this thread is going to be super funny in 5 years.

Oh...I agree it's not overly difficult. It's just additional steps that are the result of making the design decision to make the fork one-sided. Most aren't aware of that. I wasn't.

Don't forget, the mechanic wasn't putting the same wheel back on...it was swapping out to a different wheel, which again, would most likely require a caliper position adjustment after it was rotated back into place and the removed bolt tightened down. I can see how he was trying to avoid that if he could.

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What I think is super funny right now is that there's 5 pages of discussion, and barely anyone has addressed the substance of the first post. It's devolved into the same old "I don't get it" vs. "discs are coming whether you like it or not, so get over it" BS.

Actually, it's more sad than funny...

Edit: Well...upon further review...I take that back. There's actually been some good discussion in the first few pages.

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I officially learned something today!

And it's still early!! :-)

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Tom, you've brought up a lot of great points rebutting many of the reported advantages of disc brakes, however I haven't seen your reply to the possibility of overheating.

About a month ago a friend and I both had tires explode and rims de-laminate on a long, technical, and steep descent in Vermont. I should also mention that we're both rather lean and were not dragging our brakes. I can see only two solutions to this: stop occasionally to let our rims cool, or use disc brakes. I'd love to be wrong and hear option three.

I'll take a lot of the responsibility for that, for interjecting with my two-wheels-same-bike post!

But back to the matter at hand, I don't really think it comes as a big surprise. The main reasons I got started experimenting with road/CX disc about 10-12 years ago wasn't really for improved stopping distances (or at a higher level, to get "better" braking). It was to get to what I considered to be acceptable braking without noise. In other words... try to find a way to get braking on wide-tire bikes that would be as good as standard road rim calipers.

I think a lot of what pushed me to try it was cheap V-brakes, bad cantilever cable stop location (too high) and frames/forks with insufficient stiffness. I had CX bikes with terrible fork shudder... and thought that discs would fix it (but then had the same problem on a disc bike with a really light/crappy fork). I actually ended up with a really nice braking system on a Yeti CX bike with super stiff Alpha Q fork and V-brakes. Nice V-brakes work super well i.e. Shimano XT. I think a lot of people just have had bad experience with cheap stuff and assume that all V-brakes are that way (similar to arguments I've heard against triple cranks... when a person's only experience is on a Shimano Sora triple...).

What happened over time was that discs became almost unavoidable for me. That's how the industry goes. We talk shit about how stupid a technology is, but then later everyone gets scared of missing the bandwagon and then they ALL jump on the bandwagon (27.5" wheels, "Plus" tires, and all manner of axle, bb, and headset "standards"). It's just annoying because we're usually not solving many problems, and often create new ones. Rim brakes aren't the problem. It's poorly executed rim brakes, and frames/forks that don't support them well. And perhaps a lack of education on different pad compounds. There are some good disc brake systems that perform nicely, but I think we need a lot more data to show any sort of general conclusions (for example, take the Tour magazine test and use a bunch of different pad compounds for both brakes, or try some hydraulic rim brakes). For my personal bikes, I'm always going to go with the combination of performance and ease of ownership that best suits me. And I like riding (and sleeping) more than I like wrenching, so I typically err on the simple side, even if it's at the expense of a very marginal gain.

Option 3: Don't use all-carbon rims. You'll get better braking with little to no mass or aero drag increase using wheels with aluminum brake tracks.

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I had a blow out of a latex tube on a really steep descent with aluminum rims. I got stuck behind a car and was forced to use my brakes hard and long, and I had to bail into the grass on the right. That was the last time I used latex on the bike I ride hills with.
Honestly I think aluminum rims heat up more than carbon. I've felt both at the bottom of a descent just to see and I couldn't touch the aluminum rim. They don't delaminate though and I'm sure they cool down fasted too, but they do transfer the heat to the tube. I'm still not ready to try road tubeless yet even though I have been that way on the mtb and cx bikes forever

Tubeless doesn't help with delimitation, but might solve the tube blow out. I'm wondering if anyone has had a tubeless tire blow out on them from a braking-heat related incidence.

