Wilfred Laurier

The main advantage of discs is the separation of two different duties your rim used to be responsible for. Rims are much more commonly damaged by impacts or spoke breakage, and this can make it necessary to disconnect or loosen your brakes, and effectively reduce their function, for your ride home. Disc brakes don't care how true your rims are - if the tire isn't hitting he frame or fork then you can keep riding.

Also, if you regularly ride with wet and/or dirty rims, rim brake pads will wear though the braking surface over time and possibly cause the rim to fail.

In terms of function, hydraulic discs are superior for stopping in wet conditions, and require less adjustment and maintenance. They are much much easier to set up than cantilever brakes, slightly easier to set up than V brakes, but only marginally easier to set up than caliper brakes.
Cable discs have an advantage in wet conditions, but are more difficult to set up than hydraulics, and require more maintenance.


In dry weather, to which many cyclists limit themselves, there is little functional advantage if your rims are in good shape.

Dave Mayer

I've spent much of my last two shifts at our local Co-op trying to solve disc brake problems. These included:

• A slightly bent rotor and intermittent rubbing. Very frustrating - hard to eyeball if the rotor was salvageable.
• The misery of removing rotor bolts that are frozen into the hub.
• Hydraulic pistons that are sticky. Will a bleed fix this? How many different types of bleed kits do we need to have in stock? And how many of the dozens of disc brake pad standards should we stock?
• The trial and error of trying to attach new calipers to a frame. We have a bucket of adaptors....
• Someone touched rotors with greasy hands. Cleaning up the rotors to acceptable performance ultimately took 2 hours of work, alternating between scrubbing with white gas and then sanding every square mm of the rotors with sheets of fine fresh sandpaper.

Anyway, hydraulic discs do not belong at a non-profit Co-op. When our (often low-income) clients are paying us $10 per hour for work on bikes, consuming much of an expensive bleed kit and $40 worth of pads represents a big loss to us.


I see a time in about 10-20 years from now when most mid-range and above bikes will be essentially unserviceable by Co-ops, due to the current proliferation of weird bottom bracket standards, suspension elements, and hydraulic discs. We will still be servicing 70's and 80's vintage bikes, but these basic commuter warrior bikes will be increasingly hard to find.

Steve B.

V brakes seem to have the spring tension change every time I release the brakes to get a wheel off the bike. I've futzed with V brakes a whole lot more than any others.

Leinster

So I need to buy new rims now for my wider tires? So pretty much a new wheelset. And a new free hub for my new 12 speed group set. Might as well buy a new bike. And all the new bikes on the market right now have disc brakes, soooo...

Steve B.

Even if my frame would accept a 32mm tire, I would have to play games such as remove air from tires, or set the cable tension nut so that I can back off tension in order to get the pads far enough apart to get the tire in. Rim size only slightly affects the width of the tire as I've discovered. This is on a Soma Smoothie with Ultegra dual pivots. Maybe newer model dual pivots or direct mount brakes allow the pads to open up more than a 10 year old version, ? don't know.

Are you saying that moving to a 23mm wide rim, vs. a 19, allows a 32 mm tire to magically clear the brake pads ?. I'm sceptical, but occasionally wrong.

MikeyMK

I find the progression better on discs, the power is there with initial bite, but regardless of comparisons between one bike and another they work in the wet.

I haven't experienced your alignment issues. I can fit new pads with no tools, I just use my padlock key to bend the retaining pin and push the pistons back. New pads fitted in one minute max. Old pads evenly worn, no adjustment required for the new ones. The caliper is either centre to the disc or it ain't.

tomato coupe

I don't know why this isn't mentioned more often. Rim design has more options if it isn't used for braking.

63rickert

Wide tires with rim brakes is only a problem when using brake calipers designed specifically for narrow tires. Which is a lot of the brake calipers out there. But not at all a characteristic of rim brakes. If you bought the kool-aid of narrow tires in the first place you get to do at least a complete re-fit and perhaps an entire new bike if you want to jump on bandwagon of wider tires. Such is fashion.

