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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 they’re only now hitting the mainstream as big brands offer more 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 within the professional peloton, disc brakes are going to become an ever more familiar part of the road riding landscape.

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 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

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 clad rotor blade with a three-layer sandwich structure of stainless steel and aluminum. It says that this provides a better radiation performance that reduces the temperature while braking. 

SRAM 1x Germany 2015  - 2

SRAM 1x Germany 2015 - 2

Plus, with a disc brake 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 disc brakes, 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 disc brakes 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

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

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 disc brake 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 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 disc brakes, 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

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 2016’s hottest disc-equipped road bikes.

SRAM RED 22 HRD Brake (2).jpg

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 45mins 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 1-2sec 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

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

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. 

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

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

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 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

Pinarello Dogma Disc 01

Some disc brake road bikes use standard quick releases, like the Pinarello Dogma F8 Disc, while others 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

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?

Well, as our man Dave discovered when he visited a wind tunnel with Swiss Side, disc brakes, in their current incarnations, aren't particularly aerodynamically efficient.

Jean-Paul Ballard of Swiss Side told us, “We've measured a 16% increase in wheel drag between a disc-braked wheelset and a standard wheelset.

“We performed a direct back-to-back test of the Zipp 303FC in standard version and disc brake version, for our own competitor comparison purposes. That 16% is a constant offset in the performance curve across the entire cross wind angle range." 

The extra drag comes from three sources. The rotor itself adds drag, and because disc wheels need more spokes to cope with braking forces, there's more drag there too. On top of that, a disc hub is generally bigger than a standard hub and that increases drag as well.

Disc brakes could get more aerodynamically efficient over time, but probably not by a huge amount, and that’s one reason why they’re unlikely to take over completely from rim brakes, particularly when it comes to racing. Speaking of which…

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 is now permitting disc brake equipped road bikes in the peloton.

Bernie Eisel disc brake 1

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 the UCI has recently confirmed that disc brake trials will continue through 2016 too. If everything goes to plan, disc brakes will be permitted on a permanent basis from 2017.  There would have to be a massive change in momentum for this not to happen.

The extent to which teams and riders will use disc brakes on a regular basis is unclear. Will they become the default option or will they be used only for particular races/stages? Nobody knows for sure, but we can be pretty certain that disc brakes will become a familiar feature of top level road racing very soon. 

rotor uno being raced

Whether or not road racers are 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.

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

TRP Spyre SLC Mechanical Disc Brakes — £80.99

TRP Spyre Mechanical Disc BrakesBuy 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 a hydraulics.

Check out our review here.

TRP Hy/Rd mechanical interface hydraulic disc brakes — £94.99/brake

TRP HyRd disc brake - rear

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. 

Check out our review here.

Shimano 105 hydraulic discs — £299.95/pair

Shimano 105 hydraulic - callipers 2.jpg

Shimano 105 hydraulic - callipers 2.jpg

Shimano’s hydraulic disc technology has trickled down to mid-range 105 level. You get the front and rear shifters, disc callipers, pads, cables and hoses included in the £399 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. 

Read our review of the Shimano 105 disc brakes

Shimano BR-R785 road hydraulic discs — £399.99/pair

Shimano BR-R785 road hydraulic discs - rear disc

Shimano BR-R785 road hydraulic discs - rear disc

This is a very good first incarnation of road hydraulic braking from Shimano. 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. 

Check out our review here.

SRAM Rival 22 shifters/hydraulic disc brakes — £220.96/brake

SRAM Rival 22 Hydro groupset - disc brake on bike

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. 

Mat has worked for loads of bike magazines over the past 20 years, and been editor of 220 Triathlon and Cycling Plus. He's been road.cc technical editor for seven years, testing bikes, fettling the latest kit, and trying out the most up-to-the-minute clothing. We send him off around the world to get all the news from launches and shows too. 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 past winner of the Cycling Media Award for Specialist Online Writer.

41 comments

Avatar
rnick [129 posts] 1 year ago
3 likes

Interesting article..but a little light on realities of ownership.  No solutions for the screaming disk brake (surely contrary to the rules, particularly on a Sunday morning club run); the cost of replacement when you contaminate the pads / disk and just how many watts are lost by the rub..rub..rub of disk on pad when pushing on?