FWIW, I'm one of the few guys that actually doesn't have any issues with how my latest set of tubeless full-carbon wheels brake in the dry or wet. But wow did previous generations create some pucker factor waiting for bite in the wet and the incredibly long stopping distances.

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As an aside about the lefty: it's actually pretty easy to change tires and/or throw in a tube with the wheel still on the bike :)

I've owned a few Leftys over the years and have a Scalpel now. It takes me about an extra 30 seconds to loosen the two bolts and slide the caliper off. It's really not that difficult lol

I know...but when I told the mechanic to just throw a tube in there (it was a tubeless tire that was leaking along the beads) he said "We don't have any".

I was all "WTF?" :-/

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I would check the inside of the rim bed for sharp edges...and also maybe consider using a double-layer of tubeless tape as your rim tape (more durable and better insulation).

Carbon rims DO get hotter and retain that heat more (less thermally conductive). That's been shown with measurements. The lower conductivity of the carbon is why they didn't feel as hot. Your hands don't have "temperature sensors" in them, so much as "heat flux sensors". Items that can dump heat into your hands faster (i.e. higher conductivity) will feel much hotter in your hand than lower conductivity items at the same temperature. I actually have to design around this effect often on hand held devices.

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I totally agree with this. The bike that's easiest to work on gets ridden more - especially true for tri bikes.

On the marginal gain part, the extra weight of disc's is more than a marginal loss. Other things equal, on the hill behind my house they cost around 15 seconds (more for most people). On other hills in the area it might even be a minute or more. Who in their right mind would race them? You've got people out there replacing all the little bolts on their bike with titanium to save a fraction of that, and now you want to bolt a dumbbell to your bike for no good reason? Count me out.

It was definitely the heat. I double layer stans tape and never had an issue before that. Same rim tape since many miles later with butyl tube.

Even Cadel Evans had a blowout with a carbon clincher at the end of the race I did last Saturday ;-)

On a straight dry line disc brake and rim brake are equal because braking distance is dictated by the distance from the rider center of gravity to the front wheel and the rider center of gravity height. The only exception would be old single pivot with bad pads that would limit braking. So the "Tour" comparison is moot because they don't understand what they're testing. Beware of Germans, they look serious but they make mistakes too. Also triathlete and time trialists should use bike with longer wheelbase because they don't have to suck a front wheel and it would improve their braking. Always buy the longer bike that fit you for Time Trial.

Disc brake have one big advantage : the braking is quite consistent in wet conditions. Rim braking on a wet rim is scary, and twice scarier on carbon rim. Sometime it'll brake, sometime it won't. Most of the time one need about 20meter to "reactivate" your pad so the braking became efficient. That is the main bad point of rim brake.
That said i'm not that much racing under the rain and on technical course at the same time. Rainy races are below 10% and for triathlete technical races are below 5% i would say. So that make a bonus for some very rare occasions. Sure for training purposes better braking is better but you can also be more cautious on those rainy days, not a big deal. So i'll keep my rim because i have nto unlimited money. If i had i would probably go for it but just don't expect any real gains.

Disc brake on the road have a few other plusses :
My girlfriend like the better braking with less force.
Better feel and modulation (but it won't help you win any races, it's not mtb).
Capable of more convoluted routing.
cleaner.

And obviously one downside :
It's heavier by a good 500gr or more for same spec and about 800gr to 1000gr to same price. Not negligible.

Also for people not used to disc brake a few care thing have to be learned. Never use lube in spray close to your bike, never touch the disc with your hand or a rag or anything. Just let those discs alone.

I always find GT85 brings the rotors up nicely.

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Again, you know that 'get over it' paraphrasing was a joke right. Discs are horses-for-courses, dependent on road & riding conditions.

Seriously though, was there a similar discussion on phasing-out threaded BBs? I really miss the convenience & robustness of BSA68 bottom brackets.