Unmentioned so far is disc brake forks must be stiffer. Tires become the only factor in comfort. The sort of road holding springy forks do is gone. Unless you want to go ahead and get a suspension fork. Basically 120 years of experience with frames is thrown out the window and start over.

Dave Mayer @ 27 is what I hear from mechanics. Most of them phrase it more colorfully. Only a few users imaginably "need" discs, we are all condemned to it. Slower users will never get a disc hot and never get the system broken in. Discs are no service to them.

Biggest problem with rim brakes is they are seldom set up effectively at all. Mafac brakes were introduced 1953. Design is still in production by at least three manufacturers. The new production versions are all expensive and very desirable. They work exactly as the originals. I have never seen a Mafac brake on an old bike that was better than marginal. When I am done adjusting them the owners have to be cautioned and are astounded how strong the brake is. "Why bother with discs?" is a common comment. Then there are the Campy Record OR cantilevers from early 90s which are still stronger and more predictable than many discs. No one is interested in developing rim brakes.

Most rim brakes were designed to accommodate wildly out of true rims. (Dual pivot brakes weren't and don't, that's another discussion.) Disc brakes just stop working if the disc is wobbly. Given that rims and wheels are dramatically straighter and stronger than in the heyday of rim brakes much could be done in way of using the rim as the disc. But that is theory, you can't get such a brake.

Leinster

Isn't that true of every bike tech ever? “My brakes don’t stop me”, well they’re not set up right. “My press-fit BB creaks” - you haven’t installed it right. “I keep getting flat tires” - your pressure is wrong. “My knee hurts” -your cleats are misaligned. “I’m switching to 1x” - your front derailleur is at the wrong height for your chainrings.

badger1

There, you see? Here we are, well into page 2. All it takes is persons of goodwill, willing to post 'points' that have been repeated ad nauseam on here in sundry threads, and 2 pages will quickly become 3, et seq.

63rickert

No argument from me.

AWillZ

I had definitely made up my mind and I wasn't looking for validation or to "stir the pot". I was interested to read what others thought and there was some good info that was added to the original post. The bike manufacturers will get rid of rim brakes sooner than later as it will allow them to streamline their offering and production process, but in my opinion, it's not a great technology advancement and it does make the bikes cost more and increases rolling weight. I am only speaking to road bikes.

Just as an aside, I spoke to three guys from the Aevolo Pro race team at the Cascade Cycling Classic this summer - they were all riding the new Cannondale aero frames, System Six, with discs on the last day, which was a hilly circuit. They (to a man) said that the bikes were great but none of them preferred the discs (alignment issues) and I don't think that frame comes any other way

smashndash

I can’t tell if you believe these things or if you’re pointing out the excuses people make to defend the things they believe in.

The performance difference between rim and disc brakes is disc’s ability to cut through water and stop in the wet. The “power” and “modulation” are better with hydraulic rim brakes. Most people haven’t even tried compressionless cable housing with their rim brakes. Hydraulic rim brakes are incredibly rare, but there have been a few and those are supposedly better than disc brakes. You could argue that disc brakes have an advantage because the pads sit closer to the rotor, but that causes a lot of rubbing issues. If rubbing were acceptable, you could do the same with rim brakes. Rim brake pads also compress a bit more but you can remedy that by using thinner or harder pads if it really bothers you.

I personally think that the main reason disc brakes came in was because carbon rim brake clinchers were really tough to get right, especially in the rain and long descents. That and maybe wider tires became fashionable and nobody wants 90s era V brakes on their road bike. More cynically, perhaps, bike manufacturers ran out of supposed “innovation” to push on us.

I truly sympathize with the co-op mechanic above. It must be tough, especially with so many people believing that disc brakes are the second coming. I know that, for most people, hydro discs are pain-free, but it also seems that there’s greater scope for things to go wrong. At the very least, it seems harder to get them “perfect”. On a group ride last week, two people had new Specialized disc brake bikes and both were rubbing HARD on steep kickers. Both of my friends on my team who upgraded to road disc last season rub on hill sprints. I’m not even OK with my bike making vague clicking sounds. If that happened to my bike (I sprint up hills frequently), I would demand a refund or warranty.

bobwysiwyg

Well, I just have to wonder why other machines of conveyance have switched from mechanical to hydraulic, and from shoe/drum to disc.

