BICYCLES

My LBS explained to me that discs are a LOT heavier and less aerodynamic. My current rim brakes are more stopping power than I need... I can can make the wheels skid. Then there is the reliability issue if you touch them and oils get on the disks. What are your thoughts?

 

eTap hydro groupset is 285g heavier than the mech brakes version.
Bontrager Aeolus 5 disc wheelset is 118g heavier than the rim brake version.
With the frameset it will be negligible.

I would highly suggest heading to your lbs and test riding any hydro disc road bike. It was a revelation for me and most people have the same feeling. In dry conditions, as you note rim brakes have around the same ultimate stopping power. However the modulation and feel is SO much better with hydro disc. In wet conditions disc destroys rim brakes in every way. Rim brakes just end up being a very blunt instrument in comparison.

On the Domane SLR the disc frameset also has the advantage of being able to take up to 35mm tires. In pro racing and otherwise, the trend is toward wider tires not just for comfort but also speed. They have already moved up to 28mm in racing and on cobbles even 30/32. My experience also has been that on less than perfect pavement, wider tires at lower pressures is faster (and way more comfortable). Boonen took the first ever UCI win on a disc bike recently.

This recent test done by a Phd Aero, Cannondale engineer found that disc brakes had marginally Less drag.

Disc and Rim Brake Aero Drag - Slowtwitch.com

If I'm honest, I only pay attention to weight in wheelsets. The rest of it just doesn't matter unless you're racing at a pro level imo. Plus or minus a pound or so is the equivalent to a visit to the bathroom. I say the following very broadly speaking: it's especially ridiculous when I see middle-aged guys with guts obsessing about their bike's weight.

If you plan on keeping the bike a while I think you would regret not going for disc. Disc brakes and wider tires are in the fast approaching future. Or arguably the present; Specialized sells the new Roubaix only with disc.

Good luck, it's a beautiful bike!

 

The wind tunnel test results from the Disc and Rim Brake Aero Drag article are BIASED and likely BOGUS. The article does not describe how the test results are actually gathered. When we performed tests in our medical research labs, the first thing we described in our reports were our test setups and methodology, how we measured and calculated our results. This article only discussed what brakes were used.

We have no idea of even the wind speeds being used, how that wind was distributed vertically or even where the drag sensors were located. All tests involve some level of simulation of reality and such simulations need to be explained and justified in order for people to properly understand and interpret the test results. This is completely missing in the article. What is discussed in the article is simply conveniently used to support the conclusion of the CANNONDALE COMPANY AUTHOR. TE AUTHOR IS NOT IMPARTIAL - his employer would really like to sell more bikes. This is a CANNONDALE ARTICLE and CANNONDALE HAS POOR ROAD BIKE SALES, needs new products.

Notice the curious difference in drag characteristics when yaw angles are negative vs positive... do you know why? It's probably because when the bike is pointed to the right (negative yaw), the wind hits the big brake rotors BEFORE they hit the spokes.

And then when the bike is pointed left, the Cd deteriorates for all configurations probably because the wind sensor is picking up the wind hitting the chain rings - why is this not being picked up anyway when the bike is pointed to the left???? They don't say. I'm sorry but the chain rings are still there when the bike is pointed left so the way they collect their drag data and the way they interpret drag are likely biased... to create data that support their argument and not because they simulate reality more accurately.

BTW, I think Cannondale bikes, as nice as they are, they are of very antiquated designs. They cooked up the tests in this article using a current Cannondale TT frameset of antiquated design. My TT bike is a BMC TM01, first used on the TdF, way back in 2011. It's been superceded by a new BMC model but the 2011 bike is still lightyears ahead of most current TT bikes including the ones from Cannondale.

To make a proper comparison of TT bike brakes, Cannondale should compare its best with at least good alternatives, regardless of brand. So here are photos show how the article's disc brakes on its TT bike compares against the old BMC's:

FRONT BRAKES

These are my BMC's front rim brakes...

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...compared to the Cannondale's front rim brakes...

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REAR BRAKES

The BMC brakes, custom-made by TRP are recessed and set behind a cowling that is integral to the BB. The Cannondale uses regular Dura-Ace brakes which protrude massively and the cowling is a plastic tacked-on piece.

