Carbon wheels and rim brakes...

[XXtwindad]

Hi All -

I might have the opportunity the pull the trigger on a swap for a great rim brake bike. Probably my first and last one. (amazing how they've plummeted in value) Some carbon hoops would be a great pairing with the bike, but I'm still very wary of their performance when used with rim brakes.

I know some of you on the recent "custom build" thread (Jeff N, Flash, enr1co, prototoast) appear to favor carbon hoops, so I'm hopeful there's a consensus that the overheating concerns are an issue of the past.

A little about me if that's germane: I'm a big guy (200 lbs) who lives in an area with very steep hills, and I'm not a downhill bomber. My brakes are used :)

Really thankful for any feedback …

[glepore]

Steep isn't really the issue, long is. And knowing how to brake. Brake hard, release allow to cool brake hard again on long descents. Short rollers, no matter how steep, aren't usually an issue.

The problem hasn't gone away. The better rims use better resin now, but for clinchers this is the single best argument for discs.

[oldpotatoe]

Steep isn't really the issue, long is. And knowing how to brake. Brake hard, release allow to cool brake hard again on long descents. Short rollers, no matter how steep, aren't usually an issue.

The problem hasn't gone away. The better rims use better resin now, but for clinchers this is the single best argument for discs.

Perhaps but the OP has his eyes on a rim brake bike..
Modern carbon rims have less of a problem BUT rim brake and carbon?

Tubulars....:)

[Blue Jays]

Campagnolo Hyperon wheels have been perfectly serviceable in my experience on varying terrain with rim brakes.

[AngryScientist]

depends on the wheels i guess. the new textured brake tracks available, combined with higher temp resins have greatly improved rim brake performance with carbon wheels.

remember, discs are just beginning to take hold, but the pros ride carbon rim brake bikes in all the grand tours, though they are on tubulars, it's not as if they routinely melt their wheels coming through the alps.

as mentioned, knowing how to brake counts for a lot.

[FlashUNC]

I descend Claremont slowly (the seams in the corners just keep getting worse and worse) and regularly on carbon rims with no issues. Same with the top of Pinehurst with those three rather tricky and steep switchbacks.

Modern carbon rims -- especially tubular -- do a really great job of dissipating heat and providing reliable braking on par with alloy rims imo.

[prototoast]

The latest build I posted is with A Force Al33 aluminum rims with the ceramic brake track coating. This build was for my wife who previously had only ridden disc brake bikes, and like the all black look of carbon rims, but I did not think she would be comfortable with the decreased braking power.

As for me, I have carbon rims on one of my rim brake bikes, and aluminum rims on another. Both will get me down Diablo in the middle of summer, but the braking power is noticeably better with the aluminum rims, and my hands are a lot less tired at the bottom.

Overall oh, I find carbon rims fun to scratch that occasional itch, but more often than not I'm happier with aluminum.

EDIT: For reference, the carbon wheels I ride the most are 2017 Mavic Ksyrium Pro Carbon. I have ridden few other carbon rims, including some open mold chinese rims, and some older Bontrager Aeolus. The Mavics brake significantly better than those, but still significantly worse than aluminum. I don't have experience with other premium carbon rims such as Enve, Zipp, Campagnolo.

[echappist]

Perhaps but the OP has his eyes on a rim brake bike..
Modern carbon rims have less of a problem BUT rim brake and carbon?

Tubulars....:)

exactly this

rim brakes and carbon tubulars

or

disc brakes and carbon clinchers

don't do rim brakes and carbon clinchers

Rim brake carbon tubulars are losing popularity. A decent set could be purchased for ~$400-500, though gluing and removing the glue is a PITA

If i could be bothered with riding with a spare tubular, I'd def ride mine more often

[dddd]

I built up a pair of Yoelio carbon hoops for the biggest guy in our club (6'2" and easily 200+), and he put a year of foothills riding on them with nary an issue, including descents of Iowa Hill Rd.
He has since bought a disc-braked Canyon, he likes it but it has by far the noisiest rear drivetrain you've ever heard and no one seems able to diagnose it at roadside (haven't tried swapping any parts).

[Mzilliox]

one more vote for carbon tubulars. lighter and more fuss free than clinchers, plus a better brake track. Boras are my gold standard right now, but my Zipp 303s have been delightful as well. id be all over a set of reynolds something something if i were looking right now as these seem to have great stats at great prices

[glepore]

Perhaps but the OP has his eyes on a rim brake bike..
Modern carbon rims have less of a problem BUT rim brake and carbon?

Tubulars....:)

Yes. Tubulars. All of my carbon wheels are now tubies. I know the op has his eye on a rim brake bike. For a guy of his size, I'd argue against carbon clinchers on long grades. Short grades, sure. Disc brake bike, no issue. But rim brakes + 250 lbs + carbon and long descents are a bad combo.

It also matters whether you're riding alone, in which case you brake as you wish, or in a big event, where you can't. There have been LOTS of reports of failed carbon wheels at events like Levi's, where you can get stuck in a long descent with folks that are constantly checking speed and causing folks to ride the brakes, putting heat into the rims.

[Mark McM]

You mentions carbon rims, but not what type/shape. Are you looking for shallow or deep rims? Wide or narrow? And most importantly: Clincher or tubular?

The last question can be important regarding braking, as there are more complications building a carbon clincher that take the heat of heavy braking. So much so that carbon clincher rims are typically much heavier than carbon tubulars, negating much of the benefits of carbon wheels.