MikeyMK

Aaaaaand I think I'm done with this thread.

63rickert

I first saw disc brakes on a Japanese home market 3speed in 1973. Shimano. Next up was the Phil brake. Disc has been a long term project. Lots of engineering work has been done. Ten years ago the marketing push was huge while the brakes were still plain bad. Five years ago the true believers were proclaiming the second coming and the brakes were sometimes usable. In the meantime carbon rims and dual pivot rim brakes were causing havoc. The rim wear problem is far worse with dual pivot and the industry was not going backwards on that. Carbon rims were so easy to sell and hugely profitable.

Discs still have abundant problems, as you note in your post. Except if you believe the marketing, in which case they have gone beyond perfection. Engineering work and trial and error work continues to be done, and is done with a will. Basically nothing has been done with rim brakes. Unless you count Shimano Direct Mount, which is just digging a deeper hole. Even limiting the investigation to extant brakes it is evident that some rim brakes are much better than others at their ability to cut through water and stop in the wet. They are not all the same. No one is investigating why. Even very simple stuff like braze-on centerpulls is a miniature niche for the Jan Heine crowd. Peugeot did that for a couple seasons with the PY-10CP and any lucky enough to have ridden one knew how well it worked in the wet. But I'd be surprised if there were more than a couple hundred of those and it might have been less. Any lucky enough to ride Campy Record OR knew how well it worked in the wet and again there were likely only a few hundred sets. Half of which are still in the box with Campy collectors. Marketing trumps engineering every time.

Wilfred Laurier

The difference between disc brakes and rim brakes is not so much how the calipers work, but that the rim (which is in effect a very large disc brake rotor) goes straight though puddles and potholes, while a separate disc brake rotor at the hub is removed from debris and road hazards. There is no design of rim brake caliper or pad shape that will make up for this difference. Hydraulic rim brakes, which I had for a while in the late 90s, may have been a bit better than cable operated rim brakes, but the rim was still down in the mud and debris, so there was limited improvement possible.

Someone mentioned that the super tight clearance required for discs could be used to improve rim brakes, if the leverage ratios were changed, but the first pothole you hit would make your brakes rub a whole lot worse than discs do when you are sprinting up a hill.

I'm not sure what your point was about braze-on centre-pulls - these used to be called 'U Brakes' and were standard on MTBs in the late 80s/early 90s. They went away for a reason.

Also I think your timelines are off. In the late 90s and early 2000s, discs were in their infancy and there were some real dogs - Cannondale Coda discs come to mind as the worst of the lot, but the difficult setup and constant rubbing I saw on some other brands were also problematic. But decent quality hydraulic discs from ~2008 and onwards, IME, have been pretty much bolt-on-and-ride. I can see how a lightweight road-racing frame and fork with traditional QR axles could be problematic and less desirable than good calipers, but any modern bike that isn't flirting with the UCI weight limit could be made marginally better, at least, with thru-axles and discs.

indyfabz

Sorry. I was tied up all day yesterday and then too fried from the day to deal with computers.

Disc brakes are a fad and, therefore, unnecessary. They will go the way of the Pet Rock and all of the suckers who bought into them will feel embarrassed riding their bikes in public around serious cyclists.

Sapperc

I bought my 2016 Specialized Roubaix when the jury was still out on whether or not disc brakes were right for road bikes. Amount other issues, disc brake rotor scrub from too much flex in forks and rear triangles was prevalent in bikes then. Mine has 105 calipers and aluminum rims. Terrific bike. I’ve got well over 9,000 miles on it in 3 years so far.