Avatar
Tony Farrelly [2893 posts] 1 year ago
5 likes

Well I've been running discs on my road bike for the last four years - first cable, now hydro. Haven't really noticed that much rub especially since I went over to hydraulic where the pads self centre  - certainly nothing to the extent of feeling like I'm being robbed of power.

If the rotors do rub it's the noise rather than any drop in power that's the irritating thing - normally that's caused by the disc warping or getting bent - you can bend them back - Park do a truing tool  http://www.chainreactioncycles.com/park-tool-rotor-truing-fork-dt2c/rp-p... and I think they do a fancier one as well. There are other makes also. None of them cost very much but you can get much the same result with some good pliers or an adjustable spanner.

We'll add something about maintenance to this - there's already a link through to our How to on bleeding SRAM brakes we'll be doing one on Shimano soon too. 

I bleed my own brakes - never had any problem with pad contamination, don't know anyone on the roadcc team who has either and the mountain bikers on the team are much longer term disc brake users than me.

Yes, on average pads costs more than rim brake pads but not that much more and they take a lot more wearing out than rim brake pads. 

Brake squeal? I don't care - let's people know you're there, I only really notice it in the sort of damp weather we've been having lately when the rotor's neither completely wet or completely dry, rim brakes tend to squeal in those conditions too.

The rules? Pfft!  3

I'd never go back to rim brakes 

Avatar
rnick [129 posts] 1 year ago
2 likes

There's the irony "not that much rub" - but we're happy to pay a fortune for the latest device to give us a few Watt's gain  1

I'll be looking at discs again in a few years..once the rims / spokes / hubs have been lightweighted and hydralic discs with manual l/r centralisation are available. 

Avatar
adam900710 [67 posts] 1 year ago
0 likes

I got a lot of  rotor rub on my old MTB, with 6 bolt rotor with QR.

The rub seems to come from bad rotor or bad 6 bolt wheels.

The roter seems to be flat but after installed on the wheels, it just rubs and the only method to fix is bending the rotor.

 

But after I installed RS685 set on my Fuji Sportif, and use center lock wheels and rotors,

never had any rub after initial adjustment.

The roter seems to be perfectly flat even I'm using a QR wheelset.

 

So I'm not worried about the rub.

 

But the RS785 caliper is not perfect, both front and rear caliper seems leaking in the RS685 set.

Changed them under warranty and it's perfect now.

Avatar
barbarus [434 posts] 1 year ago
2 likes

I also will not go back to rim brakes. Surely, if you are not buying your own wheels, it's better not be grinding your rims down every time you stop?

Avatar
matthewn5 [1006 posts] 1 year ago
1 like

The more I look at road discs, the more I think it's poor design, a solution in search of a problem. Stopping on a bike isn't mostly about the brake efficiency, its tyre to road adhesion that limits the back, and overturning momentum that limits the front. Try slamming both brakes on: you'll skid the back before going over the bars (as seen in sportives). It's much more important to ride defensively, so you're ready to brake in time.

1. Rim brakes are in effect a 622mm disc. Much better mechanical efficiency than a 140mm disc.

2. If they'd decided on a caliper in front of the axle there would be no need to invent a new axle standard, because the reaction to braking force would have pulled the axle into the dropouts. That seems a decision based on style, not technology.

3. Cables can be replaced easily and are largely recycleable, with a little bit of plastic/teflon waste. Waste disc brake fluid is a toxic pollutant. If it's anything like motor brake fluid, it's very corrosive too. You can't put that in your recycling bin.

I can see the benefit on a commuter bike, in the rain and sleet, but for those why not use hub brakes as in Holland or Germany? They go on for ever, never get contaminated, and don't need maintenance.

Sure, rims get ground down slowly, but if you use handbuilts they can be replaced, and the old ones recycled, to make new stuff.

Discuss.

 

Avatar
earth [344 posts] 1 year ago
1 like
matthewn5 wrote:

2. If they'd decided on a caliper in front of the axle there would be no need to invent a new axle standard, because the reaction to braking force would have pulled the axle into the dropouts. That seems a decision based on style, not technology.