But there is a compromise solution: Hybrid carbon/aluminum clinchers rims, that combines deep carbon fairings with aluminum rim extrusions, and provides the braking performance of aluminum rims with the aerodynamic shape of a carbon rim. This type of wheels can be quite competitive in weight to full carbon clincher rims (and usually quite a bit cheaper). There are several makers of these wheels including HED, Bontrager and Swiss Side.

[echappist]

Perhaps but the OP has his eyes on a rim brake bike..
Modern carbon rims have less of a problem BUT rim brake and carbon?

Tubulars....:)

Yes. Tubulars. All of my carbon wheels are now tubies. I know the op has his eye on a rim brake bike. For a guy of his size, I'd argue against carbon clinchers on long grades. Short grades, sure. Disc brake bike, no issue. But rim brakes + 250 lbs + carbon and long descents are a bad combo.

It also matters whether you're riding alone, in which case you brake as you wish, or in a big event, where you can't. There have been LOTS of reports of failed carbon wheels at events like Levi's, where you can get stuck in a long descent with folks that are constantly checking speed and causing folks to ride the brakes, putting heat into the rims.

yep, +1 to this as well

[XXtwindad]

Really appreciative for the feedback so far. Very helpful. There seems to be almost universal doubt on carbon clinchers for rim brakes. That was enough input for me. So, I will eliminate them from consideration.

[XXtwindad]

The latest build I posted is with A Force Al33 aluminum rims with the ceramic brake track coating. This build was for my wife who previously had only ridden disc brake bikes, and like the all black look of carbon rims, but I did not think she would be comfortable with the decreased braking power.

As for me, I have carbon rims on one of my rim brake bikes, and aluminum rims on another. Both will get me down Diablo in the middle of summer, but the braking power is noticeably better with the aluminum rims, and my hands are a lot less tired at the bottom.

Overall oh, I find carbon rims fun to scratch that occasional itch, but more often than not I'm happier with aluminum.

EDIT: For reference, the carbon wheels I ride the most are 2017 Mavic Ksyrium Pro Carbon. I have ridden few other carbon rims, including some open mold chinese rims, and some older Bontrager Aeolus. The Mavics brake significantly better than those, but still significantly worse than aluminum. I don't have experience with other premium carbon rims such as Enve, Zipp, Campagnolo.

I've never heard of A Force before. This seems like a great solution! How's the braking power? Do the ceramic tracks maintain their color? Aesthetics are an admittedly big issue with this bike. It's very sleek and their alu rim tracks would kinda mar the looks, IMO.

[XXtwindad]

You mentions carbon rims, but not what type/shape. Are you looking for shallow or deep rims? Wide or narrow? And most importantly: Clincher or tubular?

The last question can be important regarding braking, as there are more complications building a carbon clincher that take the heat of heavy braking. So much so that carbon clincher rims are typically much heavier than carbon tubulars, negating much of the benefits of carbon wheels.

But there is a compromise solution: Hybrid carbon/aluminum clinchers rims, that combines deep carbon fairings with aluminum rim extrusions, and provides the braking performance of aluminum rims with the aerodynamic shape of a carbon rim. This type of wheels can be quite competitive in weight to full carbon clincher rims (and usually quite a bit cheaper). There are several makers of these wheels including HED, Bontrager and Swiss Side.

A great compromise. See above.

[XXtwindad]

I descend Claremont slowly (the seams in the corners just keep getting worse and worse) and regularly on carbon rims with no issues. Same with the top of Pinehurst with those three rather tricky and steep switchbacks.

Modern carbon rims -- especially tubular -- do a really great job of dissipating heat and providing reliable braking on par with alloy rims imo.

Claremont is a dicey descent no matter the wheel/brake combo. The shadows really impair visibility. I'd opt for Tunnel every time...

[FlashUNC]

Claremont is a dicey descent no matter the wheel/brake combo. The shadows really impair visibility. I'd opt for Tunnel every time...

Totally. But you can go down Tunnel on a coaster brake if you want. Claremont puts brakes and wheels to work. Pavement on Tunnel isn't getting any better either.

[John H.]

I am going contrary and saying "don't do it".
You are heavy and live where there are hills.
Carbon wheels and rim brakes suck on technical descents, even worse with a bit of moisture.

I always hated carbon wheels and rim brakes- Glad to be done with that and riding carbon disc brake wheels 24/7.

Don't gang up on me- This is only my opinion, and what works for me on primarily on Mt. Tam. Your results may vary.

[XXtwindad]

I am going contrary and saying "don't do it".
You are heavy and live where there are hills.
Carbon wheels and rim brakes suck on technical descents, even worse with a bit of moisture.

I always hated carbon wheels and rim brakes- Glad to be done with that and riding carbon disc brake wheels 24/7.

Don't gang up on me- This is only my opinion, and what works for me on primarily on Mt. Tam. Your results may vary.

You're in good company. Almost everyone here articulated the same opinion. No carbon clinchers for me. Probably not carbon tubs either ...

[dddd]

...EDIT: For reference, the carbon wheels I ride the most are 2017 Mavic Ksyrium Pro Carbon. I have ridden few other carbon rims, including some open mold chinese rims, and some older Bontrager Aeolus. The Mavics brake significantly better than those, but still significantly worse than aluminum. I don't have experience with other premium carbon rims such as Enve, Zipp, Campagnolo.

I had also heard that the Mavic carbon brake surfaces were superior to others, and just bought the same wheels, threw them on five minutes ago, and now to change my pads.

Like Mark mentioned, as a sturdy carbon clincher these aren't the lightest at 1400+(?) grams, but they seem well-made with a quality look all around.
I like the fact that Mavic seems to have pursued higher standards for carbon clincher braking performance instead of rushing their designs to market before the braking met what they considered acceptable braking performance.