I did one ride up and back down a mountain last year that was extremely challenging. I pretty much reached my limit to climb by the time I reached the top. After a break I headed back down. The road is very steep, narrow and heavily pitted and rutted with little or no useable shoulders in many places. The remote possibility of oncoming traffic around numerous blind turns means picking a path akin to a single-track decent. Brake fade became a serious issue almost immediately. I actually had to slow to a complete stop a couple of times to regain control. No doubt fatigue from the accent was a contributing issue as was the cold wind which caused my eyes to tear to the point that I couldn’t focus, but if I were to ride such roads more often hydraulic disc brakes would be welcome.

There’s another decent I ride more often where I would appreciate the ability to slow down quicker to negotiate several tight turns under control without having to scrub off decent speed so far in advance between turns.

If I ever buy another road bike I’d seriously consider the latest disc brake technologies and associated bike frame designs.

Happy cycling!

63rickert

I am not contending rim brakes work as well in the rain as best state of art discs in top condition. They don't. Good rim brakes are enough to do the job. Will absolutely require more effort from rider. Which is not a bad thing. Riding in the rain a rider should be on maximum alert to remain safe. Not many have ever been on brakes that good. Best rim brakes are way closer to average discs than is imagined. Industry was lazy for years and quit doing anything to improve rim brakes. When discs finally started to take off the decision was to ignore rim brakes entirely. Rim brakes could be much better for much less effort than has been dumped into discs. Most important would be getting the brakes to work out of the box. Quality assembly. And that would apply just as much to discs.

Almost every rider I know who has discs has problem after problem. A few go to the LBS weekly or more often for a year or more before finally getting tolerable function. The other way to handle the problem is to make that bike a garage ornament. Which is already the simple majority of bikes, discs have aggravated that. The exception to constant problems would be very new top end Shimano brakes. Those are getting easier to manage. Or at least often they are largely trouble free. You think it's been bolt on and ride for a decade. How many different systems of bolting on have there been in past decade? Do we have standardization yet? I can't see standardization from here. Nor have I heard that much reduction in constant rubbing.

Simple stuff like parking a bike on a rack is hard on discs. Discs are going on every new bike and they aren't ready. Any bike at all can be damaged parked on a rack, discs are just way more vulnerable.

I know what a U-brake is. Apparently you don't know what brazed CP is. OK, there aren't many of them, not surprising you wouldn't know.

Through axles have only been standard and automatic for what, two years. Also only about two years since sponsors bludgeoned the last CX pro with rim brakes into using beta discs. The CX pros who wanted to stay with rim brakes had reasons, good ones. They saw the majority of the competition on discs and didn't want to go there. It wasn't that they didn't want to win.

The big sales point for discs has always been powerful braking for trivial effort. Most riders don't ride much in rain, few wear out rims. It's the instant gratification that sells the brakes. Is it even a good idea to have that much instant brake? In a panic situation it might just be a good idea to have to work hard to brake. On a long descent discs mean forearms do not get so pumped, hands do not get so tired. Every other part of the body gets worked hard though. Should those with weak hands be encouraged to do long fast descents at all? I don't think so. Sounds more to me like a way for the unprepared to get in over their heads. I am way out of step for thinking it is not always a good idea to make riding easy. And then I see someone who has been trained to believe their brakes are perfect who just got instant and total brake fade.

And most of the discussion of all these points sounds like ad copy. Ad copy does not impress.

Atlas Shrugged

Disc brakes stop better.

indyfabz

A pump through the front spokes stops even better. What's your point?

DVC45

You use a pump to stop?!! You da man!!!

TiHabanero

In the past I was way overboard into audio equipment and discussions similar to this popped up all the time. In due time I figured out that none of it mattered as one man heard what he heard and another heard what he heard. Was there any real difference in what was really heard? Not to the average human being with average hearing.

Disc brakes vs. rim brakes is such a topic of discussion. For the average human with average needs and usage, disc brakes mean nothing other than increased cost. It is the industry driving the change as it keeps the product fresh, just like audio equipment. Let one man ride what he rides, and another man ride what he rides and both are satisfied.

Can it be that JP Penny was decades ahead of the bike geeks with their disc brake bike some 40 or 50 years ago?

OBoile

I'm amazed that people think it is a worthwhile use of their time to give long winded statements on this topic.