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BUYER'S GUIDE

Everything you need to know about disc brakes - read our definitive guide

If you've been left behind by the whole disc brakes on road bikes thing, we'll get you up to speed

Disc brakes have been used on the road for years but in the last couple of seasons they've become mainstream as major bike makers have offered disc-equipped bikes covering all sectors of the market from gravel bikes to endurance bikes to full-on road race rigs. With the UCI now allowing them in the professional peloton, discs are an ever more familiar part of the road riding landscape.

  • Disc brakes provide better stopping power than rim brakes, especially in wet or cruddy conditions

  • A bike with disc brakes will still be rideable with a broken spoke or damaged rim, problems that can stop a rim-braked bike dead in its tracks

  • They're more expensive, but disc brakes with hydraulic hoses to get braking force from lever to pad work better than cable-actuated systems

  • Semi-hydraulic calipers like TRP's Hy/Rds are a sensible compromise upgrade

9 of our favourite disc brakes

What are the advantages of disc brakes?

Let’s start right at the beginning. We’re all familiar with traditional bicycle rim brakes where the brake pads operate on the wheel’s rim, right? With a disc brake the pads instead act on a metal rotor that’s attached to the wheel’s hub. Simple enough.

What’s the advantage of that? People sometimes say that they can easily lock up the wheels of a road bike, stopping them totally with very little effort, so there’s no point in having any more power.

One key point is that disc brakes can offer more control than rim brakes before they lock up. You have more of a braking range with which to work, so you’re less likely to skid.

SRAM Rival 22 Hydro groupset - brake calliper on bike

SRAM’s Product Manager Paul Kantor told us, “I can certainly lock up my wheel with a carbon rim and a mechanical rim brake, but if I do that I’m still just sliding down the road and that sucks. Locking up the wheel isn’t hard but if that were our goal we’d just sell you a stick that you could ram in there and you’d be done!

“Everything we’ve focused on is prior to locking up the wheel. You can take off more speed with greater control prior to locking up the wheel. Some people refer to that as ‘modulation’. That’s a term we don’t really care for, but it’s fine. We’re really talking about decelerating substantially without locking up the wheel.”

Check out what big bike industry names thought about the introduction of disc brakes on road bikes from a couple of years ago.

With a rim brake system, you want the wheel rim to be as light as possible, you need it to be strong, and it also has to provide the braking surface. Anyone who has ever ridden carbon-fibre rim brake wheels knows that while they might be lightweight and fast, the braking performance isn’t brilliant, especially in wet conditions.

Shimano SM-RT81 rotor

A disc brake system allows manufacturers more scope to innovate with the braking surface because it doesn’t need to operate as the wheel rim too. Shimano, for example, equips its hydraulic disc brakes with what it calls Ice Technology that features a rotor with a three-layer sandwich structure of stainless steel and aluminium. It says that this provides a better radiation performance that reduces the temperature while braking.

SRAM 1x Germany 2015  - 2

Plus, with a disc system the braking surface, the rotor, is much further from the road than it is with a rim brake so it’s less likely to get wet from surface water. There are holes in a rotor that allow water to get out from underneath the brake pads too. The result is that disc brakes are far less likely than rim brakes to be affected by water or gunk thrown up from the road.

With a rim brake, the tyre has to pass through the brake calliper, but that's not the case with discs, so they free up space for wider tyres. That's part of the reason why discs have become popular for endurance and adventure bikes.

Linked to that, a side benefit of disc brakes is that your wheel can go out of true without rubbing on the brake pads.

Mechanical or hydraulic disc brakes?

You can divide disc brakes up into two types: mechanical and hydraulic.

Mechanical systems are operated by a cable, like the vast majority of rim brakes, while hydraulic systems use fluid to transfer the force from the lever to the calliper.

Pulling the brake lever in a hydraulic system moves a piston inside the master cylinder which forces brake fluid towards the brake calliper. This acts on the pistons in the brake calliper to push the brake pads against the disc rotor.

TRP Spyre mechanical disc brake

Mechanical disc brakes tend to be cheaper. TRP’s Spyre mechanical disc brakes, for example, are priced £69.99. You can use them with standard (non-hydraulic) dual-control levers. The Spyre is a dual piston design meaning that two pistons move equally against the rotor, as opposed to the single piston design of the Avid BB7 and Shimano CX75 mechanical disc brakes.

SRAM Rival 22 Hydro groupset - shifter

Hydraulic brakes are higher end and they perform better than either rim brakes or mechanical discs in just about every respect, but they’re more expensive. A SRAM Rival 22 hydraulic disc brakeset (you get both the shifter and the brake calliper), for example, is £302.

If you're concerned about maintenance, check out our guide to bleeding SRAM’s hydraulic road disc brakes. It's pretty straightforward.

Hydraulic systems are more efficient than mechanical disc brakes so you need to apply less pressure at the lever for an equal level of braking power. This means you can get better modulation.

A hydraulic system is sealed so no contaminants can get in to affect braking performance, and complicated internal cable routing isn’t a problem, whereas it can add friction to a cable setup.

TRP HyRd disc brake - front

TRP’s Hy/Rd brakes are unusual in that they’re cable operated with hydraulic power in the callipers. We found them powerful, easy to live with, and the best solution so far for disc brakes with conventional brake/gear levers.