As far as using pulsed braking to keep the resins cool, when descending in a crowd of brake-draggers, you can alternate front braking with rear braking in lieu of any brakes-on/brakes-off speed changes.
There is an interesting science to why pulsed braking avoids highest peak temperatures within the rim sidewalls.
I would note that having to pulse the brakes is not something that I would often ever have to worry about, only a couple of places where I ride occasionally (even here in the foothills). I haven't known anyone to blow out a rim around here in many years, seems about as common as alloy rim sidewall failures.

[bigbill]

I'm a fatass and I regularly climb and descent on a set of Boyd carbon clinchers. I use the brake pads Boyd provided and they're tubeless. I had them when I lived in flat east Texas, now I'm in NW Arizona.

[Elefantino]

Have descended Claremont many times on Reynolds carbon clincher rims with CryoBlue pads and ... let me check ... yep, I'm still here, although now on the other coast with mostly rollers and smaller descents.

I also have 50mm carbon Ovals on my Fuji SL, and they stop fine, too. (Although I'm only 180 lbs, give or take.)

For long descents, which are usually preceded by long climbs, I switch out for my AC Sprint 350s anyway. Not because of the aluminum brake track but because they're much lighter and I'm well under the 200 lb weight limit.

[AngryScientist]

i just wanted to mention that you should take any advice from people who have not used carbon wheels in the last decade with a grain of salt.

current generation carbon wheels, both clincher and tubular with textured brake tracks perform remarkably different from older generation wheels.

my fulcrum and bora wheels, in dry conditions stop as well as alloy wheels with the correct brake pads.

caveat: i weigh 130#.

[benb]

I'd wonder what you are getting out of carbon to begin with here.

Are you trying to lose some grams? Is it meaningful?

How fast are you/what is your average speed/are you racing? Does aero matter that much if you're mostly climbing/descending? What percentage of the time are you going full bore at speeds where the aero factors in the rim matter? How often are you doing that alone vs riding in a pack where the aero doesn't matter as much?

It seems like a lot of excuses are being made to make the carbon wheels seem better for your use than they might be. Alternating which brake you use, etc.. is super goofy.

If you have to have carbon for carbon's sake get a disc bike. Or get the tubulars or something. Otherwise why not just get some really nice aluminum wheels? You will probably give up very little in weight that actually matters in the bike + rider equation for a clydesdale rider. And you'll pick up better braking if you're sticking with rim brakes.

[bigbill]

i just wanted to mention that you should take any advice from people who have not used carbon wheels in the last decade with a grain of salt.

current generation carbon wheels, both clincher and tubular with textured brake tracks perform remarkably different from older generation wheels.

my fulcrum and bora wheels, in dry conditions stop as well as alloy wheels with the correct brake pads.

caveat: i weigh 130#.

True, I have a set of "Colnago" carbon tubulars from 2002. Record hubs with rims that were likely Ambrosio with absolutely no brake track. I used them in time trials and the occasional criterium, places where I wasn't expected to brake because they didn't stop.

[mcteague]

And yet another issue to think about with carbon clinchers...sudden blowouts.

https://www.velonews.com/2019/09/bikes-and-tech/technical-faq-a-tubeless-tire-blowout-in-the-pyrenees_500757

It sounds like the rim’s bead hooks cut enough of the threads in your tire casing that it blew. I had never seen this with aluminum rims. However, it has happened to me on multiple occasions on carbon clincher rims with handmade open tubular clinchers (explained here, or here as “handmade clinchers”) with inner tubes. Having such fine treads and a casing that is not vulcanized, handmade open tubular clincher tires are the canary in the coal mine of this issue I’m about to discuss with carbon clincher rims.


Tim

[glepore]

I've never heard of A Force before. This seems like a great solution! How's the braking power? Do the ceramic tracks maintain their color? Aesthetics are an admittedly big issue with this bike. It's very sleek and their alu rim tracks would kinda mar the looks, IMO.

Both the Aforce and the similar wheel from Boyds are really nice.. The tracks are very durable with the right pads. They will eventually wear, but not rapidly. The one caveat is that they do use up pads more quickly than some other surfaces. I use campy red carbon pads with my Aforce wheels and am happy with the combo.

[prototoast]

And yet another issue to think about with carbon clinchers...sudden blowouts.

https://www.velonews.com/2019/09/bikes-and-tech/technical-faq-a-tubeless-tire-blowout-in-the-pyrenees_500757

It sounds like the rim’s bead hooks cut enough of the threads in your tire casing that it blew. I had never seen this with aluminum rims. However, it has happened to me on multiple occasions on carbon clincher rims with handmade open tubular clinchers (explained here, or here as “handmade clinchers”) with inner tubes. Having such fine treads and a casing that is not vulcanized, handmade open tubular clincher tires are the canary in the coal mine of this issue I’m about to discuss with carbon clincher rims.


Tim

On a ride earlier this summer, I encountered a gentleman who had a similar problem (tire separated from bead) on the same tires (GP 5000s) while riding aluminum rims. I can't say that carbon rims wouldn't amplify this risk, but I wouldn't rule out that the tire shares some blame in it too.

[benb]

The Zinn & Rene Herse articles about hookless road/gravel rims and expensive rims that don't meet ETRTO standards kind of blow me away. (LOL)

Going to be looking very closely at the next set of rims I buy. I have no hookless rims, including my Tubeless (UST) mountain bike setup. The UST setup has been safe for > 10 years now. I think hookless beads are going to be an automatic deal breaker next time I'm shopping. I bought some Mavic wheels in 2016 or 2017 while still being ignorant of this but they are hooked road wheels intended for use with tubes so I'm good.