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It's not even close.

Here are the Cannondale disc brakes. Ask yourself how they would possibly be more aerodynamic that the BMC's brakes.

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Anyone who has lived knows there is a lot of BS in the world. Cannondale's article is one of them. They are far behind in product design and they are trying to do a cheap facelift by tacking on poorly-integrated brakes made by someone else.

Now compare BMC road bikes versus Cannondale road bikes.

IMO, some bike and bike accessories manufacturers are having financial problems and are using an ill-conceived disc brake concept to sucker bored bike owners into buying new bikes and new wheels. It's a cheap way to get customers to buy a lot of merchandise and the brake manufacturers do most of the work.

The high end bike industry got really greedy and expanded very quickly so now the industry has problems with their bloated fixed costs. They ran out of compelling reasons for their customers to buy more bikes. It's not like the used Fcars market where Ferrari is smart enough not to make too many Fcars and actually improve palpable performance in newer models. Don't get me going on NA vs forced induction, we all know why Ferrari is using forced induction.

Think about it, once you have 4-10 top end carbon fibre racing bikes of various varieties (and don't have accidents), why would you need yet another one? Just look at the fancy bike shops in your area and wonder how they are going to get customers to buy another 2-4 new bikes. Remember what bike shops and their owners looked like when you were racing bikes in your youth?

If you have good rim brakes you don't need disc brakes and one of the big arguments against disc brakes is actually the poor modulation characteristics of disc brakes when compared to good rim brakes. It's akin to comparing boosted electronic steering against the unassisted steering of the ALFA 4C and Lotus Elise.

Disc brakes were designed to quickly haul down heavy, mud-encrusted MTBs, potentially in very unfriendly and dangerous off-road conditions, not finesse and bleed small amounts of speed off aerodynamic racing road bikes carving fast corners... totally different design goals. If you ride aero bikes, it makes ZERO sense to use disc brakes - have you wondered how brilliant a bike maker must be to design disc brakes on any bike that they extol aero advantages? VERY DISHONEST.

IMO, if your brakes don't work well enough, it's not because you have rim brakes.

 

Michael, you won't get any argument regarding aero on a TT bike. I don't know enough about bike aero to offer a meaningful debate and not a fan of Cannondale nor turbo engines.

What I do know is that even 105 hydro brakes work better than the best setup rim brakes. Self-adjusting pads, more predictable and better stopping performance in wet conditions, next to no worry in long descents, and much better feel.

My suggestion for someone bike shopping.. just go test ride a hydraulic disc brake bike. You'll either love it and switch, or stay status quo. Nothing to lose.

Another aero test for your disapproval. On the Tarmac they found slightly more drag on the rotor side and no difference head on.

[ame]http://www.youtube.com/watch?v=HXQuSnKkS-I[/ame]

 

I dont have many hills where I ride and I wont be riding in the rain much. last year I did twice. Other than that, there was always a dry time of day. But just for consideration, what wheel and tire combo would you recommend if I did get the disc version? (ANY WHEEL, doesnt have to be Bontrager.)

e

 

Thanks for this POV. When I first saw this thread I glazed over your comments earlier. Once it became relevant to me, I remembered the post and searched for 2 days before I found it again! (I wasnt even sure it was FChat.)

 

None. I just use a thin layer of grease between the steel bolts and the aluminum rings & crank arm. If they're torqued to spec they should never loosen.

 

Vig, thanks for your message.

The video you used to argue your point used a Cannondale TT aero frame so my critique used the same criteria. At ay rate, bikes nowadays are all AERO. No bike frame maker will ignore aero so additional wind resistance is always a negative on a road bike. The reason is simple. Road bikes are ridden to much high speeds than MTBs which disc brakes were designed for. Wind resistance is not a significant factor when riding trail. That should tell you something about the inappropriate application of disc brakes for road bikes.

Your other video (from Specialize), which is quite flawed, actually says rim brakes have less resistance and saved time. However, there are actually at least 2 major flaws with this test:

1) I noticed the fans used in the video are all mounted a fair distance above the floor and are aimed straight ahead. That means most of the wind is concentrated on the rider and the area where rim brakes are mounted and less wind is aimed at the wheel hub locations where the disc brakes are located.