What about heat?

Whatever type of system you use, braking produces heat. There used to be concerns about the safety of carbon rim brake wheels during prolonged, heavy braking – we’re talking about Alpine-style descents here – but manufacturers seem to have got that technology sorted.

When it comes to discs, fade (the loss of braking power) can occur as a result of the buildup of heat in the system.

Shimano identified overheating as being of particular concern for discs on the road, the longer, faster descents (and smaller rotors) being likely to result in rotors and pads heating up more than they do off-road.

Cannondale Synapse Carbon Ultegra Disc - front disc

As mentioned above, to counter this Shimano’s IceTech rotors use a three-layer sandwich structure of stainless steel and aluminium, the aluminium being included because it transfers heat better than steel. These have wavy aluminium sections inboard of the brake track designed to maximise surface area for improved cooling. The pads have cooling fins that are made from aluminium for the same reason.

Check out the hottest disc-equipped road bikes.

SRAM RED 22 HRD Brake (2).jpg

Speaking about the development hydraulic brake systems, SRAM’s Paul Kantor said, “Where you might have trouble is with some big guy riding down the Stelvio for 45 minutes dragging the brake, and we were worried that we’d have boiling issues there. But what happens is that the brake reaches a steady state where the heat isn’t increasing.

“What we did see is that when we decelerated from 50-60kph down to 15kph in 1-2 second increments on a switchback descent there was friction fade where you’d lose some of your coefficient of friction in the pad. That is much better than having the system boil.

“We could induce this on a 140mm rotor so we altered the backing surface on the pad to dissipate that heat way better. So now we have a very small window where you could induce some friction fade if you were really trying to do it but we have had next to no issues with boiling the system.”

Disc size

Discs are available in different sizes. All other things being equal, a large disc will slow you down faster than a small disc.

Shimano's road disc brake system has been designed for use with 140mm or 160mm rotors, the idea being that users can choose the size to suit their weight and intended use.

Trek Crockett 7  - SRAM disc brake

SRAM’s Paul Kantor said, “We recommend 160mm rotors front and rear for road use and 140mm is fine for cyclocross. We have tested 140s extensively but we like the margin of safety that 160s offer for the road.”

Focus has told us that in testing it found 160mm rotors preferable to the more common 140mm, handling the buildup of heat more effectively. This goes against the trend for smaller rotors, which is largely the result of Shimano recommending 140mm rotors for all but the largest cyclists.

The choice is yours but if you’re a larger rider you might want to start with 160s and see how you go.

Mounting standards

There are different standards for fixing disc brakes to road bikes but Shimano’s road-specific Flat Mount system, announced in 2015, is becoming dominant.

Shimano BR-RS805 calliper

"This new design allows consumers to move away from the mountain bike history and look, which has been used until now, using a method better suited to high performance road bike riding,” says Shimano.

Shimano’s Flat Mount is an open standard meaning that other manufacturers are free to use it. SRAM has recently adopted it too.

Shimano BR-RS805 calliper rear threequarter.jpg

With Flat Mount the brake callipers attach directly to the frame or fork, offering a cleaner and more minimalist appearance than with a post mount system. It also provides a more compact packaging of the brake calliper, which is a particular benefit at the rear triangle.

focus izalco max disc 38

The bolts thread into the bottom of the calliper rather than in from the top as is the case with post mount brakes. At the chainstay that means the bolts no longer thread into inserts in the frame, but pass through the chainstay from the bottom so there’s less chance of damaging an expensive carbon frame. Because the bolts thread in from the bottom of the calliper, the front brake must be used with a slim adaptor.

Quick release or thru-axle?

A disc brake puts forces on a wheel that are different from those of a rim brake, so keeping that wheel in its correct position and avoiding flex in the axle and dropout become challenging.

Focus Izalco Disc 2016 12

One way to keep the wheels in place is to use thru axles where the ends of the dropouts are closed and a removable pin goes completely through the axle to hold it in place. This adds security but it also adds a little weight and makes swapping wheels a touch more difficult.

Focus Cayo RAT 2

Focus has come up with what it calls Rapid Axle Technology – RAT, for short – design to simplify the process. The RAT thru-axle is a design that requires just 90° rotation of the axle in the dropout to close the lever.

Pinarello Dogma Disc 01

Some disc brake road bikes still use standard quick releases, like the Triban RC 520 but most use thru axles, like the Focus Izalco Disc. Others go with one quick release and one thru-axle. We’re still in a period of change and it’s not clear how the market is going to settle, or whether it will settle at all; it could be that different manufacturers continue to use different systems.

Focus Izalco Disc 2016 1

Aerodynamics

Many road bikes these days are designed with a focus on aerodynamics, partly because the UCI has a 6.8kg minimum bike weight limit for racing. There’s little point in a manufacturer focusing on bringing down weight but it can reduce drag in order to gain an advantage. How do disc brakes fit into this picture?

For a few years now bike manufacturers have been working on incorporating discs so that they are as aerodynamically efficient as possible.

When Giant introduced the latest version of its Propel aero road bike it said, “Engineers... found that, with proper integration, a disc-brake design can actually improve aero performance compared to rim-brake configurations.”

That was a significant claim because one of the arguments often put forward against disc systems was that they increased drag. 