I feel like reading these stories I'd have to be on crack to buy a set of ENVE wheels or fool around with hookless rims at higher pressures... there is just no way if you're not making a living racing bike that there is any performance benefit of any of these carbon clincher type wheels that can justify a reduced margin of safety.

You start reading between the lines and it's immediately clear why the Pro Peloton sticks with Tubulars! They're the only ones where any performance benefit of carbon wheels actually matters and they need to stay safe too.

Crazy that it's all zillion dollar stuff that's sketchy too, and the goal is simplifying manufacturing and making manufacturing costs cheaper. (Cause sanding sharp edges on hooked sidewalls requires human labor & inspection)

I get the hookless rims make it easier to make carbon MTB rims that withstand bottoming out better. Basic physics. I don't understand the physics of how they're supposed to retain the tire safely.. some of the articles mention relying on sealant to act as a glue, but it can't be allowed to dry out. Again.. doesn't sound worth it for the supposed benefits of having carbon rims.

[dem]

Last season I encountered two riders with melted rim brake carbon clinchers at the bottom of steep descents (Mt. Umunhum/Hicks and back side of Mt Hamilton.) One was a brand new set of deep ENVEs.

Yes all the caveats apply about braking appropriately, etc. But that's enough of a sample size for me.

[XXtwindad]

Last season I encountered two riders with melted rim brake carbon clinchers at the bottom of steep descents (Mt. Umunhum/Hicks and back side of Mt Hamilton.) One was a brand new set of deep ENVEs.

Yes all the caveats apply about braking appropriately, etc. But that's enough of a sample size for me.

Umunhum and Diablo are the two descents that came to mind when I started the thread. Points taken. Too bad alu rim strips are so ugly.

[Mark McM]

Umunhum and Diablo are the two descents that came to mind when I started the thread. Points taken. Too bad alu rim strips are so ugly.

The HED Jet Black series wheels are hybrid carbon/aluminum rims, whose aluminum brake tracks have their proprietary Turbine Braking Technology surface treatment (texture pattern machined into the rim, which is then coated with a durable black anodization) which improves braking significantly in both wet and dry conditions. And as the name implies, they are completely black (except for the labels, which can be removed).

https://bikerumor-wpengine.netdna-ssl.com/wp-content/uploads/2014/09/2015-HED-Jet-Black-Ardennes-road-bike-wheels01-600x399.jpg

[prototoast]

The HED Jet Black series wheels are hybrid carbon/aluminum rims, whose aluminum brake tracks have their proprietary Turbine Braking Technology surface treatment (texture pattern machined into the rim, which is then coated with a durable black anodization) which improves braking significantly in both wet and dry conditions. And as the name implies, they are completely black (except for the labels, which can be removed).

https://bikerumor-wpengine.netdna-ssl.com/wp-content/uploads/2014/09/2015-HED-Jet-Black-Ardennes-road-bike-wheels01-600x399.jpg

I haven't used those particular rims, but I had the HED Belgium rims with the dark brake track, and that lasted about 500 miles before largely wearing off.

[Mark McM]

I haven't used those particular rims, but I had the HED Belgium rims with the dark brake track, and that lasted about 500 miles before largely wearing off.

HED Belgium rims are available as rims only, and are not part of the HED's Black series. Your Belgium rims likely just had anodized brake tracks, and as indicated anodization does quickly wear way. The special HED's Black rim treatment (called Turbine Braking Technology) is only available on completely wheels, and is not just simple anodize coating. The Black series brake track treatment has developed a reputation as being quite durable. This was discussed in a previous thread:

https://forums.thepaceline.net/showthread.php?t=228877

[dddd]

It seems like a lot of excuses are being made to make the carbon wheels seem better for your use than they might be. Alternating which brake you use, etc.. is super goofy...

The question seemed to come up of how to deal with the very rare instance of a perhaps heavyweight rider doing a once-in-a-lifetime "fondo" type of event which just happened to include an unusually long, steep descent.
I've never seen anything like this in my years of riding, but am reminded of the years when I (@150#) had a tubular front tire arrive home from a ride with the valve stem suddenly cocked solidly sideways, and of other's more recent (as in like 10-15 years ago) instances of melted 1st-gen Reynolds carbon clincher wheels on our worst-case hills here.

All brakes get hot, and the wisdom over the years is that in worst-case situations, that pulsing the brakes versus continuous smooth braking is less likely to cause braking components to overheat. I believe that this is in part due to the highly non-linear rate of cooling of a surface of a brake rotor or rim in response to varying temperature, and in part to the also non-linear rate of energy dissipation at the tire(s) in response to braking force.
So call this theoretical if you like, but alternating the use of front and rear brakes might be expected to reduce peak temperatures of components in any braking system.

Truth is, as I mentioned in my post, today's carbon rims are not failing with much frequency under even severe conditions.

Among current carbon wheels,some are probably much more within their safe temperature range than others, which doesn't even seem to come up as a purchasing variable any more (because of the infrequency of current carbon rims failing?). Hopefully, some lab testing and publishing gets done on current offerings.

It might eventually be more prudent to worry about the boiling of brake fluid in our current disc brake calipers after a few years worth of moisture has inevitably become absorbed into the fluid.

It could also be that, since bicycle disc brakes sprang from quite-mature technologies coming from the ultra-billion-dollar transportation industries, bicycle rim brakes might improve faster than disc brakes over the next few years.

