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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 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, disc brakes are 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’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 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

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 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’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

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 2018’s 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 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

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

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.

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.

Recommended disc brakes

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.

Shimano 105 R7020£172.99-£189.99/brake & lever

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 SLC Mechanical Disc Brakes — £59.99-£89.99

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 — £85-£109.99/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.

Check out our review here.

Shimano RS-505 hydraulic discs — £219/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 £399 (RRP) 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 RS-505 disc brakes

Shimano BR-R785 Di2 road hydraulic discs — £229.99/pair

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 — £235.06/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.

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Mat has 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. 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 winner of the Cycling Media Award for Specialist Online Writer. Now pushing 50, he's riding road and gravel bikes most days for fun and fitness rather than training for competitions.

65 comments

Avatar
Awavey [644 posts] 3 years ago
3 likes

for all the benefits of disc brakes, and they are considerable, maintenance and setup are key issues though as these spread down into more every day riders bikes, because Ive had friends with hydraulic brakes that had hellish problems trying to get them fixed when they went wrong, they seemed to just permanently leak, and it meant the bike was fundamentally unrideable as no-one is going to trust a brake system that might not be quite there when you need it.

and whilst the disk brakes on my road bike are cable operated (I was firmly put off the hassle of hydraulics) the margins between a free running disc and one that is slightly rubbing or modulating on braking because its slightly out of alignment, seems to be one of those measured in microns, maybe its fine if you dismantle your bike after every ride and clean every piece, before putting them back together, but outside of the obsessive and pro ranks most people dont do that or go on a how to setup brake discs course first to ride a bike.

for all their faults, rim brakes are dead simple to fix and maintain for the average rider, and thats a big plus in terms of usable bike technology IMO

Avatar
joules1975 [608 posts] 3 years ago
0 likes
wycombewheeler wrote:

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?

Very few are saying that it's unsafe to have both disc formats in a peleton. There are already huge differences in the way riders slow down anyway (just look what happened to G in the tour), whether due to braking ability/confidance or line choice.

Disc brakes in the pro scene won't make much difference to the racing at all, other than in the wet when those on discs will have more confidance than those on rims.

However, saying that discs will have little impact on the pro racing does not make them irrelevant, because as all those on here who have tried them are saying, for the average joe they are the far better option. We just need the wheel/rim manufacturers bring out some inovations so that the current downsides to discs begin to disappear.

Avatar
Crashboy [90 posts] 3 years ago
0 likes

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?

Avatar
wycombewheeler [1373 posts] 3 years ago
0 likes
Crashboy wrote:

 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.  

 

you can change gear on your brifter with your foot? can i see the video? can you also brake with the foot?:D

Avatar
joules1975 [608 posts] 3 years ago
1 like
cqexbesd wrote:
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.

 

The are like most cable discs in that only one pad moves when the brake is applied, and the disc is pushed across to the second pad. I have experience with loads of disc brakes and I've yet to come across a disc brake of similar design that hasn't presented some similar issue to the one you describe. The shimano ones are actually better than most, but still not great, although with the shimano ones it tends to be the rotor that presents the problem, and as with the calipers themsolves, rotors vary in quality. If you have one that's made of some form of cheese maskerading as steel, or one that wasn't made true, or wheel that has rotor mounts slightly out of alignment, or a frame where the mounts have not been aligned/faced correctly, then you have problems.

There is no doubt that disc brakes are more sensitive to manufacturing tolorances than rim brakes.

The TRP spyre brakes however are fantastic and have never presented me with any such issues (except when I tried fitting them to someones frame only to find the mount on the frame was not aligned correctly). They are as fit and forget as hydraulics, and it's all because both pads move, as per hydraulic brakes.

I suggest you switch your shimano brakes to Spyres or some Shimano hydraulics, and then you'll never want rim brakes again.

Avatar
Crashboy [90 posts] 3 years ago
2 likes
wycombewheeler wrote:
Crashboy wrote:

 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.  

 

you can change gear on your brifter with your foot? can i see the video? can you also brake with the foot?:D

 

With all the panache and bike handling skills I display, I might as well be doing so.smiley, but the problem is I've got Campag feet and Shimano brifters.  Incompatibility, you see...

Avatar
crazy-legs [1139 posts] 3 years ago
2 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.

Avatar
muppetteer [95 posts] 3 years ago
3 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. 