That's a bit of priceless information and the kind of solution I like, just move the caliper.

I agree discs are a solution looking for a problem or perhaps a solution to the problem of getting more money out of us.

And the pads don't last nearly as long.

Avatar
joemmo [1164 posts] 1 year ago
0 likes

@matthewn5

1. They are also a disc that is about 25mm from the road surface and all the contaminants on it.
2. This is true. Nonetheless in 13 years of disc brake use with a front qr I have never, ever experienced a front wheel move in or pull out of the dropout.
3. Are cables really recycled in reality? In any case you can use cable disc brakes which are still very effective. As for the brake fluid, it takes about 25ml to fill a brake system. Yes, it has to go somewhere but then so does all the used grease and lube that you use on the rest of the bike. Shimano also use mineral oil, not dot fluid if that's a concern.

They're not a solution looking for a problem, for certain applications they're a better solution to an existing problem.

Avatar
Grizzerly [362 posts] 1 year ago
0 likes

If the component is called a rotor, why aren't they called rotor brakes? Surely,  if they are called disc brakes, then the active component must be a disc.  

Is this just a piece of added jargon to try to blind the gullible with science?

Avatar
joemmo [1164 posts] 1 year ago
4 likes
Grizzerly wrote:

If the component is called a rotor, why aren't they called rotor brakes? Surely,  if they are called disc brakes, then the active component must be a disc.  

Is this just a piece of added jargon to try to blind the gullible with science?

No, it's just to infuriate the pedantic.

Avatar
Grizzerly [362 posts] 1 year ago
0 likes
joemmo wrote:
Grizzerly wrote:

If the component is called a rotor, why aren't they called rotor brakes? Surely,  if they are called disc brakes, then the active component must be a disc.  

Is this just a piece of added jargon to try to blind the gullible with science?

No, it's just to infuriate the pedantic.

 

So, yes then.

Avatar
mike the bike [900 posts] 1 year ago
3 likes

I understand why some folk are reluctant to try disc brakes, nobody likes to see their view of the world turned upside down.  But, though I am an old man living on his pension, I gave them a try, first on my hybrid.  Wow, what a difference, better in every significant way.  Now two of my three bikes run discs and when I eventually replace my 'best' machine, it will too.

You can argue against discs, you can stick to what you know, you can produce all sorts of science to back you up.  And the best of luck to you, it's your bike and it's your life.  But you are missing out on a significant leap forward in bicycle design.  I don't know why or how, but that's the way it is.

Avatar
joules1975 [454 posts] 1 year ago
3 likes
earth wrote:

That's a bit of priceless information and the kind of solution I like, just move the caliper.

I agree discs are a solution looking for a problem or perhaps a solution to the problem of getting more money out of us.

And the pads don't last nearly as long.

I'm sorry ... disc pads don't last as long as rim pads? You've got that the wrong way round!!!!

I have ridden with discs on my MTB since around 1999 and have had discs on my utlility bike since around 2007, and my road bike for just over a year. So, from considerable experience I can say with confidance that disc pads last significantly longer than rim pads.

rnick wrote:

 the cost of replacement when you contaminate the pads / disk

Buy some disc brake cleaner (muc-off stuff is good) and you don't need to buy new pads when they are contaminated, you just clean them up.

matthewn5 wrote:

1. Rim brakes are in effect a 622mm disc. Much better mechanical efficiency than a 140mm disc.

Not really. 1. There is a limitation in the surface area used on rim brakes (yes they could make that area bigger, which would help). 2. In order to keep wheel weight down rims are carbon or alu, which are fairly soft, and so the pads have to be soft and the force being applied has to be limited in order to ensure bits don't wear too quickly and things don't bend (the rim brake surface can flex inward when brakes are applied, reducing the brakes effectiveness).

With discs, the rotors are steel, so wear isn't a problem, and the pads push against a flat bit of metal on either side, so no flexing of the braking surface. Much more force can be applied and pad material can be chosen to reduce wear and better handle heat.

i.e. the whole disc system is much more efficient as well as being more powerful.

matthewn5 wrote:

2. If they'd decided on a caliper in front of the axle there would be no need to invent a new axle standard, because the reaction to braking force would have pulled the axle into the dropouts. That seems a decision based on style, not technology.