[Dave]

If you're not racing, what's the point in spending big bucks on carbon rims? I ride a lot of steep hills and some winding mountain roads. I was recently thinking of upgrading to a Campy Shamal aluminum rim wheelset, but with Zondas at less than half the price, I decided it was a stupid purchase. Carbon rim wheelsets are usually far higher priced than Shamals, so you're looking at really big bucks and potential problems.

I guess I'm lucky that all the hills that I ride have good road conditions, so I can descend at up to 54 mph and not need to brake. Weighing only 140 helps too. When I do ride a twisty that requires some braking, it's brief, just before each turn.

[glepore]

OP making a wise choice. A front blowout on a clincher downhill is often a faceplant.

[FlashUNC]

OP making a wise choice. A front blowout on a clincher downhill is often a faceplant.

Anybody dragging the front that much to cook a tire needs to not be riding a bike at all.

[Gummee]

I built up a pair of Yoelio carbon hoops for the biggest guy in our club (6'2" and easily 200+), and he put a year of foothills riding on them with nary an issue, including descents of Iowa Hill Rd.
He has since bought a disc-braked Canyon, he likes it but it has by far the noisiest rear drivetrain you've ever heard and no one seems able to diagnose it at roadside (haven't tried swapping any parts).

If it's D/A, they just seem to run noisy

AFA rim brakes and such... I happen to have a set of 303 tubulars I need to sell. I think they're posted in the classifieds.

M

[dem]

It might eventually be more prudent to worry about the boiling of brake fluid in our current disc brake calipers after a few years worth of moisture has inevitably become absorbed into the fluid.


Shimano uses mineral oil, so does not have this issue. SRAM still uses DOT fluid, but who rides SRAM!?!? :)

[robertbb]

If you're not racing, what's the point in spending big bucks on carbon rims? I ride a lot of steep hills and some winding mountain roads. I was recently thinking of upgrading to a Campy Shamal aluminum rim wheelset, but with Zondas at less than half the price, I decided it was a stupid purchase. Carbon rim wheelsets are usually far higher priced than Shamals, so you're looking at really big bucks and potential problems.

I guess I'm lucky that all the hills that I ride have good road conditions, so I can descend at up to 54 mph and not need to brake. Weighing only 140 helps too. When I do ride a twisty that requires some braking, it's brief, just before each turn.

Good choice. Having owned and extensively ridden Zonda's and Shamals (both C17's, both clinchers (as opposed to the 2-way fit), and both with standard aluminium brake tracks) I decided the Zonda's were superior.

The Shamals have super fat spokes (and nipples) and they catch the wind a lot. This is especially true in a cross wind (can make the bike harder to handle, particularly for a light rider) and I found it also affects the "top end" speed of the wheels as well: the Shamals seem to "top out" at a certain speed, like some kind of built-in terminal velocity, after which they just plod along. The Zonda's feel like they had more to give speed-wise, provided my legs did!

The measured weight difference on my kitchen scales was 65 grams (a significant portion of which will be in the hub... carbon shell bonded to alloy flanges on the Shamal, vs all-alloy on the Zonda).

Looking around the interwebs, testing by tour magazine backed up my anecdotal experience, finding the Zonda's more aero than Shamals and interestingly; slightly stiffer as well.

From a lot of the reading I've done (the wheelbuilders in here may chime in) triplet-spoked rear wheels tend to be far stiffer than your standard-built wheels.

If Campy made a souped-up mille version of the Zonda with an upgraded hub and cult bearings... Zonda+... it'd be heaven.

[fogrider]

Have descended Claremont many times on Reynolds carbon clincher rims with CryoBlue pads and ... let me check ... yep, I'm still here, although now on the other coast with mostly rollers and smaller descents.

I also have 50mm carbon Ovals on my Fuji SL, and they stop fine, too. (Although I'm only 180 lbs, give or take.)

For long descents, which are usually preceded by long climbs, I switch out for my AC Sprint 350s anyway. Not because of the aluminum brake track but because they're much lighter and I'm well under the 200 lb weight limit.

I'm SF and do most of my riding in Marin and SF just to get to Marin. I agree the Reynolds CryoBlue pads are great! They also came out with the Power CryoBlue pads and they are claimed to be 33 percent better...and I pretty much can confirm that!

That said, lightweight aero tubulars are amazing! lightweight wheels just makes a bike feel quick and responsive. and aero wheels = speed...not just top end speed, overall average speed is up. I do have alu rims, but more and more, I'm on the carbon rims!

[enr1co]

As for me, I have carbon rims on one of my rim brake bikes, and aluminum rims on another. Both will get me down Diablo in the middle of summer, but the braking power is noticeably better with the aluminum rims, and my hands are a lot less tired at the bottom.

Overall oh, I find carbon rims fun to scratch that occasional itch, but more often than not I'm happier with aluminum.

EDIT: For reference, the carbon wheels I ride the most are 2017 Mavic Ksyrium Pro Carbon. I have ridden few other carbon rims, including some open mold chinese rims, and some older Bontrager Aeolus. The Mavics brake significantly better than those, but still significantly worse than aluminum. I don't have experience with other premium carbon rims such as Enve, Zipp, Campagnolo.


I also had good experience with a set of 2017 Mavic Ksyrium Pro Carbons. Brought a set to the Alps last year and had no issues or concerns with controlling speed or overheating on longer distance descents and switchbacks relative to anything found in the Bay Area. Would concur with other comments that proper braking technique or not dragging brakes would alleviate concerns with overheating and hand fatigue.

Have ridden Zipps, Enves 3.4, Campy Boras and the Ksyrium Pro Carbons-all clinchers. Would say that the most efficient braking experienced was with the Bora Ones and Campy red pads. Had used Williams blue pads (perhaps same OEM as Reynolds blue?) with the Ksyrium Pro Carbons and also stopped well. Enves with their grey pads have also worked well but have found Campy red pads to have the most stopping power with the limited selection of wheels experienced.

