Nah.. they make sense because only the most pain loving home mechanic would fix a broken internal hydraulic hose instead of taking it to the approved bike dealer and paying a couple hundred bucks to have it done.

God that sounds bad! (Yes I get that in normal routine maintenance that hydraulic hose will be way less trouble and last way longer than brake cables run internally.)

out of all the new disc-brake equipped aero bikes, only the Cannondale seems to be worth the trouble.

Otherwise, manufacturers are contorting to get people to buy the disc-brake bikes. The 2016-2018 Trek Madone was a fine rim-brake bike, but that bike would have been faster than the 2019 disc version. So Trek made the 2019 rim-brake bike slower as well, just so they can say that their disc-brake equipped bike is faster than the corresponding, same-year, rim-brake bike.

Irony here is that a rim-brake Cannondale would likely be faster than the disc-brake C'dale, but I don't think C'dale would be debuting that bike any time soon.

relax guys. everyone's had shower thoughts that withered in the light of day.

besides, we all know coaster brakes are the most aero.

This seems to be borne out by a recent Tour Magazine test of the latest aero bikes. A link to the test and a discussion of it can be found here:

https://weightweenies.starbike.com/f...p?f=3&t=154692

Here's a summary of the results:

The aero road bikes from every manufacturer in the test got slower when they redesigned it for disc brakes, except for Cannondale. But even for the Cannondale, they redesigned and re-optimized the entire bike, so who knows whether redesigning and re-optimizing around rim brakes wouldn't be faster still?

I've read the Cervelo white paper on the S5 Disc, which claims that the S5 Disc is faster than the previous S5 (no surprise there - every manufacturer claims their new bike is better than their old bike). But if you look closer, you'll see that they changed many aspects of the design (such as routing all the cables internally through the special stem, headset and fork). They mention how much power each change saved, and it adds up to more than the power saved by the whole bike - which implies that switching from rim to disc resulted in a power loss, for which they had to redesign other parts to make up for.

It's a good thing these bikes will have discs, since with all the improved aero on the frame it might require greater application of brake forces to stop while coasting to a red light . At 5-8 mph, the average rider needs confidence they can stop comfortably and safely, with plenty of margin for error.

See, with a little editing, the theory in the original post is true, and the poster vindicated! (I just needed to clip out the parts about flat roads and relative braking performance.)

Unless these were all tested in the same session there's too much margin of error to be valid.

someone on slowtwitch independently stated (with evidence, though can't seem to find it right now), that the older Trek Madone was more aero. He expressly advised that I buy a new old stock Madone rim-brake when I was contemplating buying a new bike, stating that neither the newer rim-brake nor the disc-brake matched the older rim-brake. That was why this report resonated

Okay that was said, but based on what evidence? Unless they were tested side by side in the same wind tunnel session it's inconclusive. Trek isn't going to spend time testing that (or publishing if that's the case). I doubt any privateer would spend the time/money.

Even if it was tested properly and the results were 8w I personally would prefer the disc bike. I tried the rim brakes on the Madone once and wasn't impressed. I sure as heck wouldn't want to service cable brakes on that bike either. Once installed, there's really no reason to ever go in and replace any of the disc brake system year to year.

apparently Trek's own white paper

http://trek.scene7.com/is/content/Tr...aper_EN-GB.pdf

note that the difference is well on marginal (1% faster for the older one), but this doesn't add all lend credence to the assertion that disc-brake frameset is faster

All this tells me is that for each manufacturer the rim and disc versions are pretty damn close and not worth getting excited about. You are free to choose which version you want with basically no aero penalty.

As much as I love my rim brakes and don’t really see the point of discs on a pure road bike, I don’t think the big manufacturers will be putting much R&D into rim brake optimization. Almost all the world tour teams are on disc this season.

Within margin of error. That's not a clear difference.