“This is because the location of traditional callipers (either in front or behind the fork crown/ legs) creates 'dirty' air," said Giant. "Opening up the fork crown area (by placing the disc-brake callipers down at the hub) means that the air hitting the new disc-brake calliper has already been disrupted by the leading edge of the tyre/wheel. This effect is further enhanced by an asymmetric fork that helps smooth out airflow over the calliper.”

Other manufacturers have since claimed that they can make disc brake bikes that are at least as efficient as their rim braked alternatives, and many top-end bikes are now available only with disc brakes – there is no rim brake option.

The professionals

Like it or not, what the professionals ride has a massive influence on the road bike market. After all, that’s the main reason that sponsorship exists. When pro riders use a particular product others follow, and that’s why it’s so significant that the UCI allows disc brake equipped road bikes in the peloton.

Bernie Eisel disc brake 1

Pro teams were initially allowed to try out disc brakes in races towards the end of the 2015 season and after some ups and downs they're now permitted.

There's still some resistance to discs among pros, and there have been claims of riders sustaining injuries from disc rotors in crashes, so we may never see universal adoption of discs, but superior bike control on descents and in the wet may sway the skeptics.

That said, a some notable riders are very much rim-brake hold-outs. All three 2020 grand tours were won on rim-brake bikes: The  Tour de France by Slovenian phenomenon Tadej Pogačar of UAE Team Emirates on a Colnago; the Giro d'Italia by British rising star Tao Geoghegan Hart of Ineos Grenadiers on a Pinarello; and the Vuelta a España by Primož Roglič of Jumbo–Visma on a Bianchi.

All three teams' bike suppliers make disc brake bikes, and Ernesto Colnago is on record as saying that he believes discs are superior, but for racing the decision still comes down to weight.

Colnago engineer Davide Fumagalli confirmed this to Ben Delaney of Velonews. Fumagalli said the disc-brake version of the Colnago V3Rs weighs 6.95kg, the rim-brake version a little under the UCI 6.8kg limit. That gives riders  “more mental freedom to choose wheels, tire, etc.,” he added. That 150g margin might not sound like a big deal, but it's worth a few seconds on a major climb and those seconds add up.

rotor uno being raced

Whether or not road racers are ever fully won over by disc brakes, brands will almost certainly encourage teams to use them as a way of legitimising and validating the technology in the eyes of the bike buying public, and ultimately selling more disc brake road bikes.

Recommended disc brakes

Whether you’re looking to upgrade or thinking your next bike will have discs, here’s our selection of the disc brakes we currently favour.

Shimano Tiagra ST-4720 STI & BR-4770 brakes — £187.99/brake & lever

Shimano Tiagra 4720-3.jpg

Shimano's Tiagra Disc levers and callipers are what you should look for on your next commuter or winter bike. They have one less speed than 105 but apart from that you'd be hard pressed to tell the difference without a set of scales. The setup is reasonably easy, and they're light on maintenance and easy to bleed. If you really can't live without 11 speeds at the back they won't be for you, but given the quality of the shifting and the braking, they're a great choice.

Tiagra is a ten-speed groupset, so these brakes will only be useful to you if you already have a Tiagra-equipped bike. However, that covers an awful lot of bikes, as Tiagra bikes with disc brakes almost always come with cable-actuated discs.

Read our review of the Shimano Tiagra disc brakes

TRP Hylex RS brakes — £130 - £140

TRP Hylex RS -4.jpg

If you don't have a disc brake-equipped singlespeed bike then you're obviously missing a niche: go out and buy one immediately. If you do, then obviously you'll know they're great. You don't have many options if you want a full hydraulic system on your disc-equipped singlespeed: there's this TRP Hylex system... erm, and that's about it. The good news is that it's an excellent system: easy to fit and service, with plenty of power and modulation available. And if you're looking to build a 1x Di2 bike then you can use Shimano's climbing shifter to make the Hylex Di2 compatible.

Read our review of the TRP Hylex RS brakes

Shimano 105 R7020 — £525.00/set

Shimano R7000 hydraulic -2.jpg

The first Shimano 105-level disc brakes were pretty good, but with the new hydraulic system, the R7020 lever and the R7070 calliper, Shimano has upped its game significantly. They're still quite expensive as an upgrade, but definitely one to look out for if you're in the market for a new disc-braked road bike.

The new R7020 lever is a full redesign, it's nothing like the outgoing lever. The shape is very much based on the mechanical lever, with the same lever design and a similar hood profile with the textured finish for better grip in the wet. The body of the hood is a bit bigger, especially at the bottom where the hose exits the lever, but it doesn't have the annoying bump that the RS505 lever did: it's a much better overall shape. The extra width of the lever at the bottom meant that the bottom of the hood sat away from the bar tape a bit; it was noticeable close up but not really an issue.

Shimano R7000 hydraulic -1.jpg

The 105 brakes work brilliantly out of the box, and they're almost entirely fuss-free. These brakes bite when you'd expect them to in the lever travel, and from there there's masses of stopping power available as and when you need it. The reach is adjustable, but there's also a new, smaller lever (R7025) that should be ideal for those with smaller hands. The amount of effort you have to put in to control your speed on the steep, loose back road descents round here is genuinely a revelation compared to rim brakes or mechanical disc brakes.

