Bike Forums - One Man’s View Of Disc Brakes

Bike Forums (https://www.bikeforums.net/forum.php)

- Road Cycling (https://www.bikeforums.net/road-cycling/)

- - One Man’s View Of Disc Brakes (https://www.bikeforums.net/road-cycling/1181550-one-mans-view-disc-brakes.html)

"You've ridden disc brakes, right?

"Yeah, yeah - totally."

https://media.giphy.com/media/xT9KVB...vYFG/giphy.gif

Quote:

[Disc brakes] generate much more stopping power, meaning there’s less force required at the lever to generate the same amount of deceleration as on a rim brake
An added bonus is that braking power can be quickly and easily boosted (or tempered, depending on your preferences) by changing rotor sizes.
Disc brakes offer better modulation than rim brakes, meaning it’s easier for the rider to precisely meter out exactly how much clamping power is generated. Peak stopping power occurs just before the point of lock-up and disc-equipped bikes are better equipped to flirt with that edge without crossing over. Disc brake power also tends to be more linear and predictable than on rim brakes, and it’s far more consistent in varying weather conditions, especially when compared with using rim brakes on carbon rims – a combination that yields notoriously poor performance in the wet and yet is also prone to overheating when dry.
Rim brakes still hold the upper hand in several key areas. Their biggest advantage is on the scale.
Disc brakes are also less aerodynamic than rim brakes – although the exact degree of that difference is still up for debate. *note that in the years since, the aero aspect has improved for disc, and in the 2019 article I'll link to later an argument is made they're more aero than rim.
The simplicity of cable-actuated rim brakes has plenty of upsides, too.

From a 2019 road.cc article which is relatively pro-rim (or maybe better classified as anti-disc): https://road.cc/content/feature/2562...ut-disc-brakes

Quote:

Levers, brake calipers, hoses, fluid and rotors weigh more than an equivalent rim brake setup. Manufacturers often try to minimise the difference but don't forget that disc brake hubs are heavier too, and disc brake wheels are often built up with more spokes of a wider gauge, although the lack of a brake track means that disc-specific rims are generally lighter. The thru axles that are used with many disc systems are heavier than quick release skewers. [note: personally I don't factor in thru-axle as a weight penalty, because having both a QR and TA road bike...I greatly prefer the TA regardless of what braking system may be on a bike]
Disc brake rub can be an issue. [I had it; but it took a 1-minute alignment procedure to fix]
Disc brakes affect aerodynamics. Some manufacturers have stated that the rim brake version of a particular bike is more aerodynamically efficient than the disc brake model, but it's not as simple as saying that rim brakes are always more aero. When Giant revealed its Propel Disc in 2017, for example, it said, "Engineers found that, with proper integration, a disc-brake design can actually improve aero performance compared to rim-brake configurations. “This is because the location of traditional calipers (either in front or behind the fork crown/ legs) creates 'dirty' air'. Opening up the fork crown area (by placing the disc-brake calipers down at the hub) means that the air hitting the new disc-brake caliper has already been disrupted by the leading edge of the tyre/wheel. This effect is further enhanced by an asymmetric fork that helps smooth out airflow over the caliper.”

Pretty balanced pro/con going to disc: https://www.bicyclenetwork.com.au/ti...vs-rim-brakes/

Quote:

