It would have been less controversial in here to ask if it’s better to be a Democrat or Republican. There are spicy threads on this topic already.

Figured I'd ask because of late search application here doesn't always bring up all the posts. Plus, trying to follow the 'bouncing ball' over time and the timeline of the iterations of changes in the equipment (if any) has proven challenging. I posed a variety of questions to understand more if this is all hype, and have past problems been dealt with, what are the benefits, and what does the future look like with brakes on Tri bikes. If that is controversial to some, oh well... I have always been in the camp that 'we don't need it' and 'I don't want it'. But, I am happy to be proven wrong. And, I would like to understand that whether I am right or wrong, what the future holds... So, for you fortune tellers out there, I am willing to listen.

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Running is the best source of fiber that I know of...

At this point, if you want to buy a rim brake triathlon bike, you're starting to look at either used or old-new-stock from 2020/2021. There are a few rim brake options, but they're largely older models and most (every?) manufacture also has a disc brake option as well. It's also getting pushed at the component level (Shimano 12 speed Di2 Ultegra is only semi-wireless for disc brakes). Is it better? Not sure, but it does make for some great deals on rim brake equipment (e.g., disk wheels). My road bike has discs, but my tri bike is pretty far down on the upgrade to discs list (more likely to snag some 11 speed Di2 as that becomes cheaper).

My .02 on all things bike controversial:

Disc brake are here to stay. Biggest negative is learning how hydro works from a maintenance/ travel perspective. Your options become limited and will continue to dwindle.

Tubeless tires of the width suggested by your rim manufacturer as the most aero; is probably the most optimized set up aerodynamically. From a rolling resistance perspective, pick a fast tire with the amount of flat protection that you are comfortable with.

Frameset: see the peak aero article from a couple of years ago. There are a lot of fast frames the question is which one can seat you in an aerodynamic and biomechanicaly powerful position.

You still need to get a bike fit; now that applies to aero and biomechanics.

One aspect in what you mentioned has me curious - are you saying that even brakes now are 'electronic'? As in no cable from the brake lever to the brake itself? Or, am I misunderstanding?

Separately, this... https://99spokes.com/...ubcategory=triathlon, is really cool.

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Running is the best source of fiber that I know of...

Shifting is electronic, brakes are hydraulic - I don't think anyone has been gutsy enough to do fully electronic brakes yet, but there are some ABS braking modules for ebikes now.

Hi Tony. When you say " Your options become limited and will continue to dwindle. ", do you mean for 'Rim Brakes', of that travel/maintenance issues will get worse. I am presuming the former. Also, what are the biggest 'challenges' in the learning curve here? Is it necessary to disassemble more in travel? Is constant 'rubbing' a lot of the issue that most people deal with?

Btw, I do agree they are 'here to stay'. The question is more, will the future will still allow options for both. As of now, it seems that it won't. Unless, the reasoning for not having both disc and rim has to do with some supply chain pandemic issues....

(although, I wouldn't be surprised if in the event they scrap rim brakes that in 5-10 years after the scrap, they do back in order to make more $$$ on new builds, frames, and necessity to revamp ones groupo between bikes...)

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Running is the best source of fiber that I know of...

Happy I misunderstood... Good to know. Cause that scares the crap outta me.... especially, since I am not one to charge batteries all the time.... i can deal with no shifting. but, in a pinch would like brakes....

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Running is the best source of fiber that I know of...

When I did the aero shootout at least 1 brand there admitted their design would have been faster with rim brakes.

Disc brakes were already the way of the future at that point.

Since then I've talked with another brand and they were trying to figure out how to make their disc brake bike they wanted to bring out as fast as the rim bike they currently had on the market.

i also suspect that one of the two big OEM brand's brake rotor has more drag than the other brand's rotor. On my list of things to test when I head back to the tunnel next year.

Also if anyone is interested in testing lmk.

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Brian Stover USAT LII
Accelerate3 Coaching
Insta

Another .02, this time from me: most of the forum members seem to be US based, with relatively flat courses on their mind when planning races. It’s a bit different in Europe, Switzerland especially. Not only are the races more hilly, but also more technical & twisty with 180 degree curves etc. Plus when the winter hits with salt & sand on the streets, you don’t have to be worried about your summer/race wheels so much if you’re riding discs.

IMO, the biggest advantage of disc setup are the through axles, and the stiffness they add. The biggest drawback is the disc maintenance: caliper adjustment to rotors, sticky pistons, bend rotors etc.

