Top 10 Disc Brake FAQs

Words by Harry Archer

on 15/05/2018 13:51:29

Top 10 Disc Brake FAQs

Disc Brakes have caused a lot of Disc-ussion since they first entered the MTB market a decade or so ago. Gradually increasing in popularity and implementation over the years , disc brakes are slowly becoming the new braking standard across almost every cycling discipline. Visit one of a Rutland Cycling store and you'll see discs pretty much everywhere - from hardtails to gravel bikes, high end carbon racers to full suspension beasties. The consistent performance, decreased maintenance and improved ability in terms of modulation and wet weather resistance are all contributing features in the development of disc brakes, allowing them to become the go-to option for many of the biggest brands within the cycling community. Even the final kingdom of the rim brake - high end road bike racing - is witnessing a shift towards disc based frames due to increasingly relaxed UCI regulations and the increased prevalence of race winners sporting disc brakes. Even institutions of the road such as the Specialized Tarmac, Giant Propel and Scott Addict RC have made the switch to disc brakes, showing just how far the innovation has gone in the highest echelons of cycling performance.

So, what do you need to know about these funky silver stopping rotors? We've put together a list of the top ten FAQs about disc brakes, giving you a quick run-through of all the important facts and busting some myths about discs. Lets get started.

What's the difference between rim brakes and disc brakes?

Rim, Calliper and 'V' braking systems were the go-to option for all disciplines within the cycling community for countless years and applying braking force directly to the wheel rim still reigns supreme for many in the traditional road scene, and entry level hybrid market. Disc brakes were first seen on mountain bikesm because of their increased stopping ability in wet weatherm and consistency in terms of braking force and modulation. Disc brakes apply the braking force to a rotor housed in the middle of the wheel, using either a cable or hydraulic based system, depending on the design, to stop the bike. As time has gone on and technology improves, discs have become more and more prominent on road, gravel, cyclocross bikes, with the last couple of years seeing top-spec bikes from the biggest companies sporting disc brake systems. Even on high-end premium road bikes and UCI registered competitions, disc brakes have become legal and widely accepted as the highest performing braking system available to all cyclists regardless of if they ride on or off the road. Whether you love them or you hate them, discs are here to stay and with the 'trickle-down' effect allowing increasingly effective systems on more affordable bikes, discs are well on the way to overtaking rims as the go-to braking system for the entire cycling market - whether that be at the entry, intermediate or professional level.

Our most popular disc brake bikes

What are the pros and cons of disc brakes?

Pros

  • Ride faster: The more consistent and reliable braking power of discs allows riders to brake fractionally later than they perhaps would on a bike with rim brakes. This means that the bike will maintain its speed round bends and reduced muscle fatigue whilst allowing for quicker overall ride times.
  • Consistency & reliability: As touched upon above, disc brakes provide consistent and responsive braking forces no matter the weather conditions or terrain. This gives the rider increased control over their braking and improves the riding experience directly. Additionally, the relatively sheltered position and larger surface area of Disc brakes offer unrivalled stopping ability in the wet. Rim brakes have to displace water from the rim before they can create enough friction to slow the wheel down - a disc brake does not suffer from this delay causing displacement and thus perform in exactly the same way come rain or shine.
  • Reduced wheel wear and maintenance: Unlike rim brakes, disc brakes do not come in contact with the wheel rims - meaning that your rims won't get worn down by heat, grit and dirt causing damage between the brake pad and rim service. This in itself reduces maintenance and when combined with the increased durability and stronger design of disc brakes (especially hydraulic disc systems) it's pretty much guaranteed you'll be spending less time with the tools and more time on the trails or tarmac if you make the switch to disc brakes.
  • Increased clearance: To accommodate for disc braking systems, rear hubs have to be widened and tyre clearance increased. This has led to the development of wider tyres on road bikes, giving better traction and comfort to the rider. It also allows the possibility to fit mudguards and racks - something previously unheard of in the road bike world due to the lack of space provided from traditional rim brake set-ups. This also means that braking won't be negatively impacted if a wheel is slightly unaligned, further increasing the versatility of disc brake systems.

Cons

  • Cost/weight: Although both of these issues are becoming less and less relevant as discs become more popular and innovations are implemented, it's still true to say that a disc brake system will add a small amount of weight to a frame whilst marginally effecting aerodynamics. Furthermore, disc bike frame options will often be more expensive than the rim brake equivalent and though they do last longer than rim brakes, the cost of replacing a disc system should it fail can be up to three times as much as simply replacing your worn out braking pads.
  • Non-transferable: Got rim brakes on your current bike? You can't just change to disc unfortunately. The different frame dimensions are not compatible between the two, with fork, wheel and hub set-up completely altered on disc brake specific frames. So you're committed to whichever system you primarily go for until you buy a new bike - unless you buy from Rutland Cycling, our 30-day return policy will see you right if you make a mistake on your initial choice of brake set-up.

