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Today April 2019

I'll go rim brakes. Mainly because of cost. But I also like the simplicity and the elegance of them for my first proper bike.

To me the difference is mostly about riding in the rain. On dry tarmac, well maintained disc and rim brakes will stop equally well. On a wet road it's no contest, discs win hands down. The higher pressure of the piston against the rotor necessitated by the small rotor vs. rim brake surface diameter pushes water out of the way easily, whereas the pads on a rim brake may need a full rotation to wipe the rims dry enough for action. It could be the difference between crashing into the guy in front of you or being safe.

A second difference is that all rim brakes are wire operated whereas disc brakes give you a choice of wire or hydraulic operation. Hydraulic brakes take much less effort, which can make a huge difference on a long descent in wet and cold conditions (Norikura anyone?). A major reason why hydraulic brakes need less lever force is that any wire needs a spring at the other end to pull the wire back when you release the brake: Wires work much better for pulling than pushing, so the wire will be pulled both ways. That's why when you apply the brakes, your hands not only provide the pressure that squeezes the pads against the brake track but also the force that compresses the return spring. Hydraulic fluid doesn't need any return springs, it flows as easily one way as the other.

With disc brakes you can use really light weight carbon rims, without the risk of overheating carbon clincher rims on long & steep descents.

With rim brakes, your rims will wear out. After several 10,000s of km you will need new wheels or at least have the wheels rebuilt with the old hubs and new rims. With disc brakes, well built wheels should last forever, unless you have major accidents!

If you break a spoke on a disc brake wheel, the rim may start wobbling, but the brakes will still work. On a rim brake it's a major problem.

The above factors favour disc brakes.

OTOH, it's much easier to see how worn a rim brake pad is, compared to a disc brake pad which is much slimmer and sits inside the brake caliper. It's also much easier to change them. You'll probably spend less money on rim brake pads than on disc brake pads and rotors over a given period of time. If you have trouble seeing how many fractions of a mm of pad wear you've got left on your disc brake, next thing you know your brake may not be working at all while you're trying to descend some mountain. If your eyesight is too poor to figure out when the pad is nearly gone, it may be safest to replace pads by how many 1000 km or months you've been riding since the last change.

Most cable operated disc brakes need regular adjustments, far more so than rim brakes. Hydraulic disc brakes don't. They just keep on working well, ride after ride, until they don't (when the pads are worn out). With cable operated disc brakes, get used to learning to use your hex keys to do the adjustments after some wear.

If you even slightly bend a rotor, say when you've been leaning the bike against something, you'll get brake rub. It can be tricky to get rid of again.

Disc brakes can get noisy, especially when oil from the chain contaminates the rotor in the rain.

Rim brakes have a slight weight advantage, but weight on bikes is overrated anyway, compared to weight of riders :)

Reinstalling a wheel, say after you fixed a puncture, is slightly more complex with disc brakes as the rotor needs to slide back into the caliper. With hydraulic disc brakes you must never push the brake levers with the wheel removed and no spacer inserted into the empty caliper (Shimano provides plastic spacers).


For me personally, the benefits of disc brakes while riding in the rain outweigh everything else. I'm very happy with my Shimano hydraulic brakes. I do not skip chances to ride just because I can't guarantee 100% that it will stay dry. When I sign up for a brevet, it could be months before the ride, when I have no idea what the weather will be like on the day. On a 20, 27 or 40 hour ride the weather can always change. I've done a 300 km brevet where it was raining for the first 150 km.

Both of my bikes now use disc brakes, but other people have different priorities.
 
Pretty good summary of good/bad points of discs and rim brakes.

One more negative about rim brakes is that it is getting harder and harder to find rim brake bikes and wheels. I still prefer rim brakes since they are less fiddly and quieter and since I don't tend to be in the mountains when it is raining. The Shimano XTR brake's design gives me enough power for stopping on a steep downhill in the rain when caught out on my commute. But that's me. And, that said, looks like the market is not going to give me many options if I want to stay with rim brakes.
 
@joewein @Karl I recently read that the Katusha pro team are only running disc brakes on their Canyon bikes this year (the first team to switch). Not that people should base their decision on that but interesting nonetheless.

The CAAD12 105 is 19 man and the disc version is 23. They apparently weigh the same - the finishing kit is also identical AFAIK. Food for thought.
 
How wide of a tire does the CAAD12 accept? 28s? I like that bike a lot. Been looking at the CAADx as well.
 
Only concern I had with the CAAD 12 or CAADx is that they use a press fit BB. Never had one, but read a lot about them being creaky. I much prefer the threaded BBs. Easy to replace and quieter.
 
@Karl ah, now I understand why I saw a vid pop up on YouTube about a creaky bb and a CAAD. I'll have a look. I also know nothing about bbs generally so I should read up on those.
 