Hey I'm skeptical that any of those bikes are significantly faster than my old Cervelo S2. I've got much smaller frontal surface area on this bike than the current fat tubes used.

https://photos.smugmug.com/Cycling/T...6_200146-L.jpg

https://photos.smugmug.com/Cycling/T...1_105748-L.jpg

Wait...how are these people up in arms over disc brakes, but they are okay with direct mount brakes?

I would tend to agree with the S2 being hard to beat aero wise. I’m still using my 2008 cervelo SLC-SL and my my soloist team. They are both getting long in the tooth though.

which is to say, we shouldn't trust the ad copy saying that disc-brake is faster

i don't know about your riding style and attributes, but i was the type to go for any little aero advantage possible back when I raced. I couldn't accumulate points from sprinting, so I had to get away solo or in a small group, and aero helps there.

The S2 was ahead of its times, and i'd venture that few framesets represent a significant upgrade over yours (earlier S5 being one of those)

only minor quibble is that you can save a bit more by using an aero road brake such as the Tririg Omega

I guess that's what the bike company marketers want you to believe (and it looks like you've been drinking the Kool Aid). But when this was discussed a few weeks ago, it was found that the majority of world tour teams are not using disc brake bikes (10 out of 18). Of the other 8 teams, 4 are using a mix of rim and disc brakes, and only 4 are using disc brakes exclusively.

https://forums.thepaceline.net/showthread.php?t=233038


I suspect that it has nothing to do with extra aero drag, and the reason racers use rim brakes instead of discs is similar to why they use tubular tires instead of clinchers:



By many measures clincher tires give a performance advantage over tubulars because clinchers have lower rolling resistance (and also often lower aero drag as well),

BUT:

The performance advantage of clinchers over tubulars is very small, and because clinchers are more prone to pinch flats and can't be ridden as fast when flat, the risk of losing a lot of time due to flat clinchers is of greater concern than gaining a little bit of time due to their lower rolling resistance.




By many measures disc brakes can give better braking performance than rim brakes, by giving more consistent brake performance over a wider range of conditions.

BUT:

The time gained due to the braking performance of disc brakes over rim brakes is very small, and because disc wheels are slower to change and disc brake wheels have more interchangeability issues, the risk of losing a lot of time with disc brake wheels in case of flat tire or other wheel problem is of greater concern than gaining a little bit of time due to their more consistent performance.

Come On Spring!
 

Coaster brakes were so rad!

Agree on both accounts. I'd say all these aero bikes are pretty damn slick compared to the old, round tubed bikes.

You can get very close to these car-priced bikes for a lot less.

I've been thinking about a more aero front brake for a while.

Sent from my SM-G950U using Tapatalk

Ha, ha no kool aid here! I’m still happily using my 2005 and 2008 cervelos for road cycling. I could care less to be honest, but it doesn’t take a genius to see where this trend is going regardless of the actual number of teams using disc bikes right now.

I’ve seen this story play out in the bike biz with many changing standards over the years.

It’s clear to me that the majority of R&D is going into disc brake bikes and not rim brake bikes regardless how anyone feels about it.

I grew up in the 50-60s. All we had were coaster brakes and they seemed fine on our 35lb Schwinns, Murrays and Rollfast models. Then Bob got a 10 speed "English" bike around 1964. I'll never forget the first time I pedaled backwards to apply the brakes. Crap that hurt.

Truth
 

[QUOTE=Bonesbrigade;2499470]Ha, ha no kool aid here! I’m still happily using my 2005 and 2008 cervelos for road cycling. I could care less to be honest, but it doesn’t take a genius to see where this trend is going regardless of the actual number of teams using disc bikes right now.

I’ve seen this story play out in the bike biz with many changing standards over the years.

It’s clear to me that the majority of R&D is going into disc brake bikes and not rim brake bikes regardless how anyone feels about it.[/QUOTE]

Exactly.