Disc brakes are slightly slower, so get a last gen bike and be happy. Tririg brakes and Hed Jet wheels will give you good stopping and aero both.

Manufacturers like to charge more and obsolete old equipment, but you'll be able to buy good used parts for a long time. The main advantage to disc wheels is being able to use carbon rims that don't need a brake track. Also, disc trispoke wheels have less of a penalty... ones with regular spokes need more spokes (that are crossed, not radial) to deal with the braking torque.

I think the key point is that in all reality, if you're planning to keep the bike for a few years, is that buying with a rim brake is buying straight into obsolescence.

There will be lots of wailing and gnashing of teeth from some. But it's just true. Give it time and getting rim braked wheels as an example that are 'cutting edge' will be increasingly hard. Same for other related components.
(Yes there will still be box section Mavic Open Pro rims that suit 23mm tyres with tubes for the next 4000 years. But that's not where the development is going). Rim braked wheels are always a compromise between the aero shape that is wanted, and having a flat parallel walls for braking).

There is no way I'd be buying a rim braked road or tri bike now. I've got enough obsolescence built into in 3 mountain bikes in the garage as it is, where the wheel sizes are different, number of sprockets different, BB different, axles all different, brake mounting points different, hub spacing different, and possibly the worst, headtube too small for any decent suspension fork from the past 5 years.
The road / Tri bike industry has taken up the same mantel.

The danger of rotors ? Overhyped by the neurotic. Feck me, have they never noticed their calf going up and down 90 times a minute about an inch away from a 56 tooth saw blade that's cacked up with shitty oil to maximise infection ?

I really don't get any ofnthe problems of brake rub that ate tslked about in some quarters. I've not had a problem with any disc braked bike I've had providing I occasionally clean the bike, and clean the caliper when I change out worn pads (And quite often I don't clean bikes between rides yet they still work OK unless there's a really bad bud up of dust - then I just get an annoying ching-ching-ching sound but no perceivable drag). I also love NOT having that shiity grey sludge on the wheels from rim brakes (and in turn my hands) that occurs every time I ride in the wet.

the issue is not the brakes. it never was the brakes. it's what you're able to do with wheels and frames because you're not encumbered by the need for rim brakes and calipers.

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Dan Empfield
aka Slowman

I’m the last person who could be considered a bike tech expert but I know disc brakes are inferior to rim brakes in pretty much every way unless you’re on a mountain bike. It’s a money thing. And yes they’re incredibly annoying. I’ve never had a single ride without the discs rubbing even after tune-ups at various highly rated shops.

Even pushing aside the fact that properly tuned disc brakes aren’t THAT big of a cost difference or hassle, they’re still inferior due to weight/aero/convenience/cost and are even more dangerous except in very specific circumstances, especially in pro racing where they’re forced on riders for sponsorship reasons and cause crashes constantly.

That said, for the average non-professional I barely think the performance aspects are noticeable and it’s more of a topic to casually complain about to pass the time. I doubt the Tadej Pogacar would be using rim brakes if he didn’t specifically push for them though.

Basically if you want a new bike, you're going to have to buy a disc brake bike. That being said, those bikes are no faster than rim brake bikes. That may change in the future but at this point you are basically getting a bike that's heavier, more complicated and possibly slower. The engineering gymnastics that had to be done to make bikes that were not slower than the previous gen rim brake bikes were pretty massive. My suggestion for most people right now is, get the bike you can afford. The upside of rim brake bikes is that they're relatively cheap and wheels are fairly easy to come by. FWIW, my road bike is disc brake, because it's newish. My TT bike is a Cervelo p5 from 2013. At this point nothing is faster, so I'll keep riding it.

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Heath Dotson
HD Coaching:Website |Twitter: 140 Characters or Less|Facebook:Follow us on Facebook

I’m the second to the last bike expert but what I haven’t read yet is disc brakes superior wet weather performance. Granted I avoid riding in the rain but both Wisconsin and Chattanooga were soaking wet on the bike. My carbon wheels with their matching brake pads are pretty much useless in the rain and I almost need to do a Fred Flinstone stop. And for reference I do have hydraulic discs on my road bike and have been caught in the rain. The difference is night and day!

What are the limitations to wheels and frames? I think there are zero. Some things I've heard:
- rim profiles: this one is nonsense. The brake track doesn't need to be flat or vertical for rim brakes. They sure weren't on my rim brake SES 7.8 wheels. Wheel profiles can be identical for rim and disc wheels.
- bigger tires and wider rims: calipers can be made with larger clearance. My grandma has a dual pivot caliper that clears 40mm tires on her 40 year old bike. Superbikes with proprietary brakes can have any fork/brake clearance they want.
- what about frames?