For reference, I'm currently heavier than ever at ~185 :eek:

I don't plan on hitting the 200 lb mark but if by chance I ever do, I'll still have preference to carbon wheels as I dont feel any stopping disadvatage from AL, find them more compliant and lastly prefer the aesthetic :)

[572cv]

A little late to the flow of this thread. Not mentioned so far, I think,, but I’ve been consistently impressed with my dura ace c24s. The hybrid alu brake track/carbon rim works nicely they feel sprightly on the road, the hubs are the proverbial butter smooth, and they have been durable and stayed true. These might be at the edge of the weight limit for the OP, but worth consideration amongst the other good suggestions, methinks.

[Hilltopperny]

I have tried a few rim brake carbon wheelsets at 200-230lbs. Even with textured brake tracks they seemed sketchy for me. With the amount of speed I get on descents I felt the braking was sub optimal even in the dry weather.

I am giving a set of carbon tubulars a shot soon, but I do not expect to have the same braking performance as my exalith surfaced aluminum wheels or even my belgium+ rim brakes. Just a reality when dealing with carbon rim brake surfaces.

The only carbon clinchers I have kept in rotation over the years are disk brake. I have a tendency to get caught in the rain at times. It only took one ride in the rain with rim brake carbon hoops to realize that it was super unsafe at my weight.
Sent from my LGL423DL using Tapatalk

[Hellgate]

It's hard to beat Campy Bora's with red pads.

Good deals are appearing for Bora's too.

[Mark McM]

From a lot of the reading I've done (the wheelbuilders in here may chime in) triplet-spoked rear wheels tend to be far stiffer than your standard-built wheels.

In many cases, triplet laced rear wheels will actually be less stiff. The left (non-driveside) spokes add more stiffness to a rear wheel than the right (driveside) spokes due to have a wider bracing angle. Removing left spokes will only decrease stiffness, even if the same number of spokes are added to the right. Triplet lacing isn't done for stiffness, it is done for durability, because it better balances left/right spoke tension.

[benb]

I have tried a few rim brake carbon wheelsets at 200-230lbs. Even with textured brake tracks they seemed sketchy for me. With the amount of speed I get on descents I felt the braking was sub optimal even in the dry weather.



I'm a good bit lighter more like 175 and feeling overweight a bit right now.. but still on the bigger side.

The thing that I've repeatedly seen that warns me off is being in a group and something happens where the whole group needs to slow dow or stop in a hurry. Like a car dangerously pulling out. Luckily I've never been in a situation where anyone crashed hard in a situation like that. But what I have seen repeatedly is in a normal situation everyone can stop in similar distance so everyone holds their position in the group as the group slows.. but you will see guys on carbon wheels with rim brakes be unable to slow down as fast as the rest of the group so they're unable to hold their position and they shoot forward to the front of the group or even out of the group. In the worst case I remember the whole group easily stopped with 25-30ft or more before the offending car except for one guy on carbon rims + rim brakes who had so much less brake power that he stopped about 5ft short of the car. This has pretty much always occurred in dry conditions where everyone should have their best brake performance available.

I will just always take the best braking available to me.. you would never hear sports car or motorcycle or MTB guys ever talking about whether a slight reduction in wheel weight or aerodynamics was worth compromising brake performance. Roadies are the only ones who will go there.

[windsurfer]

Anybody dragging the front that much to cook a tire needs to not be riding a bike at all.

I live on the top of a long 18-24% grade which includes loose gravel, bad pavement, and a stop sign at the bottom. To get down safely I drag the brakes enough that both (Aluminum) rims are quite hot by the time I reach the bottom.

Guess I shouldn't be riding a bike :no:

[benb]

I live on the top of a long 18-24% grade which includes loose gravel, bad pavement, and a stop sign at the bottom. To get down safely I drag the brakes enough that both (Aluminum) rims are quite hot by the time I reach the bottom.

Guess I shouldn't be riding a bike :no:

There's a ton of cognitive dissonance on this from riders who live in different areas or countries.

I know roads (that I sadly don't ride as much as I used to) where it's extremely hard to get down the road safely without badly fading a rim brake/aluminum rim setup. Sustained average grades > 10% for > 1 mile with frequent switchbacks are just very very tough on brakes. A lot of these roads you can't let the bike run up to 40mph and cool off and then slam on the brakes as per proper technique. Try that on the rougher sections and you'll bounce your rear wheel up in the air over a bump, road bikes with their drop bars don't allow you to get far enough behind the saddle for max safety. The switchbacks just come too frequently and there are too many bumps & frost heaves. Plenty of these roads ban bicycles and/or road bikes now too, they are precious climbs to get on before they get closed off. Mt. Washington would have been a hell of a lot more of an adventure if there was a way to just go ride up and down it on your own without the hoopla of the race and having to take a car back down.

I think this dissonance comes in when people doubt the superiority of disc brakes too.

Some regions of the country are obviously much flatter, if you stick in suburban areas you don't run into that many of these roads. Most of these roads I have experienced this on are summit roads that require paying a toll to the US park service or a private company maintaining a road. My experience has been in areas of the country where roads/civilization are newer you are much less likely to see these roads because the traffic engineers/US Army Corps of engineers was a thing by that point and they engineered a much safer road where they had to build a road at altitude. Maybe Europe has these roads. All of the New England states have plenty of them cause the roads were often built prior to cars being invented.

The fact that a road is covered in pavement doesn't always mean a drop bar bike is the best bike to go up and down the road on.