I found a video of Tom Ritchey on YouTube to be pretty informative. It's titled:

Tom Ritchey Q&A With fahrstil


He starts talking about aerodynamics and drag at about 42 min into the talk, but the whole clip was worth watching.


As a user of disc brakes, I couldn't imagine riding a mountain bike without them. That being said, my main challenge on a road bike is not slowing down, but going faster.

Finally, I will not rest easy until disc brakes come stock on balance bikes. Shoe life will be increased.

As more bikes become disc brake only, wheel designers will be able to play with the rim shapes to make them more aero, this is where a load of benefits will come

My own experience: I was riding my TT bike in Ironman Zurich (appologies to all Triathlon haters). Climbing Heart Break hill, supporters shower the riders with cool water, however, immediately after HB Hill, there is a short technical descent, I hit my brakes at 35-40mph to go into the first corner, my brakes and wheels were wet, it was clear I wasn't going to make it, so I bailed and went straight on, crossing a small traffic island, and mounted the sidewalk, luckily there was a dropped curb on traffic island and sidewalk for pedestrians. My next TT bike will have discs.

Tri Try Tri
 

I think it was Cervelo who determined that for the bike itself, the biggest factor for aero was the handlebar shape by far.

Tri shows that the rider and his/her position and clothing mean more than negligible losses below anyway.

I don't do Tri but I like the bikes and tech that go into them.

I'll believe that when I see it. Many times potential advantages have been promised, and yet they never come to pass. We were told that tubeless tires would be lighter, have better traction, and lower rolling resistance, yet this hasn't happened. We've been told that disc brakes will allow wheels to be more aerodynamic, but this hasn't happened either. Exactly how do you imagine that rims can be reshaped for aerodynamics that rim brakes don't allow? Some have clamed that disc brake wheels don't need to have parallel sidewalls, which is true - but neither do rim brakes. I've got several sets of rim brake wheels with sidewalls (brake tracks) angled for aerodynamics.

This may be yet another case of counting your chickens before they hatch.

Truth
 

It's old news and well known that by removing the restrictions that rim brakes held over wheel design it opened up possibilities that weren't there before.

Whether it matters a whole lot to many people is another matter.

That's just repeating prior unsupported claims. Well known by whom? Where's the evidence?

Easy Tiger
 

Relax. Rim brakes will be available on bikes for years, maybe not on certain brands or models, but they will be there.

We've all done this dance a hundred times.

Tubeless tires are at the top of the list. In general they are competitive in weight and rolling resistance while greatly increasing the chance a puncture won't stop you on the side of the road.


https://www.bicyclerollingresistance...d-bike-reviews

Hilariously there are lots of Walmart super cheap bikes with rim brakes that have angled rim sidewalls... it is not a cost thing.

This stuff tends to be a bit hilarious.. < 10w at 27mph. I can't TT at 27mph. I don't even race anymore. Not going to worry about it.

It seems the Pros aren't worrying a lot about a lot of it either when they keep choosing the rim brakes even when the discs are supposedly so much better, etc...

Even when you've got the guys at the razors edge at the top of the sport it so often seems like the races are determined not by these aero engineering items but whether a given rider has something going on with their back that prevents them from hitting the optimal riding position for aero, or whether another rider seems to have an attention issue and crashes.

Ignoring the dope they were both consuming no amount of aero advantage would ever have allowed Ulrich to beat Lance in the TdF. Lance had that back shape thing that hurt his aero probably more than anything Trek could have done to his bikes, but it didn't matter when Ulrich failed to keep the rubber side down so many times.

As for tubeless I think all those claims have borne out on the MTB side.. I think if we all changed our mind and were clamoring for tubeless road it would spur enough R&D the tubeless tires would start improving more rapidly. Chicken and Egg?

The biggest reason for a pro to skip disc brakes right now is the thought of trying to get a spare wheel in a race. The other stuff is minuscule in comparison.

As far as aerodynamics for disc only wheels, since you no longer need a flattish brake track could wheel designers more fully optimize the shape of sidewalls to improve wheel/tire intersections from an aero perspective?