The CAAD12 105 is 19 man and the disc version is 23. They apparently weigh the same - the finishing kit is also identical AFAIK. Food for thought.
Personally, I have been riding hydraulic disc brakes on bikes since ~2005 — no way I am going back to rim brakes. The whole road bike industry is going to be disc brake-only for the majority of the market very soon — within the life time of your next bike's frame. Many framesets released since last year are disc brake-only already. Getting the disc brake version is going to be more future proof. I would forgo mechanical disc brakes, that's a weird half-step that will make upgrading to a fully hydraulic setup a very expensive proposition (as you'd have to change the shift/brake levers as well).

@joewein has summarized the pros and cons very well. There is one thing I would like to add, and that is friction: hydraulic brakes are unaffected by brake line routing whereas brake cables are not. You always have the same much lower friction. Moreover, you also get much better feedback at what your brakes are doing, because the fluid in the brakes behaves the same in both the push and pull direction. Even hydraulic rim brakes (which my mom has on her cross bike) are miles better than cable-operated rim brakes for that reason.

A lot of the arguments by conservative roadies bring up non-issues as arguments, e. g. supposed reliability problems or the fact that they'd have to learn new maintenance procedures. Don't listen to that. Brakes, no matter the type, are supremely reliable. I have literally ridden tens of thousands of kilometers on disc brakes without a single failure (outside of maintenance — all parts have a finite life time). And the only unexpected failures I have heard of amongst people I know were accident-related (e. g. bent rotors due to a tree branch that got caught up in them).

The CAAD12 is a cracking bike that you can upgrade over the years to a very competitive machine in terms of weight and performance. Moreover, it is widely available in Japan. In case you are interested in wider tires, have a look at the CAADX, too. IMHO 28 mm should be the norm for most road riders these days (another plus for disc brakes, they place no restriction on tire size).
 
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@Karl ah, now I understand why I saw a vid pop up on YouTube about a creaky bb and a CAAD. I'll have a look. I also know nothing about bbs generally so I should read up on those.

FWIW, been browsing a lot of bikes and the selection of rim brake bikes is dwindling fast. Same for wheels. Hunt only makes 1 or 2 rim brake wheels but offers plenty of disc wheels. So, as @OreoCookie says, looks like the market is quickly moving to the world of disc brakes and isn't going to offer many rim brake options. :cry:
 
@Karl
I am not sad to see rim brakes go. There are only very few specialized circumstances where rim brakes offer a tangible advantage — and these usually involve very specialized applications. The only evident advantage rim brakes have is that they are currently cheaper. But given that even entry-level mountain bikes come with hydraulic disc brakes these days, this is just a matter of time.

Note that some limitations are due to UCI rules that forbids shrouds and covers for disc brakes, but allows to tuck away rim brakes into aerodynamically more convenient locations. Moreover, unless the UCI changes their minimum weight requirements, it is perfectly possible to build a 6.8 kg disc brake bike — it is just out of (financial) reach for most of us.
 
Yes, I have noticed that the choice of rim brake rims and wheels is already shrinking.

About a year ago I had custom entry level wheels (yeah, I know it sounds like an oxymoron!:D) built to my specification by Tim at GS Astuto for my son's Araya Federal. The original ETRTO 590 (26 x 1 3/8") rims had got bent out of shape by Italian airline baggage handlers. New 650B / 27.5" rims were close enough in size to work with the existing rim brakes and would give me more tire choice.

I wanted these new wheels to be usable for both the Araya, which uses cantilever rim brakes and as potential spare parts for my Elephant NFE, which uses disc brakes. So I went for a center lock hub and aluminium rims with a brake track but realized how few rims in that size are still available. For 700C it probably still looks a bit better, but I think the the writing is on the wall.

I expect there will always be rim brake bikes and parts that work with them, such as replacement rims, calipers, brake shoes, etc. simply because of the legacy installed base and the customers who are reluctant to change. Three decades after Shimano launched the first brifters for road bikes you can still buy down tube shifters and separate brake levers as well as entire new bikes configured that way.
 
It also makes a difference whether you are looking in the vintage parts bin (next to the quill stems and friction shifters) or whether you have a healthy set of new options. I noticed this with MTBs: I bought the last generation of 26" mountain bikes, and it shows: my tire choice is very small, and if something breaks, I will have to look at the used parts market.
 
What is that?
This is the latest generation Fargo.
They 2 two tweaks on it that really has my attention
- they lengthened the reach by 1cm on the Large. (on my old Fargo, I fall right in the middle between a L & XL, this tweak solves it)
- the new Fargo can handle 27+, 29, 29+ wheels. (I own all three, so it would be fun to sort it to my liking).
 
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