Are disc brakes heavier than rim/caliper brakes?

In the past this was one of the major arguments, particularly amongst lycra lovers, against the wider implementation of disc brakes onto road brakes. However, due to the massive amounts of refinement and innovation put into disc brake systems and their integration on bikes over the last couple of years, new disc-specific bikes are lighter than ever, coming in very close to the UCI minimum limit. All of the big brands like Specialized, Scott, Giant and Trek now boast bikes that are disc compatible and barely reach the UCI minimum weight limit! As the weight issue becomes less and less relevant, you can be sure to see the pro teams adopt disc brake frames due to the aforementioned advantages of increased reliability,accuracy and overall speed.

Guide to Road Disc Brakes >

bianchi-impulso-eroad-electric-road-bike-3

Are disc brakes safe?

The argument here is that disc brakes are sharp and can get so hot that they can actually burn riders should their skin come in contact with the braking surface. The issue is compounded by races where both rim and disc frames are in use and riders are riding in large groups close together with totally different braking times and effectiveness - leading to crashes at tight corners and putting riders at an increased risk of injury. However, the new innovations in disc design have improved the safety of the systems and many of the fears about disc brakes in pro-races have been unfounded. Furthermore, the UCI now requires disc rotors to have a rounded edge to prevent the possibility of 'slicing' injuries. What is clear to see is that as the use of discs goes up, the level of accidents and injuries have shown no obvious increase and so gradually, as disc brakes are used in more and more races without catastrophic results, the safety concerns surrounding them begin to diminish. For casual riders, disc brakes don't provide any real safety issues, just be careful not to put your finger near one that's spinning!

What are the differences between hydraulic and mechanical disc brakes?

Although both types of disc will look and perform with many similarities, there are some key differences between the two systems that are important to take note of. These differences including piston design, construction material and the way in which the force applied to the brake levers is transferred to the brake rotors.

Mechanical - This type of disc brake is often cheaper and commonly found on entry-level disc brake frames. Mechanical discs use a steel cable to move the pistons and create the braking force. The advantages of this set-up is the ease of maintenance, a lighter overall weight and simple installation. However, mechanical systems can also be prone to stretched cables reducing braking power and binding of the braking system due to debris entering the cable housing.

View All Mechanical Disc Bikes >

Hydraulic - This type of disc brake is viewed as the higher performing and more reliable option and utilises a fluid based system rather than cables. The fluid is pushed into the caliper when the brake lever has force exerted upon it and allows for excellent braking modulation, accuracy and consistency. Hydraulic systems tend to feel smoother and are less prone to failure compared to mechanical equivalents. They are also sealed to prevent the build up of debris and dirt which can compromise their effectiveness. That being said, hydraulic disc brakes have to withstand a lot of pressure and therefore proper set-up is vital and regular maintenance checks are required to ensure the continued performance of the system - the smallest leak or air bubble in the hydraulic brake can cause serious loss of power or even total failure, with the only fix a brake 'bleed'. Bleeding brakes can be fiddly so expect to have to visit your local bike workshop to get this done unless you are particularly savvy with your in-house bike mechanics.

View All Hydraulic Disc Bikes >

trek-bikes-trek-remedy-mountain-bike-mtb-hero

Do disc brakes require 'bedding in' before they'll work properly?

This is something to definitely bare in mind should you be looking at purchasing a brand new disc brake bike. All new disc brakes, whether they be mechanical or hydraulic systems, will require a breaking-in period in which their performance will not be at the optimum level. The reason for this is that the external surface of the brake rotor needs to be roughened in order to allow the brakes to perform properly and create enough friction to stop effectively. The brake pad material also needs to become embedded in the rotor for the discs to work how they should. This issue is easily addressed - simply take your bike out for a quick spin post purchase and regularly apply gentle pressure to the brakes without coming to a complete stop. Repeat this exercise a number of times over a 10-15 minute period and by the end you'll have fully bedded in brakes that are 100% ready to go out and tackle the steepest descents you can throw at them!

Do disc brake rotors come in different sizes?

