Value of rim brakes...

[fogrider]

Originally Posted by Kontact

I was just looking at Enve, Zipp and Hed products. None of their disc wheels are less expensive than the rim brake versions, so who is it that is making these "special brake treatments" for a premium?


And labor is the most important factor as none of the materials used in CF wheels is any more expensive than the CF itself. So it comes down to development, assembly and final finish work.

pricing does not directly reflect the cost of R and D or the cost of each option on wheels. pricing has to do with price point and marketing.

also, I rode a rim brake bike today and didn't die!

[Kontact]

Originally Posted by fogrider

pricing does not directly reflect the cost of R and D or the cost of each option on wheels. pricing has to do with price point and marketing.

also, I rode a rim brake bike today and didn't die!

I know that, and maybe Colker knows that. But we're talking about how lowered production costs of not having a brake track will lower prices, so I'm playing along until someone can point out which rims they're talking about.

[ChristianWong]

Current setups:
Road bike, aluminum wheels = Rim brake
Gravel/travel/rain bike, aluminum wheels = Rim brake
29+ MTB = Disc (obviously)

Future decision making criteria:
Aluminum wheels, tires <30mm = Rim brake
Tires >30mm = Disc
Regular rain/mud/grime/grit duty = Disc
Carbon wheels = Disc

FWIW, I do think the current DA/Ultegra Di2 Disc setups are aesthetically pleasing (well, not offensive at least). I can't stand the big levers on the rest of the offerings (Sram anything, Shimano mech/hydro, Campy anything).

[Burnette]

Mavic and other cabon rim brake surface selllers offer some with special rim brake track treatments on higher end models but to be clear, carbo an disc brake wheels are and will be at every price point that carbon rim brake wheels are at, so there's nothing there to chew on.

And no, labor isn't the most important metric between the two systems as far as rims. Whatever is saved on one end is spent on another. That's why you see price parity now.

[belopsky]

i like discs on my mountain bike, except for that time i had no rear brake because the mineral oil was leaking..

[Kirk007]

I ride both disc and rim every week on the road. Just picked up on of Clean's castoffs and it will have Paul mini Moto/retro touring or a mix. That will provide some interesting comparisons.

[Mark McM]

Originally Posted by Kontact

If you say so. Doesn't really look like less layup work or materials.

If that's what you think, you haven't been paying much attention to carbon rim technology, particular carbon clincher rims.

The first problem with carbon rim braking was the inconsistent friction of the carbon composite surface. This caused poor modulation, and brake fade from braking heat (carbon doesn't dissipate heat as well as aluminum). Carbon rim makers spent a lot of time developing new brake track surface layers which are added to improve braking.

The next big problem was for carbon clinchers. Unlike tubular rims, clincher sidewallsy have to withstand tire pressures. Under the heat of braking, it was found that many carbon clincher sidewalls would warp and distort. More development work was put into using different resins which could take the heat.

For a disk brake carbon rim, no separate layers have to be added to the sidewalls for the brake track, and it frees designers to us lower temperature resins. This has the potential of lowering the cost of carbon rims (which is good, as it helps offset the higher cost of disc brake systems).

[Mark McM]

Originally Posted by Kontact

I haven't really seen any disc only rims that were drastically different than the rim brake version in any performance way. Brake tracks don't seem to make rims any heavier.

On aluminum rims, this is largely true. Aluminum rim brake rims typically have a thicker walls in the extrusion, use parallel sidewalls, and machine the sidewalls flat. An extrusion die with uniform wall thickness changes in little in unit cost (and probably only saves a handful of grams), there is probably not a lot of advantage in freeing up the design to allow non-parallel sidewalls, and welded rims need some type of sidewall machining operation to clean up the weld seams anyway (if only for aesthetics). So there is probably only a little to be gained with disc brake only rims.

That being said, manufacturers are already making disc brake only aluminum rims, probably just to save a little manufacturing cost.

[ColonelJLloyd]

Originally Posted by Mark McM

That being said, manufacturers are already making disc brake only aluminum rims, probably just to save a little manufacturing cost.

Whatever the reason, my disc specific i23 650b aluminum rims weigh ~341g. An aluminum i23 650b hoop for rim brakes would unlikely weigh much less than 500g. Pretty significant weight savings where it counts. It could very well be that the particular alloy used in these rims isn't suitable for rim brake applications.

[choke]

Originally Posted by fogrider

Would you buy a new bike today with rim brakes?