Pro: Modulation / stopping power - The undeniable truth is that disc brakes allow you to stop over a shorter distance with more control.
Pro: Wet brake rims (especially carbon) and brake pads aren’t a great mix. Even with the best weather radar apps and planning, eventually you will be caught out in the rain. Hopefully its not when your heading down a hill. Yes, they probably will squeal but as long as they stop.
Pro: Inevitably rim brakes wear into the brake track on your rim, this reduces the stopping power and the life of the actual rim. Aluminum wheels are quite resilient but non the less they wear. Carbon rim wheels and the breaking heat generated wear down even quicker. Disc brakes remove all of that heat and friction wear from the rim and place it all on the disc rotor, a piece that can be easily replaced at a fraction of the cost of a complete wheel.
Pro: Caliper brakes are essentially limited somewhere in the 28mm tyre size realm. Disc brake equipped bikes don’t have this limitation, allowing frame manufacturers to design and produce bikes capable of fitting much greater tyre sizes. This can significantly increase traction/grip and also means added comfort from the increased volume
Con: Caliper brakes are essentially limited somewhere in the 28mm tyre size realm. Disc brake equipped bikes don’t have this limitation, allowing frame manufacturers to design and produce bikes capable of fitting much greater tyre sizes. This can significantly increase traction/grip and also means added comfort from the increased volume
Con: Whether you are replacing individual components, full groupsets or complete bikes, the disc brake version is almost always more expensive. Although there is likely there is likely to be less disparity as tech improves and disc brakes become more common.
Con: When comparing the different frame and fork construction methods, the weight difference can be anywhere between 300g to 500g. Though disc technology is advancing rapidly, it is still slightly heavier when looking at the complete system.
Con: For years there has been a perceived risks of the rotor being dangerous in a crash. This was possibly true on the original styles of rotors, but technology is moving fast and edges are now much more smooth and rounded – as shown in this short video.

Modulation, as discussed in this article: https://www.bikeradar.com/features/h...ke-modulation/

Quote:

I’m not at all going to argue with the notion that rim brakes and conventional braided cables have worked for ages. They’re also often very light, easy to service, and highly tuneable. But just because something has always worked doesn’t mean it’s the best way to do things. After all, there’s a reason we don’t use lead paint, asbestos, nailed-on cleats, or rotary phones anymore, either.
Taken from an outsider’s perspective, squeezing a couple of chunks of rubber (or cork) against a rim is flat-out silly, particularly when you consider the exorbitant prices often attached to high-end bikes these days. Likewise, even the best rim brake calipers can be prone to flex with their relatively long expanses of material and multiple pivots.
“The braking surfaces are more consistent and the friction material is a lot more sophisticated,” says Kantor. “I think the people that make rubber pads for a living would argue that they put a ton of work into it and I’d agree, but we’re able to achieve a more complex relationship with a disc brake pad.”
Hydraulic lines take away much of the signal loss that occurs in mechanically actuated brakes due to line friction and housing compression plus they offer a greater mechanical advantage that reduces hand effort. “Any time you’re using less hand effort, you’re less likely to spike that lever. If you have to pull really hard to get a desired stopping force, you’re not able to control your hand effort as well.”

Quote:

Originally Posted by on the path (Post 21104673)

Um, I'll declare that rim brakes categorically are just as good as disc brakes. And disc brakes are good enough. And heavy. And expensive. And overly complicated for the application.

I realize that this is the 41, but how can a thread like this contain no meaningful mention of tires? Tires are the single most significant component of any vehicle braking system. Ever hear - "your car is only as good as its tires"? When you're done "modulating" it's all up to the tires.

Funny you should mention the importance of tires. From the 2016 bikeradar article:

Quote:

Without having to worry about accommodating a caliper, disc-equipped road bikes can now more easily fit higher-volume tires and wider rims for improved traction on a more diverse mix of terrain. Since the seatstays no longer have to be reinforced to accommodate a rim brake, they can be made more flexible.

So yeah, tires are important, and disc brakes allow you to put the very best tires and rims to suit your braking needs. Also not to be lost in the benefits: comfort

So everything we've been discussing has been borne out in those various links. You know what they all agree on? That disc brakes have better stopping power and modulation. You're the only one claiming rim are equal to disc brakes in braking performance.

Quote:

Originally Posted by CarloM (Post 21104856)

Warning: wall of text to follow, primarily aimed at "on the path" as it mostly just confirms everything we've discussed as pros and cons of disc and rim brakes. Most don't need to read.