That has actually been done. Among one or two others, Cotic stuck the caliper on the front right of the fork on their first generation Road Rat. They have switched back now, so guess it didn't catch on.

matthewn5 wrote:

3. Cables can be replaced easily and are largely recycleable, with a little bit of plastic/teflon waste. Waste disc brake fluid is a toxic pollutant. If it's anything like motor brake fluid, it's very corrosive too. You can't put that in your recycling bin.

Ah, but outer cables must be replaced fairly regularly - not as often as inner but still fairly regularly. I have never replaced a hydraulic hose except after a crash on my MTB.

Brakes only need bleeding maybe once a year at most (often less, unless you are doing alpine descents regularly), and shimano mineral oil is not caustic nor toxic (Avid/SRAM and some others do use Dot fluid like cars/motorbikes).

matthewn5 wrote:

I can see the benefit on a commuter bike, in the rain and sleet, but for those why not use hub brakes as in Holland or Germany? They go on for ever, never get contaminated, and don't need maintenance.

They have very little power compared to discs! The power of discs mean much metter modulation and much less effort to apply the brakes, meaning is easier for kids, people with smaller hands etc, and you can keep better control as you only need one or may two fingers to brake.

matthewn5 wrote:

Sure, rims get ground down slowly, but if you use handbuilts they can be replaced, and the old ones recycled, to make new stuff.

Rims wear out slowly? My neighbour has gone through four in that last three years. Yes he rides quite a bit, and is maybe a little nervous so is perhaps on the brakes more than he should be, and he rides in all but the worst rain/wind. However, if he had discs he would have saved about £250+ on pads and rims.

Avatar
andyp [1495 posts] 1 year ago
0 likes

'I see absolutely no need for discs ever on everyday road bikes'

 

I see a need, but then I own shares in companies who make these things. They are purely and simply a way to make more money for the manufacturers. You *really* need these new brakes. Oh, and a new bike to go with them. Oh, and new forks and wheels next time we change stuff around.

 

Through-axle. On a road bike. PMSL.

Avatar
iso2000 [72 posts] 1 year ago
1 like
matthewn5 wrote:

Stopping on a bike isn't mostly about the brake efficiency, its tyre to road adhesion that limits the back, and overturning momentum that limits the front.

I've read many comments from people saying that disc brakes won't give an advantage over rim brakes in dry conditions because the limiting factor for both types is locking up the wheels. However I have yet to see anyone quote any research on this. Does any exist to back up the claim or is it just bias?

I have a road bike with Shimano 105 rim brakes, OK they are not the best but it is disconcerting, to say the least, to feel how long they take to slow the bike down.  My next bike will definately have disc brakes.

Avatar
Grizzerly [362 posts] 1 year ago
1 like
iso2000 wrote:
matthewn5 wrote:

Stopping on a bike isn't mostly about the brake efficiency, its tyre to road adhesion that limits the back, and overturning momentum that limits the front.

I've read many comments from people saying that disc brakes won't give an advantage over rim brakes in dry conditions because the limiting factor for both types is locking up the wheels. However I have yet to see anyone quote any research on this. Does any exist to back up the claim or is it just bias?

I have a road bike with Shimano 105 rim brakes, OK they are not the best but it is disconcerting, to say the least, to feel how long they take to slow the bike down.  My next bike will definately have disc brakes.

 

I had a set of  105 brakes on my winter bike and found the same problem.   I replaced them with campag veloces, the improvement is amazing!  I ride at 105kg so my brakes have some work to do. 

Avatar
cyclisto [195 posts] 1 year ago
0 likes

Lets face it, disks are heavier, costlier, less hassle free and arguably uglier but they have better performace. I have V-brakes and I am not 100% happy but my next bike will definitely have disk brakes, mechanical or hydraulic.

Conversion at my existing bike is a thought but so far the hydraulic brifters price is simply ridiculously expensive as they cost as much as complete commuter bike, let alone that there are no options for my trusty 9-speed Sora groupset.

So go on, lets embrace disk brakes, and prices soon will fall

 

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barbarus [434 posts] 1 year ago
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+1 for disc pads wearing far more slowly than rim pads. If you only ride your bike in the dry then discs offer less of an advantage, sure.