Now the nice thing is if you really want Carbon wheels and you ride these kind of roads at least today you can get a Carbon wheel setup with disc brakes... assuming those brakes work really well it'll be safer & a lot less stressful than any rim brake road bike.

[XXtwindad]

There's a ton of cognitive dissonance on this from riders who live in different areas or countries.

I know roads (that I sadly don't ride as much as I used to) where it's extremely hard to get down the road safely without badly fading a rim brake/aluminum rim setup. Sustained average grades > 10% for > 1 mile with frequent switchbacks are just very very tough on brakes. A lot of these roads you can't let the bike run up to 40mph and cool off and then slam on the brakes as per proper technique. Try that on the rougher sections and you'll bounce your rear wheel up in the air over a bump, road bikes with their drop bars don't allow you to get far enough behind the saddle for max safety. The switchbacks just come too frequently and there are too many bumps & frost heaves. Plenty of these roads ban bicycles and/or road bikes now too, they are precious climbs to get on before they get closed off. Mt. Washington would have been a hell of a lot more of an adventure if there was a way to just go ride up and down it on your own without the hoopla of the race and having to take a car back down.

I think this dissonance comes in when people doubt the superiority of disc brakes too.

Some regions of the country are obviously much flatter, if you stick in suburban areas you don't run into that many of these roads. Most of these roads I have experienced this on are summit roads that require paying a toll to the US park service or a private company maintaining a road. My experience has been in areas of the country where roads/civilization are newer you are much less likely to see these roads because the traffic engineers/US Army Corps of engineers was a thing by that point and they engineered a much safer road where they had to build a road at altitude. Maybe Europe has these roads. All of the New England states have plenty of them cause the roads were often built prior to cars being invented.

The fact that a road is covered in pavement doesn't always mean a drop bar bike is the best bike to go up and down the road on.

Now the nice thing is if you really want Carbon wheels and you ride these kind of roads at least today you can get a Carbon wheel setup with disc brakes... assuming those brakes work really well it'll be safer & a lot less stressful than any rim brake road bike.

Very thoughtful response, as per usual. Actually, you just did a "mitzvah." I really don't know what I was thinking. I was probably hood winked by the frame's good looks. I usually ride solo. And when I ride with friends, it's social rides, focused on friendship and not speed. Up steep hills, and then down them.

So what do I need a sleek carbon rim brake race bike for? I don't actually.

Thanks, Ben.

[simonov]

Very thoughtful response, as per usual. Actually, you just did a "mitzvah." I really don't know what I was thinking. I was probably hood winked by the frame's good looks. I usually ride solo. And when I ride with friends, it's social rides, focused on friendship and not speed. Up steep hills, and then down them.

So what do I need a sleek carbon rim brake race bike for? I don't actually.

Thanks, Ben.

Agreed. I live in a flat area and regular use campy/fulcrum and mavic carbon clinchers and they're amazing. The braking is orders of magnitude better than Reynolds/Easton/Zipps of yore. They're almost as good as my exalith rimmed aluminum wheels. But in the mountains, I only ride aluminum because having the better braking is a real advantage. You go up and down hills, stick to aluminum. There are some excellent options out there.

[katematt]

FWIW I have a set of Roval c40's and the braking done right seems fine, wet or otherwise and I ride some pretty steep hills that require quick braking from 30ish mph. What I can't stand is the interface between pad and rim vs. Aluminum, just seems like a low grade finger nail on a chalk board. Although every time I check the surface post ride it looks intact and all good.

So I just put up with the noise.

[FlashUNC]

I live on the top of a long 18-24% grade which includes loose gravel, bad pavement, and a stop sign at the bottom. To get down safely I drag the brakes enough that both (Aluminum) rims are quite hot by the time I reach the bottom.

Guess I shouldn't be riding a bike :no:

That means every ride ends with a 20%-ish grade climb home? Time to move.

[windsurfer]

you got it -The last section of every ride is a 24% grade that I have to sweep regularly to assure sufficient traction.

Not planning on moving; Increased power and fitness is the price I pay for a great view

[Mark McM]

I know roads (that I sadly don't ride as much as I used to) where it's extremely hard to get down the road safely without badly fading a rim brake/aluminum rim setup. Sustained average grades > 10% for > 1 mile with frequent switchbacks are just very very tough on brakes. A lot of these roads you can't let the bike run up to 40mph and cool off and then slam on the brakes as per proper technique. Try that on the rougher sections and you'll bounce your rear wheel up in the air over a bump, road bikes with their drop bars don't allow you to get far enough behind the saddle for max safety. The switchbacks just come too frequently and there are too many bumps & frost heaves. Plenty of these roads ban bicycles and/or road bikes now too, they are precious climbs to get on before they get closed off. Mt. Washington would have been a hell of a lot more of an adventure if there was a way to just go ride up and down it on your own without the hoopla of the race and having to take a car back down.

I think with proper technique, some of the roads you talk about are still quite doable with rim brakes. Sadly, there aren't many of these roads were I live in southern New England, but I still do some of them when I visit the mountains. I'd always heard stories about brake fade and tire blow-offs caused by overheating brakes, so when I started doing steep twisty descents I was wary of the possibility. But then I descended Mt. Ascutney (at 2300' in 3.7 miles it is literally half of Mt. Washington - half the distance, half the vertical gain, and same average 11.7% grade ). This descent is on a narrow road completely below treeline, with many blind switch backs. Because it has 2 way traffic you can't use the whole road when going around the blind switchbacks lest someone is going the other way. Nonethless, I let the bike run between switchbacks and braked hard before entering the switchbacks. I was riding very lightweight aluminum rims (plus narrow tires) with rim brakes, and as soon as I reached the bottom, I braked hard to a complete stop and immediately felt my rims to see how hot they were. They were definitely quite warm to the touch, but not super hot (not enough to burn my skin, anyway). I hadn't experienced any meaningful brake fade during the descent.