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This ^

Using a single, straight-line, dry weather test as "proof" that rim brakes are equal to disc brakes is nonsense. To use another motorcycle analogy, it reminds of of the ABS vs. non-ABS arugments, and the straight-line, dry weather tests using professional riders that "prove" that you can stop more quickly with a non-ABS motorcycle than an ABS-equipped motorcycle. What people don't like to discuss is that an average rider on an ABS-equipped bike will manage a stop that's at least 90% of max *on the first attempt*, and every single stop will be close to max performance with ABS. Conversely, on a non-ABS bike, it took even the pro's several attempts to get close to the max, and a normal rider's first attempt was horrendously bad vs. ABS, not to mention the likelihood of locking the brakes up in wet weather.

How does this all relate? Disc brakes on bicycles have better modulation, better wet-weather performance, and better fade resistance. All of this adds up to the 'normal' rider being able to execute a near-maximal braking effort *the first time*. You don't get 10 attempts to avoid that SUV that just turned in front of you.

Regardless of what brakes one chooses, the first time you do a near-maximal braking effort should *not* be in an emergency situation. This is an important safety skill all cyclists should practice and master.

So...it doesn't really rain much throughout the year where I live (SoCal), but we do get a fair amount at times during the winter months. Lately, on the rare occasions I've ridden on the road in the rain, if I know the roads are wet or it may be raining while I'm out, I'll grab my disc-equipped gravel bike...but, mostly because it has fenders mounted during that time of year (since it does double-duty as my daily commuter). It's infinitely more comfortable to ride in the rain IMHO if you aren't dealing with road spray coming up off the tires.

Anyway, to set the stage further...I've ridden MTBs for over 30 years, so I fully understand the differences between rim braking and disc brakes in conditions where the rims can get wet (stream crossings, for example) or muddy/dusty. Discs make a fair good of difference in those conditions, mostly by moving the braking surface to an area that's less likely to get wet or dirty while riding.

Now, I've also ridden in the wet an the road quite a bit in my lifetime with rim brakes and am quite aware of how the variables of rim brakes (i.e. pads, braking surface material, etc.) affect things. Just like with riding through a stream on a MTB with rim brakes, there's a bit of a delay while the water on the rim surface is displaced before braking can begin.

So, the first time I rode a disc-equipped road bike in the rain, the strangest thing happened. I was riding along in a moderate rain and the road was completely saturated. The first time I needed to brake from a reasonable speed, I grabbed some lever...and immediately started laughing out loud. Why? Because even with discs, in those conditions there's still a one wheel revolution delay before braking starts...you STILL have that "Oh shit, nothing's happening" moment. So much for the vast difference in wet braking behavior :-/

Now then, why might this be? Well, when riding on the road in a moderate rain, there's still quite a bit of water that ends up on the braking disc, both from the rain (depending on how hard it's coming down) and from road spray, and it still takes a revolution of brake application (at least) before the water is displaced. Oh, and they sure do make a racket after that (probably contamination from road grime and/or oils). Squeal city.

And guess what? IME, even when the water is displaced, once the braking occurs, it's really no better than a well set-up rim brake using KoolStop Salmons on an aluminum braking surface...which is probably a good thing (to prevent accidental wheel lock-up).

BTW, all those things you mention about "better braking with less force, better feel and modulation, and capable on more convoluted routing" are not disc specific. They can all be had with a hydraulic rim setup as well.

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I guess you've missed all of the complaints about press-fit BBs and the like? For example, https://www.bikeradar.com/...ttom-brackets-38220/

Or I guess you missed the push for the threaded T47 variant?
https://www.bicycling.com/...om-bracket-standard/

Or, the myriad of thread-together BB variants to go into press-fit BB areas?

There's a reason my custom bike was built with a BSA68 BB, and I was quite happy to learn my gravel frame was as well before I bought it ;-)

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That's the "common wisdom" and marketing push...but, as the original subject of this thread tends to point to, that's not necessarily a correct generalization.

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