Once you've got used to the bite point and the amount of squeeze you need, they make difficult roads simple: that's the reason good hydraulics are the best brakes.

Read our review of the Shimano 105 R7020 hydraulic disc brakes

TRP Spyre Mechanical Disc Brakes — £43.00 - £79.99

TRP Spyre Mechanical Disc Brakes

Buy a mid-range disc brake equipped road bike or cyclocross bike at the moment and there’s an extremely high chance you'll end up with a pair of TRP Spyres bolted to it. In the tidal wave of new disc bike drop bar bikes appearing on the market, the Spyre has become the benchmark for ease of setup, use and reliability. These are excellent, quite possibly the best mechanical disc brake solution out there - more expensive than its predecessor but less expensive than hydraulics.

Check out our review here.

Yokozuna Motoko — £285/pr

Yokozuna Motoko Disc Brake - fitted 2 .JPG

The Yokozuna Motoko disc brake calipers are the lightest option for cable-actuated hydraulic braking. They're easier to set up than their TRP HY/RD rivals, better-looking, include compressionless cables, and have better tool-free adjustment and no performance drawbacks. If you can fit them to your frame with no clearance or cable routing issues they are a great choice as an all-inclusive cable-and-caliper offering.

Read our review of the Yokozuna Motoko disc brake

TRP Hy/Rd mechanical interface hydraulic disc brakes — £75.00/brake

TRP HyRd disc brake - rear

TRP Hy/Rd disc brakes combine cable actuation with hydraulic power right in the calliper. They're powerful, easy to live with and the best solution so far for disc brakes with conventional brake/gear levers. After a month or so testing these brakes in all conditions, we found them to be more powerful and controllable than rim brakes and easier to set up and maintain than mechanical discs, and they win over stem-mounted converters in their simplicity with no noticeable loss in performance.

The price and link above is for post-mount brakes. Flat mount brakes are £80 each when available.

We can't currently find a UK source for HY/RDs at all. If you want to take your chances with the post-Brexit trade barriers, you can get them from Decathlon Belgium for €80 including rotor

Check out our review here.

Shimano RS-505 hydraulic discs — £524.99/pair

Shimano 105 hydraulic - callipers 2.jpg

These are the first '105-level' discs that Shimano offered and they're pretty good, although the new 105 R7000 brakes are tidier. You get the front and rear shifters, disc callipers, pads, cables and hoses included in the package. The callipers are more compact than the post mount ones and they come with Ice-Tech resin pads with heat-sink fins to help with cooling. The front brake has a reversible plate that allows you to run either a 160mm or 140mm rotor at the front. the rear flat mount calliper bolts directly through the frame if you're running a 140mm rotor; if you want a 160mm at the back you need an extra plate between the calliper and the chainstay.

Like the BR-785s below, these are discontinued, but if you encounter them on a secondhand bike, they're well worth a look.

Read our review of the Shimano RS-505 disc brakes

Shimano BR-R785 Di2 road hydraulic discs — NA

Shimano BR-R785 road hydraulic discs - rear disc

These were a very good first incarnation of road hydraulic braking from Shimano. When we first teted them we said: "In use, the brakes are really excellent, with significant improvement in modulation compared to mechanical rim brakes. We racked up hundreds of horrible, wet, dirty commuting miles with these and they brakes operated reliably throughout with no reduction in power or control. If you can afford them, these brakes are very much recommended. They're not without their glitches, but they outperform rim brakes in pretty much every situation."

They're long discontinued but if you find a second hand bike fitted with them, they're a fine option.

Check out our review here.

SRAM Rival 22 shifters/hydraulic disc brakes — £231.20 - £245.65/brake

SRAM Rival 22 Hydro groupset - disc brake on bike

SRAM's Rival 22 hydraulic groupset is the lowest tier of its road disc line-up, but for many it provides the ideal combination of performance and price to fit to an all-purpose bike. The hydraulic levers look bulky, but ergonomically they're easy to use and comfortable (with a caveat if you have really small hands). The braking offers great modulation and plenty of power for very little effort. We did get some fade when we dragged one of the brakes on a two-mile descent. Trying to cook both brakes at the same time was impossible: if you're generating enough heat to affect the system then you'll be at a standstill in no time.

Check out our review here.

Explore the complete archive of reviews of brakes on road.cc

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Mat has been in cycling media since 1996, on titles including BikeRadar, Total Bike, Total Mountain Bike, What Mountain Bike and Mountain Biking UK, and he has been editor of 220 Triathlon and Cycling Plus. Mat has been road.cc technical editor for over a decade, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. He has won his category in Ironman UK 70.3 and finished on the podium in both marathons he has run. Mat is a Cambridge graduate who did a post-grad in magazine journalism, and he is a winner of the Cycling Media Award for Specialist Online Writer. Now over 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

Add new comment

72 comments

Avatar
Morat | 6 years ago
9 likes

I like disks. I don't care what anyone else rides as long as they're having fun.

Avatar
Russell Orgazoid | 5 years ago
1 like

Spinning discs of death...remeber all that guff?