2) there are metal support frames located at the level of the disc brakes (see the RED CIRCLED AREAS shown below). These frames cause considerable air drag and since they are present during all the tests, they will mask the air drag that the disc brakes would otherwise create. They have the same effect as you would have if you placed a wire cage in front and behind the headtube and seat tube of the bike frame and tested wind resistance with and without a set of rim brakes.

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These tests are not done with sincere attempts to produce objective results. Specialized is trying to sell you the idea of buying disc brake Tarmacs. Aside from being a research scientist, I was also at one time, a product marketing manager at a Fortune 100 company. If these guys really wanted to compare wind resistance differences between the brakes they would aim the fans equally at the brake locations. They don't have to aim at the rider's torso, shoulders or head at all. In fact, the brakes don't even have to be mounted on a bike. They just have to place the brakes alone in front of fans but then the results would be dramatically negative for disc brakes.

I have always used Campagnolo brakes on racing bikes as have many professionals and elite riders for decades and generations. AFAIK, nobody has complained about inadequate stopping power from Campy brakes. Have you ever owned Campy brakes? They stop incredibly well. The limits to stopping from a set of Campy brakes are not the brakes, they are the CONTACT PATCHES ON THE TIRES.

Most people forget, it's the tires that ultimately stop the bike (or car). If the contact patches do not have sufficient traction on the road surface, it doesn't matter if your brakes are powerful enough to immediately lock your wheels, you will skid off the road and crash all the same. It's actually the ability to modulate your brakes that allow you to brake at the limit and not skid. This means it's the tires and how well you control their traction that matter. You can modulate better if you have direct control, not control via electronics and hydraulics.

Other rim brake riders have already attested that their brakes are strong enough to lock their wheels so what is the point of spending extra money to buy heavier, non-aero and more complicated brakes... and REPLACE ALL YOUR FRAMSETS AND WHEELS? Isn't that extremely foolish?

OK, I have work to do. I have to create an illustrated set of instructions for a shipper who is packing and shipping me an antique so I'm going to be very busy for quite a few hours. I hope my points are clear - people who in business to make money do not waste time and money making tests and post fancy videos for the public good. THEY ARE EMPLOYEES AND THEY DO IT TO MAKE MORE MONEY FOR THEIR EMPLOYERS.

However, if parents, spouses and friends of bike riders who were killed or injured in bike accidents sponsored a number of objective technical studies professionally-conducted by real scientists and found tangible fault with rim brakes, that would be a different matter.

As always, when someone is trying to sell you an idea, you should critically examine the subject item, analyze the arguments, consider who the messenger is and consider your own experience, before you believe anything.

Good day!

 

Are your feelings just as strong for someone who was going to get a new bike anyway? What about the remarks above about running wider tires on disc bikes? Never heard that before. Thought wider tires were slower.

e

 

Michael, that video was posted in jest. A 2min YT video wasn't meant to be offered up as a serious argument for disc brakes. Particularly as they found the disc version to have slightly higher drag.

Descending and wet conditions aside.. as I posted before, in dry conditions the absolute stopping power is similar between rim and disc brakes. But the the feel and control is far better with hydro. It's an opinion shared by many many riders.

At the end of the day, I am not racing and certainly not racing professionally. Safe to say that applies to, not all, but many of us in this thread. If something completely positively transforms the feel of an aspect of riding, I am ok with it if it is slightly slower. Each one can judge whether the transformation in brake feel is positive or not. Most consider it to be so. Like I said in the previous posts.. if a new bike purchase is in your future, test ride a hydro disc bike. At the end of the day- as always- that will be the most important step to judging its worth. You have nothing to lose.

Good luck with your purchase Enzo. Disc or rim brake, Domane SLR is a fantastic bike.

 

On the BB had to carefully wrap-on kevlar and carbon fibers to repair a crap weld attempt made by the PO. Epoxy / CF seems a very versatile and manageable technology for frame repair, based upon the wide use on boats , cars and aircrafts. The Saccon skeleton stoppers do complement tiny brake levers have for a different set-up .