They most certainly do - the size of rotor that you'll need depends on a number of factors including:

  • Where are you riding? Riding on changeable terrain with lots of big drops and fast descents? You'll want to go for larger rotors as these have a larger surface area and thus higher levels of stopping ability. Riding on the road or relatively flat singletrack? Smaller rotors should be perfectly sufficient and still offer excellent braking qualities. Aggressive riders may want to go bigger to support the increased forces they're putting through the frame/braking systems whilst for those that climb regularly or are weight conscious, smaller rotors are more suitable.
  • How much do you weigh? Heavier riders take more force to stop - it's a simple rule of physics and something to certainly consider when selecting your rotor size.
  • What do you ride? - A key consideration. Suspension travel, wheel size and design purpose all play a major role in deciding which rotor diameter you'll require. Mountain bikers and heavier riders, those rocking 29" wheels and downhill riders will want to go big rotor wise, whilst XC and road riders will probably opt for smaller options. Remember to check that your bike's frame/forks can accommodate the rotor size you want - many models don't have enough clearance on the chain and seat-stays to allow for rotors over 160mm whilst some short-travel suspension bikes won't accommodate rotors bigger than 180mm.

Most brands offer 4 or 5 rotor sizes across their road and mountain bike ranges - depending on the bikes intended usage and frame geometry. Large rotors resist heat better and provide better modulation whilst smaller rotors are lighter, less exposed to debris and don't rub as much so it's very much a personal choice, with larger/smaller rotors both having their advantages and disadvantages. It's always better to have it and not need it than need it and not have it, so if in doubt go bigger rather than smaller.

My disc brakes are making a strange noise, why is this happening?

If your disc brakes emit a 'squealing' sound when put under pressure then it's likely that this is being caused by moisture or dirt contaminating the braking pad. The brake rotor cannot create enough stopping force if it cannot grip properly and this will cause the squeal because the system is having to work harder to bring you to a stop. A quick clean of the system should do the trick and get you on your way squeal free - should the noise remain despite cleaning then something is likely to have gone wrong and you'll need to replace your rotors or at the very least take your bike to a local workshop to be checked over by a mechanic.

A constant banging type sound coming from a disc brake is likely to be caused by an improperly positioned rotor. Rotors can become warp by heat, hubs can shift by minor amounts in the dropouts and the dodgy quick release skewers can cause small movements in the braking system as you ride along - all contributing to the banging noise. Normally this can be fixed by waiting for the discs to cool or via a simple wheel realignment - the increased prevalence of thru-axles should remove this problem in the future as these axles are far stronger and rigid and prevent wheel movement and subsequently rotor rub.

specialized-venge-aero-road-bike-10-sml

Has the increased use of disc brakes led to other market changes?

Quite simply - yes it has! The increased implementation of disc brake systems has meant numerous changes to certain frame designs and the creation of a whole new category of road bike: the all terrain road bike liek the Specialized Diverge, Trek Checkpoint and Giant Revolt. Removing the brakes from the seatstays and the increased tyre clearance this creates has allowed wider profile tyres and rims to be fitted onto traditional road bike frame designs, with manufacturers no longer restricted to 25mm tyres, instead opting for 28-30mm tyre/rim set-ups and improving both the comfort of the ride and the grip/traction of the tyres - ideal for 'all-road' model concepts. Disc brakes have also meant the re-designing of wheels, removing the rim brake issues of wear on the rim compromising strength and damage to the tyres and inner tubes due to excessive heat build up. By moving the braking force into the centre of the wheel, designers are able to focus on aerodynamics and tyre holding qualities instead of having to reinforce the rim to counter the wear caused by rim brakes. They're also able to remove material from the seat-stays as they no longer have to accommodate braking systems - allowing for more compliant frames to be produced, which is always a good thing.

Summary

The brakes you choose for your bike is an individual decision that only you can make. Rim brakes still have their place and if you find they work best for you then that's fine - rim systems aren't likely to completely disappear any time soon because they're so light and in a market where weight is everything, those marginal gram gains will still appeal to a large group of cyclists that live for speed and aerodynamics. However, as time goes on, standards improve and prices drop you can expect to see discs featured on a wider selection of bikes all the way down to entry level. For the average rider this is good news as the consistent braking and all-year performance will improve safety during the commute or weekend ride and the additional weight isn't really much of an issue. Disc brakes are certainly here to stay and are only going to improve - so come and visit us in store, try one for yourself and see if discs are for you!

View full range of disc brake bikes >

Find your nearest Rutland Cycling store

Got more questions about disc brakes, or want to take a closer look at the newsest models? Visit your nearest store and talk to our expert team.

THE RUTLAND DIFFERENCE

FREE DELIVERY OVER £10

EASY RETURNS

30-DAY TEST RIDE

0% FINANCE