Avatar
birzzles [138 posts] 3 years ago
0 likes

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.

 

Avatar
Augsburg [31 posts] 3 years ago
0 likes

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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Initialised [337 posts] 3 years ago
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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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sunnyape [43 posts] 1 year ago
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"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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Simboid [142 posts] 1 year ago
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rnick wrote:

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?

A tiny amount of copper grease stops the squeal (just like on a car), pads aren't that expensive and can be cleaned if they're muddy, if they're rubbing loosen the mounting bolts and tighten with the brake on (3x repeated max will do it).

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700c [1267 posts] 1 year ago
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Simboid wrote:
rnick wrote:

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?

A tiny amount of copper grease stops the squeal (just like on a car), pads aren't that expensive and can be cleaned if they're muddy, if they're rubbing loosen the mounting bolts and tighten with the brake on (3x repeated max will do it).

Yet another maintenance requirement for the disc brake. My TRP rim brakes are pretty much fit and forget. They're effective, light, look good and compatible with the rest of my kit.

Discs may be great (but noisy!) for wet weather commuting, but using the bike purely for weekend & evening fitness and enjoyment as I do, the benefits just don't stack up.

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Simboid [142 posts] 1 year ago
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700c wrote:
Simboid wrote:
rnick wrote:

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?

A tiny amount of copper grease stops the squeal (just like on a car), pads aren't that expensive and can be cleaned if they're muddy, if they're rubbing loosen the mounting bolts and tighten with the brake on (3x repeated max will do it).

Yet another maintenance requirement for the disc brake. My TRP rim brakes are pretty much fit and forget. They're effective, light, look good and compatible with the rest of my kit. Discs may be great (but noisy!) for wet weather commuting, but using the bike purely for weekend & evening fitness and enjoyment as I do, the benefits just don't stack up.

Eh? A dab of grease in November will last through to spring and take 10 seconds, the pads are as easy to clean as rim brakes and last longer and re-centering the pads is far easier and faster than adjusting rim pads, more accurate and long lasting once done too. In any weather discs will stop in half the distance and with better modulation, in wet weather or on big descents you can go as fast as your tyres will let you. You can also commute as a proper part of the traffic and worry less about a car stopping faster than you, they are THAT good.

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paulrattew [306 posts] 1 year 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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paulrattew [306 posts] 1 year ago
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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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drosco [428 posts] 1 year ago
3 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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700c [1267 posts] 1 year ago
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Simboid wrote:

Eh? A dab of grease in November will last through to spring and take 10 seconds, the pads are as easy to clean as rim brakes and last longer and re-centering the pads is far easier and faster than adjusting rim pads, more accurate and long lasting once done too.

This thread is full of information about disc-specific maintenance (dealing with rubbing and bending back warped discs, bleeding the system, applying special grease ) . My point was that they have new maintenance requirements that I'd rather not have to deal with.

Simboid wrote:

In any weather discs will stop in half the distance and with better modulation,

Come off it! See https://www.youtube.com/watch?v=uHFSSXOSnxs 

Simboid wrote:

in wet weather or on big descents you can go as fast as your tyres will let you. You can also commute as a proper part of the traffic and worry less about a car stopping faster than you, they are THAT good.

I agree , as I've said - for wet weather and commuting they're probably ideal. And having used them on MTB's for many years they remain effective in the wet and muddy conditions.

This isn't the kind of riding I do on the road. 

Horses for courses, eh?

 

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kil0ran [1690 posts] 1 year 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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TheSmallRing [15 posts] 1 year ago
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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.

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peted76 [1576 posts] 1 year ago
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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.

 

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hawkinspeter [4079 posts] 1 year ago
1 like
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 [15 posts] 1 year ago
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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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TheSmallRing [15 posts] 1 year ago
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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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peted76 [1576 posts] 1 year ago
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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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Morat [344 posts] 1 year ago
5 likes

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

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Plasterer's Radio [551 posts] 1 year ago
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Spinning discs of death...remeber all that guff?

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pmurden [23 posts] 10 months ago
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They're a bit heavier. Perform way better in all conditions. Open up oportunities for better aero. Bosh

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slappop [80 posts] 9 months ago
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Quote:

...the aluminium being included because it transfers heat better than steel.

Silver would be even better since it has twice the thermal conductivity of aluminium, as well as appealing to the luxury end of the market.

I'm holding out for that.

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