But it’s faster! Who needs safety when it’s all about speed! ;)

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Thats certainly your choice, and i respect your concerns.

But once you have seen under the covers of how most of these frames are built, how they fail even without modifications, and how little it takes to bring them back up to safety.

I have a Cervelo P2 aluminum that i replaced the rear stays on with aero carbon tubes i layed up in my garage. It has 1000 miles and many jumps off of curbs. It was a confidence building project. Oh, brake platformed bonded under the BB on that as well. Cut the huge fin off to make that work.

I bought a broken Dimond after years of building mostly non load bearing things out of carbon. It was a foolish purchase, but the challenge was a huge pull. I have over 1000 miles on that frame after fixing an extensive crack in the seatpost collar caused by poor tolerances.

Added a brake mount under the BB of my Pearson. Its an 8mm chunk of carbon, bonded to the frame with 8 layers of UD. I tried to deflect that with a 15" crescent wrench. Its the strongest rear brake mount on any bike i have ever owned.

None of that will convince you that i know what I am doing, because that isnt the kind of guy you are. Likewise I could not stand to live life the way you do, being afraid of the unknown, and unwilling to investigate where the limits of my enginuity and engineering genius could take me.

Thats not an insult. People are who they are, and trying to be otherwise is a fools errand.

No, I'm an engineer who does research in a composites lab. I test and model composite repairs every day, working on a project to allow the air force to model and repair damage to their planes. I'm sorry you don't understand the limits of your material of choice, but I'm going to call you out every time when you are giving people dangerous advice.

Not just you. I have similar issues on my F-Si with XT 8000 brakes. I basically never have issues on any of my rim brake bikes.

This has to be one of the cockiest statements I have ever read on here.

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Whoa, whoa, whoa!

I gave no advice here. I stated the plan that I would execute. I didn't state the testing that would go into verifying that it was safe before returning it to its owner.

I take safety very seriously. I test everything I build to an excessive degree. I have one child and another on the way. I would never endanger my ability support my wife or children, and I would never modify a bike that I wasn't willing to ride myself.

I haven't had a stripped down P4 in my hands in years. I havent measured the thickness of the carbon under the BB, looked at how much of the internals are accessible from various locations and angles, etc. I wouldnt dig into the project without evaluating all of those possibilities first.

Calfee and others have been doing this kind of stuff for many years. There are 10's of nobody engineers that hand build entire frames without a minute of compute time spent on CFD.

Perhaps, the stresses of a brake nut are somewhat reduced compared to a many thousand pound air frame with jet engines strapped to it, designed to travel at supersonic speeds and ridiculous G forces.

If you had said to yourself "I wonder if i can figure out a better way to do this?" as many times as I have, then had the sack to do it, and find out that you could, then you would be partial to saying things like that too. To you it sounds cocky. To me, its the experience of being succesful at the things I spend my time on.

Its not the belief that others are bad at things, but the belief that you will not stop for any reason until you create it, test it, destroy the things you painstakingly build to find the limits of their strength.

I dont believe that I am smarter than other people. I believe that my will is stronger, and that my commitment is an unstoppable force.

Lol, ok. Have fun

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You had me right up until "en"ginuity.

Yeah let me explain because a lot of you fucks took your licks on this. I’ve decided that I hate the rear thru axle system on my Exploro, and I’m swapping hoops on that bike a lot — far more than any mountain bike which are set and forget. It’s hard to describe but the part you thread into with the axle disconnects entirely from the frame along with the rear derailleur. I get the idea but it’s just not that easy in practice to get the axle in not cross threaded. So I think I’m unfairly penalizing discs on the time.

I did have a rear flat once in Puerto Rico it took me 3:55 per my Garmin but a good 30 seconds of that was trying to find the right patch of actual dirt/grass that wouldn’t scratch the damn bike when I laid the thing down on its side.

How long is it supposed to take? I’m not fast but I’m not slow and In either case 3 or 4 minutes it basically ruins your race and makes everyone who sees your split think you can’t ride a bike to save your life.

Yes, but I heard you can't ride a bike to save you life!


Anyway, I never used thru-axles. I can see them on mountain bikes to stiffen things up but maybe not even of XC bikes. Why is there any need on a road bike?

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''Sweeney - you can both crush your AG *and* cruise in dead last!! 😂 '' Murphy's Law

Love where this thread went. It’s like a equipment crisis thread meets aerobullying meets reasoned dialogue about bikes meets emotional back and forth meets...whatever BryanD is doing which is just so special. With contribution from people who are actually making the bikes.

Very Slowtwitch thread. Carry on.

Any issues with water getting in between the rim and fairing when riding in a hard rain on those?

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"They're made of latex, not nitroglycerin"

Oh, don't pretend you're better than us! You're as emotional and melodramatic as an the rest of us. You don't get to troll us all with predictable results (and don't pretend your OP was anything but a troll), and then pretend you're "above it all."

Not really. Water can definitely get in there, but not enough that it "sloshes," etc, and it drains out pretty easy.