I do not know if the above is possible, just asking the question.

I think you mean A tubeless tire is at the top of the list. This particular tire is also very lightweight and notorious for being delicate and flatting easily. (It's also not a true tubeless tire - instead it is Tubeless Ready.) There is no standard tubed version of the Vittoria Corsa Speed TLR to compare it to, so we can't know if it would be even better in a standard tubed version. But if you did a careful comparison of otherwise similar tires (i.e., similar size, tread thickness and casing toughness), I believe you'd see that tubeless tires show no clear advantage over standard tubed tires.

Another comment on the www.bicyclerollingresistance.com tests: These tests are a bit biased against standard clinchers, as their test procedure uses a relatively thick and lossy tube, not a low rolling resistance tube. Another test on this site show that latex tubes or thin butyl tubes will lower rolling resistance substantially, but they have chosen not to do tire tests with these tubes. Other testing groups that that do use latex tubes have shown that with these tubes, tubeless tires generally do not have lower rolling resistance.

Maybe, but it hasn't really been demonstrated yet. Also, it should be noted that flat, parallel brake tracks on rims is a relatively recent innovation (just the last couple of decades). Before that, rims commonly had curved and/or angled sidewalls. There were even some rims with concave sidewalls.

Here's a popular rim from the 1980's, the Campagnolo Lambda Aero:

http://www.bikepro.com/products/rims..._v_section.jpg

And even though sidewalls are typically flat today, not all of them. Here some more modern Zipp rim brake wheels - which are clearly angled and curved for aerodynamics:

http://zipp.com/_media/images/dynami...imProfiles.jpg

https://c1.staticflickr.com/7/6084/6...7c36704353.jpg


Would these rims be shaped differently for disc brakes?

Top 2 tires are tubeless. Next in line is tubular. The top clincher isn't an everyday tire either. When factoring in a latex tube as they suggest in more detail in the reviews the clincher would perform along side the tubeless tires. Keep in mind people with carbon clinchers and rim brakes are advised not to use latex tubes. This segment of the market (the ones that care most about these details) is more likely to own carbon wheels so you can assume they can use latex tubes.

Bottom line, like the brake arguments here you can't say one is a clear winner and you should just buy what works for you. To say that tubeless tires are at a distinct disadvantage to clinchers hasn't been the case for quite some time now and there have been great improvements in tubeless tires especially in the last 2-3 years.

I assume a lot of the pros choose rim brakes to save weight. Contador used mechanical groupo until very recently IIRC to save that 200g of weight on mountain stages. When you have to climb 3 everest mountains every grand tour, the lightest bike is the way to go. I assume the same for aero bikes, i have not seen 1 aero bike in any size that's even close to 6.8kg. Until disk brakes become lighter than rim brakes, pros are going to stay with rim brakes.

Which is of course why I never claimed that tubeless tires are a distinct disadvantageous (for rolling resistance). As I think we've both shown, they are roughly on par, with no clear advantage one way or the other. But that's not what has been claimed in the past - many people promised that tubeless tires would be better.

There have been many claims about disc brake bikes/wheels having an aerodynamic advantage. We may have to wait a bit more for definitive data, but from what we know so far, they have not yet proven to have the distinct advantages claimed.

Both disc and tubeless for performance road are in their relative infancy. Seeing how fast there have been legitimate development tells me we haven't reached any sort of peak. You can't integrate rim brakes into the frameset like you can disc. The ones that have tried (Trek, Specialized, Ridley) have had relatively poor performing caliper brakes. Tubeless tires have gotten significantly more supple and better performing in the last couple of years. The difference between my current Schwalbe Pro Ones and the first Hutchinson Fusions I had is big.

"Fusion power is the energy source of the future - and always will be".

"Where's the my flying car?"

I don't make equipment decisions based on promises for the future, I make them on current performance and characteristics.