopping in one spot concentrates heat and deposits an uneven pad layer.
- Release and accelerate again.
- Repeat 20 times per brake.
- Let the brakes cool for a few minutes between sets of ten.
What you should notice: the first few stops will feel weak and possibly produce a metallic scraping sound. By the tenth stop, the bite should feel stronger. By the twentieth, it should feel sharp and consistent.
What you should see if you inspect the rotor: a faint, even discolouration where the pad has deposited material. This is the transfer layer. It is not dirt and it should not be cleaned off.
If you skip bedding in, the pads will eventually bed themselves through normal riding, but it takes much longer and you risk glazing — a hard, shiny surface that forms on the pad face when it overheats before the transfer layer has been properly established. Glazed pads squeal, offer poor bite, and need sanding to recover.
Thirty seconds of work to understand. Ten minutes to do. No reason to skip it.
Contamination: the silent killer of disc brake performance
Contamination is responsible for more disc brake problems than every other cause combined. A single drop of chain lube on a rotor can ruin a set of pads. A careless spray of GT85 near the wheel can contaminate pads that were working perfectly five minutes ago. Even handling the rotor with oily fingers after fixing a puncture is enough.
Brake pad material is porous. Once a contaminant soaks into it, the pad surface cannot generate the friction it needs against the rotor. The result is reduced braking power, terrible noise, and a grab-and-release pulsing that feels alarming at speed.
Common contamination sources
Chain lubricant overspray. This is the most common culprit. If you lube your chain with the wheel in the bike, drops flick off the chain and land on the rotor. Some chain lubes are designed to creep and penetrate — great for getting into chain rollers, terrible when they creep across your rotor.
Degreaser and cleaning products. Spraying the drivetrain with degreaser and not protecting the rotor. GT85, WD-40, and similar spray lubricants drifting onto the disc during general bike cleaning. Even "bike-specific" degreasers will contaminate pads if they reach them.
Finger oils. You fix a flat, handle the rotor when removing and replacing the wheel, and transfer skin oils to the braking surface. Trivial to do, surprisingly effective at causing noise.
Automotive brake cleaner. Counterintuitive, but some automotive brake cleaners leave a residue that disc brake pads do not tolerate. Use isopropyl alcohol, not automotive products.
New frames and forks. Manufacturing oils and cutting fluids can be present on new frames and forks, including around the calliper mount area. A new bike build should include cleaning the rotors with isopropyl alcohol before the first ride.
Prevention
Remove the wheel before lubing the chain, or at minimum position a rag behind the cassette to catch any overspray. When cleaning the bike, cover the rotors with a cloth or remove the wheels entirely. After handling rotors or pads, clean them with isopropyl alcohol before riding.
Keep a small bottle of isopropyl alcohol (90% or higher) in your tool kit. A quick wipe of the rotor surface takes ten seconds and prevents problems that take much longer to fix.
When to try to save contaminated pads, and when to bin them
Light contamination — a fingerprint, a faint trace of overspray — can sometimes be recovered. Remove the pads, sand the surface with 120-grit sandpaper until the shiny contaminated layer is gone, clean the rotor with isopropyl alcohol, and re-bed the pads.
Heavy contamination — a proper soaking from chain lube or degreaser, or contamination that has been ridden on for multiple rides — is almost never worth trying to fix. The contaminant has soaked deep into the pad material. You can sand the surface, but the material underneath is compromised. Replacement pads cost $15-30. Your time is worth more than trying to resuscitate pads that will probably squeal again within a ride.
When in doubt, replace them. Cheap pads, expensive consequences if they do not work when you need them.
Noise diagnosis: a systematic approach
Disc brake noise is not a single problem with a single solution. It is a symptom, and the cause determines the fix. Randomly trying things — tightening bolts, swapping pads, re-aligning the calliper — is a waste of time if you do not work through the causes in order.
Start here and work through the list. Stop when you find the culprit.
Step 1: Is it a constant rub or an intermittent squeal?
A constant rubbing or scraping sound — present throughout the wheel revolution — is a calliper alignment issue. The rotor is touching one pad at all times.
An intermittent squeal or howl under braking is a pad issue: contamination, glazing, or a pad that is not seated properly in the calliper.
Step 2: Calliper alignment (for constant rub)
Loosen the two calliper mounting bolts. Do not remove them — just loosen enough that the calliper can move laterally. Pull the brake lever firmly and hold it. While holding the lever, tighten the bolts alternately (one a quarter turn, then the other, repeat) until both are torqued to spec.
This centres the calliper over the rotor using the pads themselves as a gauge. Release the lever and spin the wheel. In most cases, the rub disappears.
If it does not, try the business-card method: slide a business card between the rotor and the non-rubbing pad, hold it in place, and repeat the loosening-and-tightening procedure. The card creates a fraction of extra clearance on the non-rubbing side.
