Thanks that was the article I meant. So not adhesive as I remembered wrongly, but aluminium in the center of the sandwich. Anyway, maybe those discs have been improved in the meantime.

Just get any other disc. Most models are one piece of steel with no aluminum in the center.

You’re asking the wrong question. Disc brakes ARE better, it’s your own safety, of course you should go with them. Wether they’re faster or not is irrelevant. Doesn’t matter if anyone is nearby, anything is the issue, animals etc
When that’s said, there’s a small weight penalty. Aero has almost evened out

ecce-homo wrote:

But it seems we, the consumers, are to easy to manipulate.

This points to what I find interesting here. The naivety of the disc supporters - their willingness to believe that the industry's leap to disk brakes for ALL applications is driven by technical purity.
Get real - bike manufacturers are businesses, driven by profit, and I've yet to see an industry that, especially at the high end, isn't looking for a way to render their entire installed product base obsolete, and here it is - disk brakes. Of all the changes in the last 30 years, none of them approaches disk brakes for creating obsolescence. 9/10/11/now 12 speed? You can upgrade with a new cassette, shifter, and chain. All the components of your old frame will work fine with the newest exotic frame material. Electronic shifting, wired or wireless, is a bolt on replacement. New crank configurations work with existing frames. Modularity and standardization have made most of your bike swappable. Not so with disk brakes, though - by requiring new brakes, new wheels, AND a new frame, they've made it a near certainty that, for most consumers, a switch to disc brakes will necessitate replacing enough of the bike necessary to cost justify just replacing the bike.


Disk brakes have their applications, especially for mountain bikes, but tri-bikes represent the highest profit market segment, as people seek ever diminishing returns in shaving off micrograms of weight and aerodynamic gains equivalent to plucking a single hair off a gnat's backside. P.T. Barnum would be impressed.


The bike industry is every bit as susceptible to capture by gimmick and trend based marketing as any other industry. Why else would we have wireless digital shifting? Given the perennial doping scandals in competitive cycling, would you really not expect competitors to eventually hack those systems, and once they have, their methods to trickle down to run of the mill malcontents? Come on, these are the companies that are raking in big bucks selling curve frame retro cruisers with balloon tires to hipsters - what makes you think their conscience kicks in when it comes to the triathlon market? Spinergy wheels, anyone?


I have a titanium frame tri-bike with tension cable shifting (front derailleur isn't even indexed) rim brakes, and innertube clinchers. It's at the point weight- and aero-wise, where realistically speaking, I'll get far more benefit from spending more hours a week training than I will from spending those same hours doing overtime or a side hustle and spending the proceeds on the latest bike tech craze. Odds are, unless you're a 19 year who's maintaining 25mph for hours at a time on a 40 year old Sears' Free Spirit steel touring bike, the same goes for you. If you're a smart consumer, your primary response to tri-bike industry's shift to disk brakes will be to score a great deal on higher-end rim brake wheels than you currently have via the used market.

At races, people notice and remark about my bike. I have them heft it, then I tell them how little I have invested in it. They nod approvingly when they figure out that the price difference between my bike and theirs could pay for a trip to their fantasy dream race.

Toyota still uses rear drum brakes on their coveted (just look at the blue book value of a Tacoma with 100K miles) pickup trucks, because 95% of their braking power comes from the front wheels, and drums are vastly superior for holding a heavy loads in a parking situation, which is the primary role of rear brakes on trucks. Sometimes the traditional tech really is the best choice.


I just don't see any benefits that trump the weight penalties. With the right pads I've gotten sufficient stopping power out of my front rim brake, when it's wet, to lift my rear wheel six inches off the ground. Before disk brakes hit the scene, I remember at least one manufacturer pushing hydraulic rim brakes, so hydraulics, even if they didn't massively multiply failure points, aren't a benefit limited to disc brakes. Some of the "benefits cited make no sense - wider tires? In 50 plus years of building bicycles, I've never seen performance oriented road tires get anything but narrower - does anyone think there's really a revelation to reverse that trend?

Most of the time the interests of people with something to sell you are in direct conflict with your own interests.

Can you please append some of this magical accounting data so I can send it along to some of the other (former) tri bike leads/PMs I know?

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

People around the industry are laughing their asses off at that one. One bike company, which was deep in tri, told me they now sell 9 gravel bikes for every tri/TT bike. So anyone who thinks companies will make rim brake wheels/bikes—which are barely noticeably slower for the bulk of riders—for this segment is living in the past.

 
"Tell us you don't know anything about the bike industry without telling us you don't know anything about the bike industry"

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

On a somewhat related note, my two road bikes are both 160mm/140mm, but when I recently built up my P5D, I went 140mm/140mm. I'm sure there are some riders or use cases where 160mm on the front makes sense, but for the type of riding and racing I do on the TT bike, 140mm up front is plenty.