And I have pulled a wheel out of the fork by putting the brake on but that's because I'm a muppet, not because disc brakes are bad.

As someone with a modest amount of money to spend on my bike I am much happier spending a reasonable amount of cash on wheels that I know should last well rather than considering my rims to be consumables.

If cycling was just about aesthetics then I'd ride a track bike but as it is, for me it's more like form follows function.

I don't really buy into this whole "they're only developing this stuff to take our money" narrative. Of course businesses try to make money but I honestly think that most companies are motivated to make that money by making bikes and cycling better. Most people in the bike industry actually love bikes!

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antigee [391 posts] 1 year ago
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ignoring the pro/against arguments an excellent, detailed well written article - thank you wink

 

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hampstead_bandit [614 posts] 1 year ago
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My last bike was a £2,600 carbon fibre road bike with Shimano Ultegra 11 speed / hydraulic discs, I rode this bike from November 2014 through to August 2015.

During this period I changed the rear brake pads twice, the front pads once. I ran a variety of tires including Conti's GP4000 II in the new 28c size, which was actually 31mm width when inflated.

With tires this large and sticky run at 80-85psi I never outbraked the tire, and most of my riding involves steep hills.  The braking performance was very impressive in terms of modulation and stopping power, especially in the wet. 

I come from years of mountain bike racing (downhill as well as cross country) and am very used to disc brakes. I tend to ride my road bikes very fast down hills as the road is wonderfully smooth compared to the off road trails I am used to (I also have a Specialized Stumpjumper 29'er)

I would have preferred through-axles on the road bike, as the front brake was noisy (rotor tinkle / swishing) when climbing or sprinting, and the rear wheel axle could shift under repeated heavy braking which caused a creaking under power, only cured by loosening the rear skewer, shimmying the wheel and tightening again. 

 

My current bike is a £1800 carbon fibre road bike with Shimano Ultegra 11 speed and caliper brakes. I've had this bike since August 2015.  

Apart from more limited braking in wet weather, I completely prefer my new bike. With the blue Swisstop brake pads the wet weather braking is not actually as bad as I remembered. 

Its much quieter to ride, lighter and accelerates faster. There is over 1 kg weight difference, with the wheels coming in 300 g lighter which makes a massive difference. 

 

For a commuting bike I'd go disc brake every time. For long distances in foul weather I'd go disc brake every time.  

When I've looked at performance disc brake bikes again, you need to spend decent money to get a light bike to really enjoy that fast road bike feeling, especially the wheelsets which are often 1800-2000 g even on bikes around £2,500 

 

 

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Mungecrundle [705 posts] 1 year ago
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Personally speaking I wouldn't go back to rim brakes.

It's not just the widely acknowledged superior braking performance and reliability in all conditions, but I really like my carbon wheels and there are few things more traumatic on a bike than descending in the wet, hauling on the brake levers to little discernable retardation accompanied by the sound of your expensive carbon specific pads disintegrating and road grit grinding paste scouring your beautiful carbon rims. Been there, done that, got the brown streaks on my chamois! Well actually I threw that one away.

I'll happily trade a few extra grams near the hub for a reduction in rim weight and the added advantage of being able to design the rim entirely for the purposes of keeping the tyre on and being aerodynamic. Tubular tyres make even more sense if you don't mind the glueing.

In my experience, it is as easy or easier to remove and replace wheels with a disc setup. Brake bleeding is a once a blue moon activity, as is changing pads, easily done by a home mechanic, it's a very simple and gratifying task. I don't suffer 'brake rub', my disc brakes do not squeal very often, only when dirty but they do give out a 'ting, ting, ting' noise for a few moments as they cool from a hard descent.

Technical proficiency with one's equipment and riding skills are important but disc brakes are genuinely easier to modulate and give better feedback which have to improve rider safety. I commute on my mtb most days and I'm just a club cyclist at weekends with my good road bike, I'm not a professional cyclist. However, I do know that I will outbrake pretty much anyone in the group I ride with in the dry and by a wide margin in the wet, two fingered and with a big grin on my face and without my forearms getting pumped. At least I did until the better riders also got disc brakes.