If the rub persists, check whether the rotor is bent. Spin the wheel slowly and watch the gap between the rotor and pads from above. A bent rotor will visibly deflect toward one pad at one point in its rotation. Minor bends can be straightened with a rotor truing tool or careful work with an adjustable spanner. Significant bends usually mean a new rotor.
Step 3: Pad inspection (for braking noise)
Remove the wheel and pull the pads out of the calliper. Most modern callipers use a retaining pin or bolt that releases both pads and the spring.
Look at the pad surface. A healthy pad has a slightly rough, matte surface. A glazed pad is shiny, smooth, and sometimes has a slightly burnt appearance. A contaminated pad may look wet, discoloured, or have a distinctive chemical smell.
Glazed pads: sand the surface with 120-grit sandpaper until the shine is gone, then re-bed the pads.
Contaminated pads: try the sanding approach for light contamination. Replace for heavy contamination.
Worn pads: if the pad material is less than 0.5mm thick — roughly a credit card — replace them. Most pads have a wear indicator: a groove or line in the pad surface that disappears when the pad is worn.
Step 4: Rotor cleaning
Even if the pads look fine, clean the rotor with isopropyl alcohol and a clean cloth. Road film, brake dust, and invisible contamination accumulate on the rotor surface. A clean rotor paired with clean pads eliminates one variable.
Step 5: If nothing works
Persistent noise after alignment, pad inspection, rotor cleaning, and re-bedding points to one of three things: a warped rotor that needs replacing, pads that are contaminated deeper than the surface sand can reach, or a loose calliper adapter (the bracket between the frame and the calliper). Check the adapter bolts are torqued correctly. If all of that fails, take it to a good mechanic. Some problems really do need a trained eye.
Bleeding your brakes: when and why
Hydraulic disc brakes work by pushing fluid through a sealed system from the lever to the calliper. The fluid is incompressible, which is why the lever feels firm and the braking response is immediate. Air, however, is compressible. When air enters the system — through a seal that has degraded, during a pad change, or because the fluid has deteriorated — the lever starts to feel spongy. You pull it further before anything happens. In severe cases, it pulls all the way to the bar.
That is when you need a bleed.
Shimano vs SRAM: different fluids, different procedures
Shimano uses mineral oil. It does not absorb moisture, which means the fluid itself does not degrade meaningfully over time. The system is generally tolerant of long intervals between bleeds. If the lever feels good, you probably do not need to bleed it.
SRAM uses DOT fluid (DOT 5.1 in most current road and gravel groupsets). DOT fluid is hygroscopic — it absorbs moisture from the atmosphere through the seals over time. As moisture content increases, the fluid's boiling point drops, and performance degrades. SRAM systems benefit from an annual bleed even if the lever still feels acceptable, particularly if you ride in wet conditions.
This is not a knock on SRAM. DOT fluid has a higher boiling point than mineral oil when fresh, which is why SRAM uses it — it handles heat better on sustained descents. The trade-off is the maintenance interval.
What a bleed involves
A bleed pushes fresh fluid through the system, displacing old fluid and any air bubbles. Both Shimano and SRAM sell bleed kits ($25-35) that include syringes, fittings, and enough fluid for several bleeds.
The basic concept is the same for both: attach a syringe of fresh fluid to the calliper, attach an empty syringe to the lever, and push fluid through until it runs clear with no bubbles. The specific procedure differs — Shimano bleeds from the calliper up, SRAM has its own sequence — and getting it wrong introduces more air than it removes.
If you are comfortable following instructions and working slowly, a bleed is a 30-minute job. It is not difficult, but it is fiddly. Air bubbles are stubborn, and rushing the process usually means doing it twice.
If you have never done one and you are not mechanically inclined, take it to a shop for the first one. Watch what they do. Ask questions. The second time, do it yourself with the bleed kit and a YouTube walkthrough from the groupset manufacturer. Park Tool's and the official Shimano and SRAM channels have clear, step-by-step videos.
Signs you need a bleed
- The lever pulls noticeably closer to the bar than it used to
- The lever feels soft or spongy instead of firm and immediate
- You have recently changed pads and pushed the pistons back (this can displace fluid)
- You have not bled the system in over a year (SRAM DOT systems)
- The bike has been stored upside down or hung vertically for an extended period (air can migrate to the calliper)
If the lever feels firm and the brakes work well, leave them alone. A bleed is a maintenance procedure, not a preventive ritual for Shimano systems.
When to replace pads and rotors
Pad replacement
Pads are consumables. They wear down and need replacing. The question is when, and the answer is simpler than most people make it.
Thickness check: Remove the wheel, look at the pads in the calliper (or remove them entirely). The pad material — the coloured compound on the backing plate — should be at least 0.5mm thick. Most new pads are 2.5-3mm thick. When the material is down to 0.5mm or less, replace them. Some pads have a wear groove that disappears as an indicator.