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Amateur recreational hobbyist cyclist
https://www.strava.com/athletes/337152
https://vimeo.com/user11846099

I think the accuracy of this post goes downhill after the first 12 words. :). (I'm kidding, not kidding, but smiling and not being mean, ok? )

I've never had disc rubbing; nor do all my friends who ride discs. Not sure who rates the shops you are using. Flat mount DB with frame makers that know what they are doing and these issues don't really seem to be happening (unsolvable rubbing, yes DB rubs if not set up properly)on DB bikes released in the past few years.

Weight; ok I'll give RB the grams!
Aero: not always true when viewed from bike/fork/system point of view. Toss up; New wheels are all DB so development means DB will be categorically faster in the future.
Convenience: I like stopping more than the extra seconds it takes to remove a wheel or stick a piece of plastic in between the pads for travel.
Cost: Ever had to replace a RB wheel after the brake channel wore out? I had that happen to a nice set of wheels; expensive!
Pogacar...I'm not as good as him on a bike so a few grams doesn't matter as much to me...but in this year's Tour, he was certainly riding discs on mountain stages; he still seemed pretty fast to me :)

And finally...do you ever need to stop in the rain? No matter how much people love RB for any particular reason, it is indisputable that DB simply stop faster and with better modulation in the wet. I'd say this is a pretty substantial advantage over RB given the primary characteristic that makes a brake good or bad is how quickly, reliably and safely it brings you to a stop. (This is slowtwitch so I get it that others will say no, 0.23 watts at x yaw angle matter more.). And like one poster said, outside NA, there are lots of races with something other than flat topography where a Tri bike is still better, and DB makes it even better/faster because of the technical terrain.

I actually ride both RB and DB and don't hate on RB at all, but I would certainly not argue that disc brakes are inferior, let alone in "pretty much every way" !!

To clarify, highest unit profit margin segment.
It has to be to justify being in that space at such low volume.

Which wasn't the point. Are you just being pedantic or did you mean to say you believe that bike manufacturers would NEVER do something like push disk brakes just to create built in obsolescence of the installed user base?

Bless your heart

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

I'll take that to mean that, as someone whose livelihood is closely coupled with the success of the industry, you plead the 5th on the actual question.

Bless your heart

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Tech writer/support on this here site. FIST school instructor and certified bike fitter. Formerly at Diamondback Bikes, LeMond Fitness, FSA, TiCycles, etc.
Coaching and bike fit - http://source-e.net/ Cyclocross blog - https://crosssports.net/ BJJ instruction - https://ballardbjj.com/

If I can tack an auxiliary question on here: do we have any empirical data on which *size* disc rotors are most aerodynamic, all other things equal?

I guess the assumption is that rotors are inherently un-aerodynamic, so less would be better.

But with wheels it seems a deeper/larger surface allows some aerodynamic benefits. So I wonder.

EP

622mm and 571mm

:)

Like!

this is to the thread in general. i have DB on my gravel bike and it is the only DB bike i have and want to know if my experience is typical. I use 2 wheelsets, one for road and one for gravel. My road set have 30mm tubeless on 303 firecrest and my gravel set are 38mm SS - so at a push i can ride the road set on rough stuff and the gravel set on the road, and i only swap the wheels about every 2 to 4 weeks. Is it unusual for every wheel swap to need a bit of an adjustment? Not usually a lot, but one wheel, usually the front, will almost always need me to go through the routine of realigning the caliper, pushing the pistons back (whether they are out too far or not), and using that silly little tool between the pads. it seems to be a crap shoot whether my attempt to eliminate that annoying little "ping" will make things better or worse. None of this is a deal breaker, and i always get things to work....but is this typical or do i just have 2 front wheels or rotors that are a little more different dimensionally than is usual?

would love to have some disc brake hydraulic equivalent to a barrel adjuster. Brakes just catching - then tweak the pads wider by a fraction of a mm.

otherwise my experience with DB has been very positive. Riding the DB bike on the road has impacted my assessment of how good the brakes are on my rim brake road bike though.

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And the question remains. where were you.

Whether it's typical or not, I cannot answer. Just my +1.

I have one front wheel with a slightly 'faulty' disc brake rotor - it's maybe 0.5-1mm closer to the wheel (but it's even around the whole circle) compared to all other rotors on all other wheel sets. FYI, all rotors are SRAM 160mm and all wheels sets are DT Swiss ARC 1XXX. I simply stopped swapping this one to avoid re-aligning, but I could also just buy a new disc or try to bend it around the whole circle.

Its very common. But there are shims made to fit under the rotor (both 6 bolt and Centerlock), so that you can get all wheels to match. *Very* important when you're dealing with an entire team's bikes, along with lots of spare wheels, and every wheel has to match every bike...

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"I'm thinking of a number between 1 and 10, and I don't know why!"

thank you for the replies. Watching the pro teams just swap wheels without any alignment issues was one of the things that made me question whether i was having to make too many adjustments - but it makes sense that they ensure every one of their wheels have rotors aligned the same.

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And the question remains. where were you.

I didn’t know they existed, thank you.