So @on the path yeah we all know "anyone can say anything". But let's see what some folks have to say on cycling sites where they have a reputation at stake, vs. Anonymous Keyboard Warriors like us. Yeah I know, the best part about Conspiracy Theories is that they can't be disproven. Any contrary evidence is just dismissed as "part of the conspiracy". So if that's your stance, you can stop reading here.

2016 article: https://www.bikeradar.com/features/r...-need-to-know/
Remember this is in the early days of disc on road bikes, so many improvements have happened since this article was written, but even so here are some key points from it...

From a 2019 road.cc article which is relatively pro-rim (or maybe better classified as anti-disc): https://road.cc/content/feature/2562...ut-disc-brakes

Pretty balanced pro/con going to disc: https://www.bicyclenetwork.com.au/ti...vs-rim-brakes/

Modulation, as discussed in this article: https://www.bikeradar.com/features/h...ke-modulation/

Funny you should mention the importance of tires. From the 2016 bikeradar article:

So yeah, tires are important, and disc brakes allow you to put the very best tires and rims to suit your braking needs. Also not to be lost in the benefits: comfort

So everything we've been discussing has been borne out in those various links. You know what they all agree on? That disc brakes have better stopping power and modulation. You're the only one claiming rim are equal to disc brakes in braking performance.

So now we're down to 'everybody says so' as our validation and proof? This is perfect for the 41!! How about independent testing? I'll take a look at results from a rigorous, thorough independent test. The rest is just nonsense.

And you totally missed the point about tires. It's not about size or comfort. It's about grip. And it's the same with bicycles. The grip of the tires' contact patch has a lot more to do with stopping power than any type of braking system.

And please, spare us the term "modulation." That's just parroting industry speak and a go to response from someone who really doesn't understand what he's talking about. Have a great night!

I look forward to your provision of independent testing. Until then you're doing the adult equivalent of a child plugging their ears with their fingers and yelling "nananananana" while namecalling because you are hearing things you don't want to hear.

Quote:

Originally Posted by on the path (Post 21104673)

Um, I'll declare that rim brakes categorically are just as good as disc brakes. And disc brakes are good enough. And heavy. And expensive. And overly complicated for the application..

Overly complicated?

Maybe for simpletons

.

Quote:

Originally Posted by on the path (Post 21104897)

Why the trolling?

Quote:

Originally Posted by Seattle Forrest (Post 21104981)

Why the trolling?

I'm sorry to disappoint you, but it looks like the trolling is coming hard from both sides. Each side frothing at the mouth waiting to throw down. Time to call in the riot police before the demonstration becomes violent. Close it down. Now.

Quote:

Originally Posted by seypat (Post 21105036)

Time to call in the riot police before the demonstration becomes violent. Close it down. Now.

Noooooooo!

If it's locked down we'll never get to see it pop up as a zombie thread.

If you don't like the thread, stay out of it. No one is making you follow it.

Quote:

Originally Posted by noodle soup (Post 21105041)

If it's locked down we'll never get to see it pop up as a zombie thread.

Not only will it come back as a zombie thread, someone will ask "what's a rim brake?" when it does.

Quote:

Originally Posted by noodle soup (Post 21105041)

Noooooooo!

If it's locked down we'll never get to see it pop up as a zombie thread.

If you don't like the thread, stay out of it. No one is making you follow it.

Well, if you are going to accuse someone of trolling, you need to quit doing it yourself.

Quote:

Originally Posted by tomato coupe (Post 21105083)

Not only will it come back as a zombie thread, someone will ask "what's a rim brake?" when it does.

:roflmao2:

:thumb:

Quote:

Originally Posted by seypat (Post 21105036)

Ok, but most of it is a lot more skilled than just saying "up is down" over and over again.

Quote:

Originally Posted by on the path (Post 21104600)

I'm sure it happens but I've not heard of anyone wearing out a brake track on a rim.