Avatar
pmurden | 5 years ago
2 likes

They're a bit heavier. Perform way better in all conditions. Open up oportunities for better aero. Bosh

Avatar
Dingaling | 5 years ago
3 likes

I have just spent the last couple of weeks ( there was no need to rush) stripping my mtb down to the frame and cleaning everything. I replaced badly scratched spokes on the drive side of the rear wheel and, when one aluminium spoke nipple split, I decided to replace all 32 with brass ones.  That necessitated getting nipples with square heads and a tool to match. All took more time than usual. Eventually I got to the disc brakes. Never have I had a problem with rim brakes (cantis, v-  or caliper) other than changing the pads for very little money. Not so with my Avid Elixir. They have always had a tendency to rub and make a noise and earlier this week I find that a piston in both calipers hardly moved. I've blocked the good piston to make the other move. I've cleaned them and when that didn't work I taken the calipers apart and cleaned everything. None of it has done any good so I've taken the advice found on forum threads "bin the Avids and get Shimano/Hope etc"

I have now ordered Hopes with a new front disc (down from 185 mm to 180) and a new pm/pm adapter. So that will be around €350  to fix a problem with disc brakes. Way more than I have spent on servicing rim brakes in more than 30 years. 

My point is, if you are happy with rim brakes, then stay with them unless you are prepared for a whole set of different problems servicing disc brakes or even just shortening the hydraulics.

Avatar
Joe Totale | 5 years ago
2 likes

What often isn't mentioned is the extra cost of a disc brake system. 

If money is no object then a disc brake equipped bike would definately be the way to go, at the top end of things there's barely any weight difference coupled with performance benefits. 

In the real world though where money matters, you can still build a high performing rim brake bike for a lot cheaper than a disc one. For example a disc brake frame which is the same weight as a rim brake one is usually significantly more expensive, the same is true of wheels. 

Shimano R7020 is retailling for £60-70 more than R8000. The Ultegra rim brake groupset is around 500 grams lighter then the 105 disc one which may not mean much to some riders but for others that's a huge weight saving and one which will lead to performance benefits in other areas such as climbing. 

Avatar
itchieritchie | 5 years ago
0 likes

 

These comments leave me somewhere in the middle of both camps in terms of experience. 

I have a Trek Domane with rim brakes. Happy with it and I've never tried discs. On a road bike at least. I do miss discs from my MTB days though. 

So I'd be happy to convert to discs. Currently run 10-speed Shimano Ultegra. Anyone know if it would be possible to just switch out the front rim for a flat mount? Only because it would be good to keep costs down and most of the braking forces happen at the front anyway, don't they? I wouldn't be ashamed of sporting a hybrid Franken-brake-monster either as I always go with function over form. 

Aside from the lever, I'm assuming I'd need a new and compatible set of forks too. And the wheel, obvs. 

Avatar
Libtardproud | 4 years ago
1 like

My 18+ yr old Ti softtail MTB with 26" Mavic wheels, 2.2" tires, and V-brakes, weighed under 25 lb. I've become more wary, and have over the years upgraded the front fork, added just front Avid BB7 brake, beefier wheels needed for the disc, and the widest tires I can fit into the frame, 2.5", run at about 18 psi, tubes, zero flats in four years. The same bike now weighs over 28 lb. I am far more able to confidently ride technical terrain, but really feel the weight uphill. Sigh. The V-brake rear is perfect, light, and keeps me from trail-destroying skids, and most stopping is front anyhow. Discs might be the ticket on gravel/grunge bikes, but way too heavy for road consideration and alloy rims just work fine. As do 2 chainrings.

Avatar
fixit | 4 years ago
1 like

road.cc must set a limit for article "Everything you need to know about disc brakes" per anum.

Avatar
47steve | 3 years ago
0 likes

Love disc brakes but when re fitting wheels it's always tricky to get them to re seat without the pads rubbing on the disc

 

Avatar
fenix replied to itchieritchie | 5 years ago
2 likes
itchieritchie wrote:

 

These comments leave me somewhere in the middle of both camps in terms of experience. 

I have a Trek Domane with rim brakes. Happy with it and I've never tried discs. On a road bike at least. I do miss discs from my MTB days though. 

So I'd be happy to convert to discs. Currently run 10-speed Shimano Ultegra. Anyone know if it would be possible to just switch out the front rim for a flat mount? Only because it would be good to keep costs down and most of the braking forces happen at the front anyway, don't they? I wouldn't be ashamed of sporting a hybrid Franken-brake-monster either as I always go with function over form. 

Aside from the lever, I'm assuming I'd need a new and compatible set of forks too. And the wheel, obvs. 

Plenty of pro teams aren't using disc brakes and they can get them for free.

If you're happy with rim brakes stick with them.

Avatar
fukawitribe replied to Libtardproud | 4 years ago
1 like
Libtardproud wrote:

Discs might be the ticket on gravel/grunge bikes, but way too heavy for road consideration

Modern road hydraulic systems add very little weight to the overall system, 2-300g was the last couple I looked at. Added price ? Yeah, sometimes quite significantly, but unless you're a pro or a hill climber I doubt that a decent hydraulic set-up will be noticeable over rim brakes. I'm not sure people's gating issue for/against hydraulics is based on weight considerations though..

Avatar
dave atkinson replied to fixit | 4 years ago
1 like

it might amaze you, but not everyone in the world has read it yet

Avatar
Mungecrundle replied to dave atkinson | 4 years ago
4 likes

Only this guy...

Image: 
Avatar
TheSmallRing | 6 years ago
0 likes

But why do disc brakes offer more control when braking?