That's the only type of bike I'd buy....I have no desire to ever own another bike with discs (I once owned a MTB with them). But I also have zero interest in owning a set of carbon wheels as well and like other have said that is a good reason for discs.

Dario had this to say a few years ago: "One of the main functions of disc brakes is to solve the problems of the carbon wheels manufacturers. Solve problems of the wheels is not my job."

[Kontact]

Originally Posted by Mark McM

If that's what you think, you haven't been paying much attention to carbon rim technology, particular carbon clincher rims.

The first problem with carbon rim braking was the inconsistent friction of the carbon composite surface. This caused poor modulation, and brake fade from braking heat (carbon doesn't dissipate heat as well as aluminum). Carbon rim makers spent a lot of time developing new brake track surface layers which are added to improve braking.

The next big problem was for carbon clinchers. Unlike tubular rims, clincher sidewallsy have to withstand tire pressures. Under the heat of braking, it was found that many carbon clincher sidewalls would warp and distort. More development work was put into using different resins which could take the heat.

For a disk brake carbon rim, no separate layers have to be added to the sidewalls for the brake track, and it frees designers to us lower temperature resins. This has the potential of lowering the cost of carbon rims (which is good, as it helps offset the higher cost of disc brake systems).

Again, it isn't that those things aren't happening, just that we aren't receiving a discount when they aren't needed on disc-only wheels.

[Kontact]

Originally Posted by ColonelJLloyd

Whatever the reason, my disc specific i23 650b aluminum rims weigh ~341g. An aluminum i23 650b hoop for rim brakes would unlikely weigh much less than 500g. Pretty significant weight savings where it counts. It could very well be that the particular alloy used in these rims isn't suitable for rim brake applications.

Where did 500g come from? There are tons of rims out there that are for rim brakes and are just as light as their disc cousins. And that's because the material needed for breaking is pretty much the same material needed for the rim's structure.

[colker]

Originally Posted by choke

Dario had this to say a few years ago: "One of the main functions of disc brakes is to solve the problems of the carbon wheels manufacturers. Solve problems of the wheels is not my job."

That´s exactly my point.
It does not matter if discs are better. We had good enough brakes on road bikes before discs came in the equation.
It´s about economy of scale. carbon is the material of choice in the bike industry.
Once there is no heat build up on the rim surface, carbon clinchers seem like a good choice. Then you have tubeless technology. Next Campagnolo decides to forgo tubulars and invest on clincher carbon wheels.
We can always have a custom bike w/ whatever brakes we like but once rims w/ brake tracks are deemed obsolete, everybody will go w/disc brake bikes. And it´s not about the brakes.. it´s about the wheels.

[ColonelJLloyd]

Originally Posted by Kontact

Where did 500g come from? There are tons of rims out there that are for rim brakes and are just as light as their disc cousins. And that's because the material needed for breaking is pretty much the same material needed for the rim's structure.

The 500g came from nowhere specific, just a number that seems plausible given the weights of narrower rim brake hoops I'm used to seeing.

Just use my specific example. I haven't really looked so maybe you're right. What are some weights (published and actual) for aluminum 650b rim brake hoops with an internal width of 23mm? I don't know that I've even come across an i23 650b rim brake hoop.

If a HED Belgium + 650b rim brake hoop weighs 430g and you made it 2-3mm wider I suspect that would add some weight. It might not bring it to 500g, but my point is that disc specific rims can be and are lighter than rim brake hoops with the same internal width. Not really interested in beating this horse much further, though. I don't know why some people have to argue against discs just because they're perfectly happy with their rim brake bikes. I seem to be existing fine with a foot in both camps.

[Kontact]

Originally Posted by ColonelJLloyd

The 500g came from nowhere specific, just a number that seems plausible given the weights of narrower rim brake hoops I'm used to seeing.

Just use my specific example. I haven't really looked so maybe you're right. What are some weights (published and actual) for aluminum 650b rim brake hoops with an internal width of 23mm? I don't know that I've even come across an i23 650b rim brake hoop.

If a HED Belgium + 650b rim brake hoop weighs 430g and you made it 2-3mm wider I suspect that would add some weight. It might not bring it to 500g, but my point is that disc specific rims can be and are lighter than rim brake hoops with the same internal width. Not really interested in beating this horse much further, though. I don't know why some people have to argue against discs just because they're perfectly happy with their rim brake bikes. I seem to be existing fine with a foot in both camps.

The difference between regular 23mm Belgiums and the wider 25mm + version is only 10grams for 700c.