Meanwhile there is no way around the extra frontal area (and weight) of disc brake calipers, rotors, and extra spokes. Rim brake superbikes like the last-gen Trek/Canyon/Cube/Cervelo/etc literally just have the front pad and pad holders in the wind. Disc bikes have caught up to rim bikes in aero, perhaps. But just as disc bikes get innovated, that same effort would have made a modern rim bike even faster. So while you say that bikes were encumbered by the need for rim calipers, we could flip the argument and say disc brake bikes have just as many limitations in fork, wheel, and frame (chainstay) design. They are inherently heavier and less aero, require greater spoke counts, and need more support in the caliper mount areas.

The only upside to disc that I can see in the current product landscape is braking power, which is already easily matched on rim brake bikes with direct mounts, good pads, and textured aluminum rims. Can even go hydro, since that is a major contributor to disc brake power comes from, though that is also a source of pain in servicing brakes. So that leaves no downsides, really.

I've switched to disc because that's what available. But I still think they're worse in more ways than they are better. As some others have said, "disc is the future." No one argues that, but it's certainly up to debate whether that's the better technology, like-for-like.

Like-for-like being important to separate disc vs rim arguments from:
- 10 year old rim tech to cutting edge disc tech
- cable vs hydro

I think there's only a few new rim brake bikes being sold now, and once the current stock is gone no new rim brake tri/tt to be had: Quintana Roo, Giant, Cube.
Several years were needed, and now most disc brake bikes are as fast as the rim ones were.
Personally I'm still on rim brakes, but if I'd buy new I'd have to get disc. It pains me to have to build and maintain a disc brake bike, but I don't see a choice.

When you test, I’d be interested to see the top line rotors compared to their mountain bike counterparts. It’s my understanding the road bike rotors carry a lot of mass for heat dissipation under hard braking. Since Tri bikes don’t often do a lot of braking, it seems to me that the use of lighter mountain bike rotors would be smart, assuming aerodynamics are similar. When I built my wife’s road bike, I used XT rotors since she is just a recreational slow speed rider and they work fine for her.

We do have a new world champion (Gustav Iden) who rides a bike with rim brakes while his team mate (Kristian Blummenfelt) rides a superbike with disc brakes from the same sponsor (Giant).
This seems to have flown below the radar. I'm surprised how little it has come up in post race questions.

What TJ56 Said - I was caught in the rain 5 years ago with Rim Brakes and almost rode into in intersection at the bottom of Hill due to wet rims and brakes. My next Road bike had disc brakes and i have never had an issue and was very confident with them at IMWI 2022 when it rained all day on a hilly course.

To amplify this post... When folks talk about slower or faster, they tend to focus solely on the caliper and disk but ignore the total system. We are at the early stages of holistic aero & speed design around disk brakes, so the future will only get brighter.

Almost all bike design R&D is focusing on disc brakes. Therefore, it is unlikely that any future rim brake bike will be faster than its disc counterparts.

When you eliminate the design restrictions of a rim brake, it does some major things to bike design that can improve both aerodynamics and rolling resistance:

• Bikes can accommodate wider tires without aero penalties
• Bikes can have wider forks and chainstays for aero benefits
• Wheels can be wider to integrate better with wider tires
• Wheels can have different shapes, optimized for aero right up to the edge of the bead
• All-carbon wheels can be lighter since you don't need a brake track
• Frames are stiffer thanks to thru-axle (not purely a disc thing, but pretty much driven by disc)

Caveat: both my bikes are rim brakes, and I have no immediate plans to upgrade. I would really love some of the benefits, especially on my road bike, but they are both great performers and I do not feel like the expense and maintenance transition right now.

here's one example:

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Dan Empfield
aka Slowman

There a some design limitations with disc brakes too that aren't applicable to rim brakes:

• Strengthened spoke design requirement on front wheel
• Cooling of rotor/caliper
• Strengthened dropout/axle area due to asymmetrical forces
• Limitation of hub width by rotor

I do think disc brakes will prove to be a superior product aerodynamically in a number of years. The greatest limiting factor by far is the cooling requirement. There is no good (legal) way to cool the system without directing airflow over it, which is antithetical to aerodynamic efficiency (pumping loss). The only thing I can think of is increasing the mass of the rotor itself to become a heat sink, but extended descents would still be an issue.