 

Those fans are drawing air past the rider, in the opposite direction of your arrows.

Any good research scientist would look at all possibilities, not just the ones that confirm the "researchers" bias.

Don't quit your day job.

 

Thanks, I'm not the only person with such opinions.

Here's an online reviewer of bicycling magazines from November 2015 "The Great Disc Brake Swindle?".

The article doesn't address the latest disc brakes but regardless of that, some of his points bears consideration.

 

You bring up several points.

First of all, the arguments for wider tires were that the contact patches would be wider, provide more grip, corner better and also allow you to reduce the air pressures so it would soften the ride. The current thinking is that 25 mm tires are a good bet and some people even want to use 28 mm.

However, I think people should also put other factors in perspective before going out to buy new rims and tires. For example, just how heavy are you, how fast and what kind of riding do you do? What kind of roads do you ride on? Just like cars, it's not always a good idea to put the widest set of tires on your car. There's also the tread design of tires as some tread designs already wrap around the edges to provide better cornering.

In the old days, we rode on rock hard 18, 19, 20 mm tubulars, but we also didn't have lightweight, sometimes very stiff CF frames and we also had 3-cross low-flange hubs. I also only weighed 145 lbs those days. Nowadays, recreational riders and even some pros have gotten heavier so wider tires could make sense for them. Cobblestones are common in many bike-crazy European countries so extra air at lower pressures would also make sense for riders there. I'm still fairly light although no longer at competitive weight but even now I only put 85-90 psi/110 psi FR/RR in my tires.

Wider tires would also be heavier and present a larger Cd. So maybe using 23 mm in the front 25-28 mm in the rear might work better? At any rate, rim brakes already support these sizes. I just had a look at the 2016 Campy BORA wheels used by the pros and most are 24.3 mm wide. I imagine Campy rim brakes work with Campy wheels so I think Campy rim brakes work just fine with wide tires.

So I hope you can appreciate the complex relationships between a myriad factors you should consider before just buying wider rims and tires. Industry hype usually focus on single seemingly "miracle" factors but I think it's unwise to restrict decisions to a single dimensional change but unfortunately that's what some people want us to think, because they would like us all to buy new stuff and more stuff.

As for someone buying his first and only road bike, I would stay away from disc brake bikes. Most of the really good bike kits are not disc brake compatible. IMO, it's a scam. Disc brakes only work better in the wet if you go silly speeds in rainy weather but they detract from other aspects of road bike design and may be a nightmare to maintain. Read the online article I linked to in my earlier message.

I am in the market for a very light frameset and wheels for tackling hilly terrain but I have no need and no interest in disc brakes for a road bike. They make no sense at all to me.

 

Sorry, I didn't realize you weren't serious about the video. IMO, there are also problems with that testing setup. Kind of confusing all around I guess.

I haven't tried disc brakes as I don't go off asphalt surfaces and already use the best rim brakes on the market so disc brakes don't provide me any advantages, only waste of money but many disc brake owners and reviewers do complain about grabby disc brakes, discs rubbing. Campy brakes are a bit pricey but are not without benefits. IMO, they make the best rim brakes.

I can appreciate your sentiments about cycling but perhaps I have different expectations from my cycling experiences. I bike for health reasons as well as for fun. The fun part is similar to why I enjoy the F1 technology used in my Fcar. Like many Fcar owners, our cars make it feel like an occasion every time we drive them. So it's the same with my bikes, which are equipped the same as bikes on Pro Tours. I'm surprised you don't understand that adding a disc brake road bike would be poison if you already own expensive rim brake wheels and bikes. I swap equipment between my bikes. I minimize tools that I need and have no interest in maintaining hydraulic equipment. I already ride on the best bikes and equipment. I'm already very happy.

You might also enjoy this objective review of disc brakes pros and cons. You may be surprise about what it says about disc brakes and wet braking.

 

LOL, mystery solved on the "3-D surface effect" in your BB photo. It actually looks quite neat, and complements the exposed CF of the frame.

The brake levers do look a bit smaller than usual. Are they also by Saccon? Interesting shape.