Aesthetically, I  prefer the disc to a caliper. In my opinion it's neater, the cabling can be more discreet and they look more technical which is complimentary to a modern carbon frame.

As to whether you 'need' them, well that's not really a very good question, do you really 'need' cotterless cranks? What is wrong with downtube shifters or toe clips? Aren't 7 gears enough? Solid rubber tyres have some advantages...I suspect that most of the remaining sour attitude to discs, and it really does come across as that, will disappear if and when Campag are able to offer a variant and when prices drop to make them available as standard equipment on sub £1000 bikes.

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joules1975 [454 posts] 1 year ago
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hampstead_bandit wrote:

 

When I've looked at performance disc brake bikes again, you need to spend decent money to get a light bike to really enjoy that fast road bike feeling, especially the wheelsets which are often 1800-2000 g even on bikes around £2,500 

 

 

Disc brake wheels definately have a way to go before we see the benefits that removing the brake track can have. Rim designers are currently still using fiarly standard rim designs, where maybe nothing more than a bit of smoothing has been done so that it appears the brake surace has gone.

Removing the brake surface will allow a bit more flexibility in terms of aero design, and should help lower rim weight.

Spoke and hub weight will increase a little, but the effect long term should be that the weight will move towards the centre of the wheel, and thus should get back to the current crop of lightweight wheels in terms of acceleration and handling (overall weight is likely to stay a little higher, but it's where this weight is on the wheel that affects performance - weight at the hub has very little affect when talking 100g here or there).

Until more R&D is done at the higher end, OEM dics wheels will remain fairly heavy because most cheap disc only rims out there at present are CX rims and it will take time for the higher end developments to trickle down.

There are however some very light disc wheels out there now - AM Classic Argent Discs for example (less than 1600g), and these use the same rim as the standard Argents.

The use of Discs in the pro races will have little effect on the racing, but it will speed up the development of lighter and more aero rims. Give is a couple of years and this will start finding it's way down to more sensible price points.

 

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bumble [21 posts] 1 year ago
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I've got (cable) disc brakes on my road bikes, have had for years. They're fantastic.

 

From my point of view, what's the advantage of rim brakes? none that i can see beyond perhaps a trivial weight saving.

 

 

 

 

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wycombewheeler [1073 posts] 1 year ago
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It's funny how there are two camps of people arguing against disc brakes, one saying there is no benefit it's all a con from the manufacturers, and one saying the difference so so pronounced it isn't safe to have discs and non discs in the pro peleton together.

which is it?

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hampstead_bandit [614 posts] 1 year ago
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@wycombewheeler

there is definitely a benefit for recreational riders in terms of being able to ride with more confidence in poor weather conditions, that is if you like/want to ride in poor weather conditions?

But for performance riding I'd like to see the "standards" settle down in terms of wheel axles (preferably a light weight through axle at either end) and for lighter weight disc wheels to be more affordable

If I look at the wheelset on my current caliper brake road bike, Shimano RS81 C24 for £315 coming in a smidgen over 1500gm; real nice feeling wheels which roll fast and are stiff under power

A quality disc wheelset from Giant for 2016 is their SLR 1 disc wheel system - 1650 gm for £850, and that is with a carbon fibre rim. 

Quite a large difference in "value" between a caliper brake and disc brake bike when shopping. 

 

 

 

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cqexbesd [87 posts] 1 year ago
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bumble wrote:

From my point of view, what's the advantage of rim brakes? none that i can see beyond perhaps a trivial weight saving.

 

Having got my first bike with disc brakes about 9 months ago (for touring and commuting) I'd say the advantages of rim brakes are less maintenance required. I know that seems to go against a lot of comments so maybe I am doing something wrong. Every few weeks at best - usually after having to do an hard brake to avoid cars/people/dogs on the bike path one of the rotors, usually the front, goes out of true and rubs on the pads. It's only very slight - I can't see it is out of true by eye but I can hear it and I bend it back and all is well for a few more weeks.

I've never had rim brakes that would do that. Obviously the wheel could go out of true but that was fairly uncommon once I bought decent rims.

I'm fearing it happening on a tour when I haven't got my disc truing tool with me.