I think what is clear on this thread is that everybody from one end of the spectrum (Tom A) to the other (BryanD) is guilty of at least a bit of confirmation bias. I am too, because I've ridden bikes around the wet, steep, winding hills of West Yorkshire for many years now and I've never lacked for stopping power with my rim brakes. And I'm from Yorkshire so I'm stubborn and set in my ways. Caveat: I only ride wheels with alu brake tracks.

That said, when I get my next road bike it will probably have disc brakes. Not because I believe that the stopping power of a rim brake is limited.... as many folk have pointed out, if you can lock up the rear wheel then the pad/rim interface isn't the weak link... it is the rubber/asphalt (and water) interface. But... it is a shit load easier on the hands to brake with hydraulic discs. By the time I reach the bottom of some of the long descents around here I'm almost cramping in my hands... it takes less effort to brake harder in a hydraulic disc rotor system. Or at least it seems that way to me. I can cope with a bit of inconvenience swapping wheels out and whatnot for that. Sometimes it is more about enjoyment than performance, especially in training.

Unlike some others, I train almost exclusively on my road bike and ride my TT bike on the trainer or in races. I don't really buy into this idea of training on your race bike.. it is less comfortable, less fun, and less safe... mainly I just can't be arsed. I get my specificity from riding it indoors in the TT position, and it takes me about 30 seconds to get used to the different handling/braking when I eventually take it outside for a quick practice ride and a shakedown before I race. Might do one or two centuries in TT position if I'm going long that year.

So like Kiley, I'm likely to keep a rim braking TT bike as my forever race bike. It is a P3C and pretty much fully optimized for aero, and I'm in no hurry to change anything. I am confident that both the frame and the wheels will last at least as long as I do at age 41, racing 3 or 4 times a year. I might just stock up on brake pads before the rim braking apocalypse hits us.

Totally. And I wanted to respond to all of it now that I am all caught up but I kind of missed the window on replying live

I meant that in a positive way and also in the way that there is both really good information and thoughts in here and then really dense zealots and then there are people who are trying to figure out what makes a great triathlon bike and people who are hacking up a 7 year old frame because they can’t find a single bike that meets all the needs.

I do kind of just want a bike I don’t have to mess with much that fits really well and breaks down easy and has really great braking when it’s wet out and has a place for my flat kit and works and is as fast as possible. I really hope that happens for me — unlike chicanery and some of you other guys, I don’t do this stuff to tinker I just want the boxes checked of practical, easy, as fast as possible, and really really hawt. Also affordable. I’m a simpleton, really, but the obviously not everyone cares about those things.

If my bias is anything it is that I just don’t like anything that adds time to your race or complexity to ownership. Disc brakes seem to do both. But yet they are amazing. You know that when you ride them. Nobody doesn’t like the braking performance of a well configured hydraulic disc braking system, but we disagree on the rest of it.

With that statement, I think you hit the nail on the head ...

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Well...with downward facing dropouts and typical front caliper mounting location, there IS the possibility of the braking force causing wheel ejection. The solutions are to either a) change the dropouts to be forward facing, or b) use a thru-axle. The industry has decided to use option "b" because there's also a perception of making the structure stiffer (although if one compares the 2 structures, it's not really the case).

On the rear, they aren't needed at all. Most are done thru-axle just to be consistent with the front configuration IMHO.

That said, I agree with fredly that most folks would be able to operate a rear thru-axle better than a rear-facing dropout bike...although the correct comparison should be to a "normal" dropout style bike, since the bikes with rear facing dropouts usually do so for being able to get the wheel close to the seat tube cutout...which is something a thru-axle configuration wouldn't allow either.

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I'm not sure why I thought of this...

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http://bikeblather.blogspot.com/

I have not been amazed by hydro road discs. No better power than rim brakes and they howl as soon as there is a sprinkle of rain, or get filled with grit if I ride through a puddle. Which rather defeats the purpose of having a rain bike. The only reason to ride it is to keep the good bike clean.

The S5 may be my forever road bike (to go with the Eddy Merckx MX Leader, which is already a forever road bike). Soon I won't have room to try new bikes.
For tri, you know my thoughts. I'd be tempted to try a bike that could prove it was at the aero standard and had good geo, discs would be a minor annoyance if all the other things were right.

They may be here to stay - the question is are they faster?

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He who understands the WHY, will understand the HOW.

Yeah...same here. No better power nor "modulation" than a well-setup rim brake system...which often has me wondering just how bad are some of the braking setups people are riding around on? I also find disc setups to be a bit "grabby" in certain conditions...

BTW, speaking of riding discs in the wet...have you noticed that when it's really wet (like decently raining) that there's still that moment of "oh shit, nothing is happening!" when you first apply the brakes?

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For a bunch of reasons, I am not a fan of disc brakes for tri or TT, but I think that there are least two issues perceived with rim brakes:

Most people are riding around with stock brake pads on their rim brakes. And most stock rim brake pads are honestly pretty bad. On the other hand, if using AL rims, kool stop salmon pads should be the bare minimum performance standard (and it's a pretty good one at that).

Then, some people then have had the experience of riding around on typical carbon rims with typical rim brakes on occasion doing that in the rain, which of course can be insanely dangerous.

Most disc brakes perform either a little better or, in case no. 2, perform A LOT better than the above.

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