 

Thanks for pointing out my mistake in the wind direction but ironically, I don't think it makes any difference in this case. I also think the tests might have worked better if the fan could direct air on the bike rather than just sucked air past it. I say this because the design of the Specialized wind tunnel appears to me to be flawed for this application.

I made a reasonable drawing showing a cross-section of the Specialized wind tunnel. I also thought about the probable air flow in such a wind tunnel using the assumptions that air flow would follow the shortest path of least resistance, that air flow slows when encountering solid surfaces and that air flows of different velocities create vortices or eddies which would reduce air resistance.

Please note the drawing I made only shows the pattern of air flow and does not show the turbulence caused by the rider and bicycle. I do this to emphasize the different velocities of air within this wind tunnel and thus to illustrate a "flaw" in the wind tunnel design with respect to the requirements of the testing of disc brake vs rim brake air resistance properties. I think this wind tunnel is not appropriate for this test.

Most wind tunnels are used to refine the frontal aerodynamic shape of a speeding object, not to compare the relative Cd of one part/location on a slow moving object to another part/location on the same object. It's complicated but this is the main reason why this wind tunnel is not an appropriate test environment for comparing the brakes.

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The blue dashed lines indicate air flow with the thicker lines representing higher velocities. Higher velocities are exhibited in the middle of the air flows being sucked into each of the 6 fans. It's a little easier to visualize if you imagine the air flow as a river flowing left to right and splitting into 2 separate tributaries on the right. Vortices, pools and eddies are formed next to the banks and coves, as well as in the "dead spot" between the 2 tributaries.

My argument, if I am correct about this airflow pattern, is that this wind tunnel does not accurately simulate natural wind. While this would not compromise refining an aerodynamic shape, the lower parts of the bike where the disc brakes reside would be subjected to lower velocities of airflow so the wind resistance created by disc brakes is unrealistically low for this test.

Natural wind is complex and can come from any direction so a wind tunnel with an artificially uneven wind pattern built-in is inappropriate. The best test environment would be a homogeneous wind pattern. The test would work much better if the tunnel used a much larger number of smaller fans with the bike and rider elevated on a platform so that they are close to the middle of the tunnel, like the one shown below.
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Unless I rode normally in the rain, snow, mud, or mountains, I wouldn't buy road discs. I've always been very happy with aluminum rim brakes and salmon Kool-Stop pads, and discs can be difficult to modulate and noisy. They're not worth the penalty on a road bike ridden in the dry on flat roads.

 

I can certainly understand the reluctance of someone purchasing a disc bike if that are a flat lander as there is little to gain but weight and added complexity. However, having ridden a disc equipped bike in the hills recently, I can guarantee my purchase this year will most definitely be disc. Great feel and as someone who on occasion rides in the mountains, I really like the idea of not having pads generate heat on a carbon wheel, even if it means adding a wee bit of rotational mass. Maybe mental, but it is a great state of mind!

It's very easy to get hung up in weights and aero bits as they do matter but I can also say that I've ridden a bike or two that was thought very highly of in the press while I hated it.

 

Saccon BL for 7 speed down tube shifters and campy Mirage brifters for 8-9 speed set-up.
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I can appreciate your sentiments. However, having some heat is good especially when it's wet as it helps dry the braking surfaces. If you get too much heat it may simply be due to overly aggressive brake pads for those particular wheels.

IMO effective braking depends a lot more on my tires and road surface than my brakes, especially in the wet. I try to find the best tires and maintain optimum tire pressures for the conditions.

 

Thanks for the photos. Mirage brifters came on the market before I replaced my old bike gear and I wasn't paying any attention to bike equipment for some years. It took a while for me to ignore the funny tilted sideways hoods on my Campy SR brifters.

 

Quick question for the far more experienced riders here: what are your experiences with tubeless road setups?

I appreciate the mess and hassle of glue during installation, but are my expectations of a smoother ride, fewer (zero?) flats, and the ability to ride without a crapton of spares realistic? Between CO2, extra tubes, nozzle, and levers, its a lot of junk to drag around. I did my first climbing ride of the season yesterday, and had lots of time to think about it...

 

Do you mean tubeless tires or tubular tires? Two very different things.

 

Tubeless.