I was with BF member RoadFix when the brake track blew off his front rim in the mountains. It was worn very thin. I have seen that on at least 2 other occasions, rim failure due to wear on road bikes.
When I used to live in the mountains I used a mountain bike with rim brakes a lot due to the weather. I could tell when the rim was gone because it would get a low spot near the seam and make a bad thump every time the pads squeezed it.

I did a century in a rainstorm in the mountains with lots of descending. The road grit turned the aluminum of the rim into a thick, black slurry which was flung all over everything. Not to mention I had to ride the brakes if I wanted to have any braking at all.

Quote:

Originally Posted by seypat (Post 21105096)

Well, if you are going to accuse someone of trolling, you need to quit doing it yourself.

where is this accusation of trolling?

Quote:

Originally Posted by on the path (Post 21104897)

And please, spare us the term "modulation." That's just parroting industry speak and a go to response from someone who really doesn't understand what he's talking about. Have a great night!

Modulation refers to the ability to control the power of the brake, the ease of control. Some brakes can be called "grabby" or "like a light switch". Those brakes don't have good modulation. When I bomb a descent on my mtb, I have confidence the brakes are going to be consistent and not lock up unexpectedly or lack the power I ask of them. That's good modulation.
Rim brakes I have used go from pretty good to absolute crap. Being over 200 pounds I sometimes wish for more power on steep descents. Have not tried road discs yet but I'd like to.

Quote:

Originally Posted by noodle soup (Post 21105133)

where is this accusation of trolling?

You're much more polite than I am.

Quote:

Originally Posted by on the path (Post 21104897)

So what disc brake bikes have you ridden and how much?

Ppl say discs are not affected by rain. Thats a lie. They are. Less brake power and a lot of noise.

Quote:

Originally Posted by Racing Dan (Post 21105232)

Ppl say discs are not affected by rain. Thats a lie. They are. Less brake power and a lot of noise.

Noise? Sure, sometimes. Reduced braking power? Not that I've noticed; I one-finger brake downhill in the rain - no issues.

Quote:

Originally Posted by WhyFi (Post 21105482)

Noise? Sure, sometimes. Reduced braking power? Not that I've noticed; I one-finger brake downhill in the rain - no issues.

I've noticed some loss of braking power in the rain, but nothing like rim brakes on CF wheels.

Quote:

Originally Posted by big john (Post 21105124)

You brought back memories regarding the aluminium slurry created when riding hills in the rain. Had to be the most difficult thing ever to clean up. I still have stains from that stuff around including my garage when I decided to rinse my bike post-ride once.

Quote:

Originally Posted by WhyFi (Post 21105482)

Noise? Sure, sometimes. Reduced braking power? Not that I've noticed; I one-finger brake downhill in the rain - no issues.

Mine squeal like a pig and looses 1/2 the brake power whenever its wet out. Roller brakes are much less affected by rain.

I make similar adjustments when riding my bike in the rain as I do when driving in the rain. It rains enough around here that many riders own rain bikes. Wet roads effect braking, No matter the system. We have ‘New Locals’ bouncing off the Jersey Barriers all the time late fall when the rainy season starts.

Quote:

Originally Posted by colnago62 (Post 21110279)

We have ‘New Locals’ bouncing off the Jersey Barriers all the time late fall when the rainy season starts.

I probably laughed harder at the term "New Locals" than I should have.

Living in SoCal, I do not know about this "rain" of which you all speak. But I would hazard a guess that even the best disc brakes aren't completely unaffected by rain. Just less affected than comparable rim brakes.

Anyone who thinks they can ride (or drive, or heck, even run) at the exact same high speed and carefree manner as they do in dry weather is in for severe disappointment...and injury. Everything is impacted by rain: cars, bikes, shoes, etc. The better technologies minimize/reduce the effect, but nothing is going to perform identically in rain as it does in dry weather. Sheer physics. Even if your brake miraculously could be unaffected by rain, your tires won't be, and new rains always bring up road oils that make pavement slick.