My bike came with Shimano BR-M506 so not massively high end - maybe thats the problem.

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mattsccm [354 posts] 1 year ago
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Sadly so many of the above comments have little or no value.  Why?  Because its obvious that they have been written by someone who hasn't used discs on the road.  If thats you, how the hell do you know?  You don't.

Couple of errors as well.  A hydro system isn't any hassle to maintain.  I haven't done a thing to the disc brake system on my MTB except pads in the 7 years I have had it. Nothing. It doesn't need it.  I replace cables on other bikes much more often.   I guess this is one of those errors by those who haven't a clue.

Unlike some I must admit to having experience. I swappped my roughstuff bike to discs in 2010 and that soon became my road bike.  The recent weather has given me countless examples whereby discs work better than rims.  Can't say I saw anyone locking up a wheel yeaterday in the foul conditions except those on rims brakes whose braking needed lots of squeezing which then went from nothing to lock up.

Those who rant about complex systems are, I assume, still running a single speed system. I bet many of you embraced combined gear levers and brakes. You didn't need them so why?  

Just accept that times change. I'll be the first to  state that bikes looked at the best in the era just before integrated brakes and gear levers. Down tube shifters, hidden brake cable and not bloody black. However things change and when you try something you can make an informed and thus valid judgement.

I still refuse to see any virtue in black that isn't on the tyres.

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Chris James [438 posts] 1 year ago
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mattsccm wrote:

Sadly so many of the above comments have little or no value.  .....

Those who rant about complex systems are, I assume, still running a single speed system. I bet many of you embraced combined gear levers and brakes. You didn't need them so why?  

Just accept that times change. ..

 

I'm not sure that people are 'ranting'. In the case of multiple gears and STI levers I think the advantages were very clear.

With discs I think it is less clear cut, particularly for road bikes rather than cyclocross bikes. Dual pivots are a very effective braking system that are lighter, cheaper and more aerodynamic than discs.

Discs don't wear out rims, but then again my last wheels to give up the ghost were 9 years old, so I don't think it would be economic to change to discs just to avoid rim wear.

I'm agnostic really, but I might be more enthusiastic once a proper standard is in place re rotor size, and axle fittings.

 

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Crashboy [46 posts] 1 year ago
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Really interesting discussion: really interesting to see the huge range of responses to this based on looks, weight, engineering, and even - probably the most important thing?-performance.  

Maintenance issues: I had cable discs on my old MTB and did zero maintenance on them apart from a couple of pad changes in 5 odd years:  I didn't even change the cables!!  I crashed them, got them muddy/gritty/wet/hot/cold and abused them to death:  every now and then I squirted the rotor with degreaser, dried  it and  "wiped it" with a bit of fine emery paper ( from the puncture repair kit for roughing up the inner prior to putting the rubber glue on in fact!). Hydros on the current one (not particularly great ones by the reviews) are a class above in terms of performance, and once bedded in, I haven't had to do anything for two years as yet, apart from pads.

Compared to all the rim brakes I ever had - even given the record of abuse and negligence the bikes got over time - they were a game changer as I never had to worry about them not working very well.  In rubbish weather, nothing is going to work properly as everything is covered in water or filth or slime, but they do work better than rim brakes under these conditions in my experience.

Having said all of that, comparing discs on MTB's with Discs on road bikes is a bit unfair as you don't hit the same speeds on MTBs, (well, I don't   ), and phrases like "aerodynamics" and "weight penalty" don't really enter into it unless you are racing.  Or obsessed with pretending you are a racer.

Surely for commuters and the average person they are, therefore, a no brainer?

 

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Bez [608 posts] 1 year ago
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A couple of key benefits missing from the first section:

1. No rim wear.

2. No more black brake sludge! (One of my favourite reasons to use discs.)

There is endless discussion of why disc brakes aren't better or aren't needed or are some marketing gimmick, and 99.9% of it comes from people who haven't used them. Try them, and you'll find that all the your reservations are misplaced—unless, perhaps, you're the sort who only uses 23mm tyres and won't venture out unless it's shorts weather and the tarmac's bone dry.

The only thing I don't like about discs is that you can't use radial lacing  1

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