I would have though due to the larger offset from the wheel centre, rim brakes would have a larger braking range for a given brake force.

Avatar
peted76 replied to TheSmallRing | 6 years ago
5 likes
TheSmallRing wrote:

But why do disc brakes offer more control when braking?

I would have though due to the larger offset from the wheel centre, rim brakes would have a larger braking range for a given brake force.

Simply they can use greater torque forces on a sheet of solid metal than hollow rims. I'd guess to get the same forces used with hydralic brakes at the rim, they'd have to build really solid heavy rims and that would be detrimental performance wise, to have that added weight at the furthest centrifugal point. Far easier to have the additional weight at the central point of a wheel.

Note there are always exceptions.. a cheap set of 'mechanical' brakes probably won't stop as well as a decent set of rim calipers. Hydralics is where it's at for more controlled braking.

Extra note, disc brakes aren't the holy grail for roadies.. if you don't need extra stopping power or modulation then you don't need discs. For anything off-road where stuff can get clogged or hamper performance in any way, discs are good, if you ride carbon wheels or are a particuarly heavy braker discs are probably good for you, if you mainly time trial, triathlon or hill climb, discs may not be useful.  Also discs are more expensive than rim calipers, rim calipers are more expensive than canti's.. and all of these mechanical advances are more expensive than getting new soles for your shoes, if that's how you'd prefer to apply the brakes.

 

Avatar
TheSmallRing replied to peted76 | 6 years ago
0 likes
peted76 wrote:
TheSmallRing wrote:

But why do disc brakes offer more control when braking?

I would have though due to the larger offset from the wheel centre, rim brakes would have a larger braking range for a given brake force.

Simply they can use greater torque forces on a sheet of solid metal than hollow rims. I'd guess to get the same forces used with hydralic brakes at the rim, they'd have to build really solid heavy rims and that would be detrimental performance wise, to have that added weight at the furthest centrifugal point. Far easier to have the additional weight at the central point of a wheel.

Note there are always exceptions.. a cheap set of 'mechanical' brakes probably won't stop as well as a decent set of rim calipers. Hydralics is where it's at for more controlled braking.

Extra note, disc brakes aren't the holy grail for roadies.. if you don't need extra stopping power or modulation then you don't need discs. For anything off-road where stuff can get clogged or hamper performance in any way, discs are good, if you ride carbon wheels or are a particuarly heavy braker discs are probably good for you, if you mainly time trial, triathlon or hill climb, discs may not be useful.  Also discs are more expensive than rim calipers, rim calipers are more expensive than canti's.. and all of these mechanical advances are more expensive than getting new soles for your shoes, if that's how you'd prefer to apply the brakes.

 

Thanks for your reply. I understand your point, but I don't think it's about the total amount of brake force. As is says in the above article, you can lock up rim brakes, so the max force you can apply is already enough.

If the goal is better braking range, I thought (from an engineering/physics perspective) that the larger offset from the wheel centre would give rim brakes the inherent advantage. 

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peted76 replied to TheSmallRing | 6 years ago
1 like
TheSmallRing wrote:
peted76 wrote:
TheSmallRing wrote:

But why do disc brakes offer more control when braking?

I would have though due to the larger offset from the wheel centre, rim brakes would have a larger braking range for a given brake force.

Simply they can use greater torque forces on a sheet of solid metal than hollow rims. I'd guess to get the same forces used with hydralic brakes at the rim, they'd have to build really solid heavy rims and that would be detrimental performance wise, to have that added weight at the furthest centrifugal point. Far easier to have the additional weight at the central point of a wheel.

Note there are always exceptions.. a cheap set of 'mechanical' brakes probably won't stop as well as a decent set of rim calipers. Hydralics is where it's at for more controlled braking.

Extra note, disc brakes aren't the holy grail for roadies.. if you don't need extra stopping power or modulation then you don't need discs. For anything off-road where stuff can get clogged or hamper performance in any way, discs are good, if you ride carbon wheels or are a particuarly heavy braker discs are probably good for you, if you mainly time trial, triathlon or hill climb, discs may not be useful.  Also discs are more expensive than rim calipers, rim calipers are more expensive than canti's.. and all of these mechanical advances are more expensive than getting new soles for your shoes, if that's how you'd prefer to apply the brakes.

 

Thanks for your reply. I understand your point, but I don't think it's about the total amount of brake force. As is says in the above article, you can lock up rim brakes, so the max force you can apply is already enough.

If the goal is better braking range, I thought (from an engineering/physics perspective) that the larger offset from the wheel centre would give rim brakes the inherent advantage. 

 

No you're right, it's about modulation (another reason caliper brake pads are towed in), and the 'force' I refer to is within the pistons which are pressured onto each side of the disc. As I understand it you need the additional force due to the central location of the disc. You'd certainly need less at the 'rim', but that would mean a more sturdy rim, which is not where you want additional weight on a rotating wheel. 

A real world advantage I can give you is that I can brake more confidently on discs with my hands on the hoods. Where as I have to be in the drops to get the same level of braking force on my other bike. Another is in wet riding decending a hill where in the dry on a rim caliper bike I have no issues, but in the wet I've had the odd hairy moment.... I think we've all had a few moments where you come accross an unexpected T junction at the bottom of decent in the wet etc.. 

