Just realized the irony of disc brakes on an aero bike.

[Hawker]

Originally Posted by vqdriver

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

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

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.

[Burnette]

[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.

[sipmeister]

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.

[mattsurf]

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.

[Burnette]

Originally Posted by mattsurf

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.

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.

[Mark McM]

Originally Posted by mattsurf

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.

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.

[Burnette]

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.

[Mark McM]

Originally Posted by Burnette

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.

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

[Burnette]

Originally Posted by Mark McM

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

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.

[ergott]

Originally Posted by Mark McM

We were told that tubeless tires would be lighter, have better traction, and lower rolling resistance, yet this hasn't happened.

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

[benb]

Originally Posted by Mark McM

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.

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?

[ergott]

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.

[EDS]

Originally Posted by Mark McM

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.

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.

[Mark McM]

Originally Posted by ergott

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

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.

[Mark McM]

Originally Posted by EDS

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?

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:



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:






Would these rims be shaped differently for disc brakes?