By feel: If braking power has dropped and cleaning the rotor does not restore it, check pad thickness. Worn pads lose bite progressively, and because the change is gradual, you adapt without noticing until someone else rides your bike and tells you the brakes are terrible.
By sound: Metal-on-metal grinding — a harsh, gritty scraping that is unmistakably different from a squeal — means the pad material is gone and the backing plate is contacting the rotor. Stop riding and replace immediately. You are scoring the rotor surface, and a scored rotor needs replacing too.
Mileage guidelines: These vary enormously by conditions, terrain, and rider weight. As a rough framework:
- Organic pads, dry conditions, rolling terrain: 3,000-5,000 km
- Organic pads, wet conditions or hilly terrain: 1,500-2,500 km
- Sintered pads, dry conditions: 4,000-7,000 km
- Sintered pads, wet conditions: 2,500-4,000 km
Heavier riders and riders who brake hard and late will be at the lower end. Lighter riders who feather the brakes and brake early will be at the upper end.
Keep a spare set in your toolbox. Pads wear gradually, then suddenly — the last millimetre goes faster than you expect because the thinner pad flexes more and wears on an accelerating curve. Being caught with worn pads the morning of a big ride is entirely avoidable.
Rotor replacement
Rotors last much longer than pads, but they are not eternal. Every braking event removes a tiny amount of material from the rotor surface. Over thousands of kilometres, the rotor gets thinner.
Minimum thickness: Most rotors have a minimum thickness stamped or printed on them. Shimano rotors are typically 1.5mm minimum (starting thickness of 1.8mm). SRAM rotors vary by model but follow similar margins. A rotor that drops below minimum thickness is structurally compromised and risks cracking under the heat of a long descent.
How to check: Use a digital calliper to measure at the braking surface — not the spider or centre, but the outer ring where the pads contact. Measure at multiple points around the rotor to check for uneven wear.
Visual signs: Deep scoring or grooves in the rotor surface that you can feel with a fingernail. A pronounced lip at the edge of the braking surface where the pad does not reach. Blue or purple discolouration from overheating — this does not necessarily mean the rotor is done, but it indicates it has been stressed.
How long they last: A decent rotor — Shimano RT-MT800, SRAM CenterLine — lasts 15,000-25,000 km with proper pad maintenance. Running worn pads or sintered pads shortens rotor life. Running a contaminated pad that requires excessive force to achieve normal braking also accelerates rotor wear.
When you replace a rotor, bed in the new pads on the new rotor. Even if the pads have life left, the transfer layer on them matches the old rotor surface, not the new one. A fresh bed-in session takes ten minutes and gets everything working together.
The five-minute pre-ride brake check
You do not need to pull your brakes apart before every ride. But five minutes of checking three things will catch problems before they catch you on a descent.
1. Lever feel. Pull each brake lever. It should feel firm and engage the brake within the first third of the lever travel. If either lever feels spongy, pulls further than usual, or requires more force than you remember, investigate before riding. A spongy lever on a mountain descent is not something you want to discover in real time.
2. Pad clearance. Look down through the calliper from above with the wheel installed. You should see daylight between each pad and the rotor — a small, even gap on both sides. If one pad is touching the rotor, the calliper needs re-aligning. If both pads are close and the lever is pulling further than normal, the pads may be worn thin.
3. Rotor condition. Spin each wheel and watch the rotor pass through the calliper. It should spin freely without audible rubbing or visible wobble. A bent rotor or a misaligned calliper will be obvious. Give the rotor a visual once-over for contamination — oil spots, unusual discolouration, or a wet sheen that should not be there.
That is it. Lever, pads, rotor. Three checks, one minute per brake. It will not tell you everything, but it will tell you enough to ride with confidence or flag something that needs attention before you leave the house.
The bottom line
Disc brakes require more attention than rim brakes. That is not an argument against them — it is just the reality of a more powerful, more complex system. The maintenance is not hard. It is not expensive. It just needs to actually happen.
Keep your rotors clean. Bed in new pads properly. Do not spray lubricant anywhere near your wheels. Learn to recognise the difference between a calliper alignment issue and a contamination problem. Check your pads before they are metal-on-metal. Bleed the system when the lever tells you to, not on a fixed schedule.
Do those things and disc brakes are brilliant. Reliable, powerful, and consistent in conditions where rim brakes would have you white-knuckling every descent.
Ignore them and they will punish you with noise, poor performance, and a repair bill that could have been prevented with a cloth and some isopropyl alcohol.
If you want to talk through a specific brake issue with riders who have dealt with the same thing — or get a recommendation on pads for your groupset and riding conditions — the Roadman community on Skool is where those conversations happen. Bring the noise. Someone will have fixed it before.