 

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hawkinspeter replied to TheSmallRing | 6 years ago
2 likes
TheSmallRing wrote:

But why do disc brakes offer more control when braking?

I would have though due to the larger offset from the wheel centre, rim brakes would have a larger braking range for a given brake force.

My guess is that the disc pads are a lot more solid/rigid than the rubber pads, so there's a more linear relationship between applied force and the amount of friction (braking force) generated. Also, disc pads are set up parallel with the disc whereas rim brakes usually have a slight angle (toe-in) to prevent noise.

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TheSmallRing replied to hawkinspeter | 6 years ago
1 like
hawkinspeter wrote:
TheSmallRing wrote:

But why do disc brakes offer more control when braking?

I would have though due to the larger offset from the wheel centre, rim brakes would have a larger braking range for a given brake force.

My guess is that the disc pads are a lot more solid/rigid than the rubber pads, so there's a more linear relationship between applied force and the amount of friction (braking force) generated. Also, disc pads are set up parallel with the disc whereas rim brakes usually have a slight angle (toe-in) to prevent noise.

 

You could be onto something there

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kil0ran | 6 years ago
3 likes

Article needs updating to include the hybrid Yokozuna/Juin Tech R1 type brakes. In many ways better than the HY/RDs

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drosco | 6 years ago
6 likes

Commuting with hydraulic discs is so much better than rim brakes. Far better in the wet and I'm not getting through rims at an unhealthy rate. It's a no brainer.

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paulrattew | 6 years ago
2 likes

I love disc brakes (hydraulic) and wouldn't go back to rim brakes. For me its the reliability in all weathers and conditions - the brakes just always work and work consistently. It's also the modulation - no hauling on the brakes hard on a descent not being quite sure of when they will kick in, meaning that you brake harder than you may otherwise wish to provide a bit of a safety net. With discs, I can always give the exact amount of braking that I want without having to worry. 

The modulation really is a total eye openener if you've not used them before. Yes, disc brakes have a lot more power, but the positioning closer to the hubs means that the functional range of power you can apply is far greater (it takes far more braking force to lock up the wheels when the braking force is being applied closer to the hub - basic physics). 

I occassionally get a nasty squeal from the brakes, but not very often and given the vastly better performance it is not enough to put me off. My pads and rotors don't rub when I ride - most of this can be avoided if you properly space the pads when positioning the calipers to the rotors. 

Another major advantage is to do with the wheels. With rim brakes, fancy wheels are essentially a consumable. You will wear through them. With dics you don't have that worry or financial burden. 

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paulrattew | 6 years ago
1 like

I love disc brakes (hydraulic) and wouldn't go back to rim brakes. For me its the reliability in all weathers and conditions - the brakes just always work and work consistently. It's also the modulation - no hauling on the brakes hard on a descent not being quite sure of when they will kick in, meaning that you brake harder than you may otherwise wish to provide a bit of a safety net. With discs, I can always give the exact amount of braking that I want without having to worry. 

The modulation really is a total eye openener if you've not used them before. Yes, disc brakes have a lot more power, but the positioning closer to the hubs means that the functional range of power you can apply is far greater (it takes far more braking force to lock up the wheels when the braking force is being applied closer to the hub - basic physics). 

I occassionally get a nasty squeal from the brakes, but not very often and given the vastly better performance it is not enough to put me off. My pads and rotors don't rub when I ride - most of this can be avoided if you properly space the pads when positioning the calipers to the rotors. 

Another major advantage is to do with the wheels. With rim brakes, fancy wheels are essentially a consumable. You will wear through them. With dics you don't have that worry or financial burden. 

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sunnyape | 6 years ago
1 like

"No solutions for the screaming disk brake"

Give them a wipe with a bit of metho or hot water to remove the contaminant and prevent the squealing in the first place. Same as when you get crap your rim braked wheel.

"the cost of replacement when you contaminate the pads / disk"

Take the pads out, wash them with hot soapy water. Cost? about the same as rim brake pads.

"and just how many watts are lost by the rub..rub..rub of disk on pad when pushing on?"

If you've got pad / disc rub, then you've got an alignment issue, so align them properly in the first place. Same wattage lost when the wheel deflects and the rim rubs against the rim brake pad.

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Initialised | 8 years ago
0 likes

No rub on my RT99s, I used to get rub when climbing out of the saddle, not sure it's better wheels or centre lock discs that made the most difference. Apart from a biannual bleed and occasional pad change there's no maintenance with hydraulic braking.

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Augsburg | 8 years ago
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My advice from riding discs the past three years are:

  • Learn how adjust your brakes, true the rotors, and install  new pads - as disc brakes do require maintennace.  These are all easy tasks once mastered.  
  • Rotors of 160mm size are fine for those that weigh less than 150 lbs (75kg) - especially if you live in flat country.  For those of of us north of 220 lbs (100 kg), plan on a bike that can accept 180 mm rotors - especially if you ride hills.  The limiting factor is when you are riding in urban conditions and need to use one brake while signalling a turn with the other arm.  I learned early on that approaching an intersection on a downhill while only braking with my rear brake so I could signal, was too scary.  I also determiend the larger rotors are needed to maintain brake effectiveness on long downhill descents.  I've upgraded to 180 mm front and back.  The added benefit is larger rotors result in less brake pad wear, that is, pads last longer.  I cannot even image 140 mm rotors being safe for anyone but small children.  Swapping rotors to a larger size is a pretty easy, do-it-yourself job.  The hard part is buying the correct adapter to move the caliper to line up with the larger rotor - as most online descriptions of the necessary parts are terrible.  
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birzzles | 8 years ago
1 like

let me summarise:-

  1. SRAM are better than Shimano - better feel and hoods dont twist off
  2. Cable discs lose alot of the advantages, and are an extremely poor relation to the real thing.
  3. Wheels are alot heavier and there are not many decent aftermarket options under £500 (Hope and Hunt)
  4. Squealing discs have never affected me in 10 years of MTB, and on my new disc roadbike (Felt Z4)
  5. Discs add an immense amount to the retail price but big discounts are available end of season (my Z4 cost 1450)
  6. Discs are safer if you go anywhere near hills.
  7. Discs give braking that is more progressive and will actually stop you if required, you have much more control
  8. They are better in wet and in dry - hard to be progressive when applying rim brake death grip.
  9. They are zero maintenance - i have never needed to true anything, ever.  Replace pads occasionally, which is easier than rim brakes.

 

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muppetteer | 8 years ago
4 likes

I always shed a tear when I wash off all the black/dark grey brake grime from my bike when I ride it in the wet. The knowledge that its yet another layer of my rims is ultimately depressing. 

When Campagnolo sort out their disk range, I'll be first in the queue. 

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crazy-legs | 8 years ago
3 likes

The "more power" thing is a complete distraction - yes they are more powerful than rim brakes but they deliver that power in a far more consistent controllable way. I've never once unintentionally locked the wheels up on my disc-braked CX whether using it with road tyres or CX tyres. But it's only one factor in the argument.

Where disc brakes win is on the side issues that very few riders ever consider. Things like cable routing (with hydraulic hoses you can do whatever you want, run them internally, round corners), there's never any need to unwrap bars to replace cables, you simply bleed the brakes (maybe once a year at most), the levers maintain the same feel and travel no matter how much the pads wear, there's no braking gunk all over the rims, the wheels can be stronger/lighter/more aero cos they don't need a braking surface, they don't wear out because all your braking is done through a steel disc that is replaceable for a few 10's of ££ (rather than £1000 for your nice shiny carbon rims!) and they work even if you knock your wheel a bit out of true.

The quoted downsides:

more weight - really? You're worried about an extra 200g over an equivalent rim-braked bike? Once you've loaded your bike up with GPS, lights, saddle bag, 2 water bottles, top tube mounted feed bag, power cranks and all the other crap that I see hanging from the bikes of your average Sportive ride, you're really worried about an extra few grams?

less aero - again, really? See above - you've loaded your bike down with all that to set out for a 100 mile Sportive on public roads with things like junctions, traffic lights, shit road surfaces, lots of cars and you're worried that it may take you 8 seconds longer to cover that distance? OK then...  Rather than say, being able to stop half way down that bumpy descent in the rain... For a TT, yes, I see your point but for normal every day riding - Sportives, club runs, general riding it's irrelevant.

longer to change a wheel - You're not a pro. You'll be like 99.9% of riders who get a puncture; not waiting for a team car but sitting there at the side of the road for 10 minutes faffing, dropping your pump, losing the little valve cap, packing everything away again and then get back riding (at least, that's how I fix a puncture!) So the extra 4 seconds it takes to do up a thru-axle is irrelevant.

All of these arguments were done to death with MTBs about 10 years ago and I'd struggle to find any MTB rider wanting to go back to rim brakes! If you don't want them, don't buy them. Just accept that it's another choice that the consumer now has when buying a bike.

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Crashboy | 8 years ago
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For me as a fairly experienced "average" commuter/weekend rider, I didn't even fully understand the whole "modulation" concept until I had really tried discs in a variety of conditions and used bikes with/without them.  As the guy from Sram said in the article modulation "is not a term we particularly care for"  - can I suggest for the road.cc cycling glossary "white knuckle braking without skidding out of control" is a better termyes ?

After some experience I now get the idea - and I understand the concept of gradual, controlled braking without locking the wheel etc -  but I'm not sure how helpful it is for articles to keep going on about it as I am guessing other average punters like me won't really undertstand it, think about it or need to know it: all they want to know is the answer to a simple question: "True or False" - can I grab a handful of lever when someone lets their dog run in front of me on 20ft of extendable string (even though"it won't hurt you", and "it just wants to say hello") and stop safely, or will I go into an uncontrollable skid and fall off?".

Rider skill and willingness to adapt hasn't been mentioned much either: it takes ages to get used to a new bike / bit of kit / technique, and although there is a big financial element (really, that's the crunch,yes?) we all adapted to V brakes/ Cantis, from leather faced brakeblocks on proper metal wheels all the way to super stylee swisstops and carbon fibre etc (and posting on forums instead of sending in letters to magazines) without too much hassle. I used to love riding no handed and changing my old downtube shifter with my foot, but I didn't chain myself to the bike shed to protest when brifters came along, I just adapted my technique.  

Either way, as a total disc brake convert even I will go back to rim brakes if we are basically saying "Discs = less skidding",  because surely skidding is still one of the most fun things about riding a bike and still cool, no?

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