To be fair, I'm not particularly heavy (racing weight about 145 lb), and most of my climbing/descending is in high density air (lower altitudes) where there is more air drag. But I've yet to experience any brake related problems with rim brakes on long steep descents. Given the number of descents in the alps that are as steep and long or longer that are often ridden by bike, many other people are also doing just fine. (Note: Larger riders and tandems may be a different story. But tandem riders have been finding solutions to the braking problem for decades.)

[benb]

It's been at least 10 years since I did Ascutney. The last time I did it was one of the hill climb races and descending after the race was no longer allowed. In any case I have descended Ascutney quite a few times. I would say Ascutney is/was in better shape than a lot of the other mountain roads, or at least it has been IME. It's a bit more open, a bit easier to let the bike run, a bit less potholed/frost heaved. I never experienced fade there. Maybe Vermont is just better about maintaining those roads? Ascutney gets a lot of activity.. there's a car race, the hang glider crowd is there a lot, etc..

I've never gotten to ride down Mt. Washington, I drove it once this year and it was actually in great shape. I think if you were smart and the weather was good it might be safe for a good rider in good weather with rim brakes. But there is plenty of dirt & dust on Mt. Washington that's going to get on your rims, and just cause it's sunny when you started up you'd have near 0 guarantee you weren't going to get rained on and then it'd get really dangerous really fast. Both times I did the race it started sunny & nice at the bottom but then there was precipitation on the way up.

The worst one for brake fade IME has been Pack Monadnock. I did that one last season but not this year, the road conditions were very tough. I've done that mountain more times than I remember, the road conditions are a major factor in whether you encounter fade. Pack Monadnock in the rain I walked the bike down most of the summit road. It was WAY too dangerous with rim brakes. (I've done it in the wet and with some snow on the road on a MTB and it was fine, wet on a motorcycle it was fine, the thing there was disc brakes.)

I've done some of the passes in the White Mountain National Park when the roads were closed to cars and there was occasional snow. I did that on Standard rim brakes and I was OK, but those were not conditions that let you run the bike to maximum speed to preserve the brakes.

Hurricane Mountain road over the NH/Maine border.. I think that one I may have experienced a little fade. That was a long time ago. Manageable though.

Appalachian Gap up in VT... it was always chronically dusty. I've rode that one more times than I remember both road bikes & motorcycles, but again haven't been there in years now. The dust was very scary on a motorcycle. On a bicycle hard to say.. but that dust was probably getting on your rims. Luckily the road was always pretty smooth and there were pretty good straight sections to let the brakes cool.

Whatever setup you've got, it performs the best it can in particular conditions. Which include the rider not being too heavy, the bike not being too heavy, the conditions need to be dry and not dusty. Not wet, not grimy roads that coat your rims.

Any of the variables start changing away from ideal and you really want to maximize your advantages in the situation... no one here is trying to say Carbon outbrakes aluminum... what would you rather have if you can't control all the variables? Keep the Carbon rim brake wheels in the flatlands where the aero advantages might mean something.

Brake fade is somewhat academic.. even if you start to get it you can manage it if you keep your wits. It's only dangerous if you panic.

[Mark McM]

I've heard stories that many years ago, bicycles used to be allowed on the Mt. Washington Auto Road (up and down), but I haven't seen any information whether that's really true (although I met a few people who claim they've "banditted" the Auto Road by riding it in the middle of the night on MTBs with lights). Recently, the only time that bikes were officially allowed to ride down the Mt. Washington Auto Road was in the Pork Gulch Classic Stage Race (https://www.bikereg.com/3499#Notes), which used the first 2 miles of the road as an uphill TT. When I first raced the Mt. Washington Hill Climb, the road was only about half paved. When I did it this year, the road was about 80% paved.

Pack Monadnock is definitely one of the worst. It isn't as long as Ascutney or Washington, but it is about the same average grade, and when I've ridden it the pavement was in very bad condition. The surface was so bad that you couldn't let the bike run much at all, and you're always on your brakes. I haven't done it in the rain, and I don't think I want to.

I've done Hurricane Mountain Road a few times. I never experienced fade or other braking problems - even when the presence of slow moving cars ahead required me to brake more and go slower than I would have liked to.

I rode App Gap quite a few years ago, but I don't remember any issues with either the road or my brakes.

I haven't done many of these steep descents in the rain, but the worst I recall was Smuggler's Notch in a cold down pour. That was miserable, but more so for the cold rain, and the main braking problem was hands cramping from the cold.

[robertbb]

Whatever setup you've got, it performs the best it can in particular conditions. Which include the rider not being too heavy, the bike not being too heavy, the conditions need to be dry and not dusty. Not wet, not grimy roads that coat your rims.

Any of the variables start changing away from ideal and you really want to maximize your advantages in the situation... no one here is trying to say Carbon outbrakes aluminum... what would you rather have if you can't control all the variables? Keep the Carbon rim brake wheels in the flatlands where the aero advantages might mean something.

This really is an astute comment. Particularly because weather in the mountains is typically the most unpredictable, the most changeable and often the most extreme (hot/cold, wet/dry and everything in between... often on the same day!).

[Dekonick]

This really is an astute comment. Particularly because weather in the mountains is typically the most unpredictable, the most changeable and often the most extreme (hot/cold, wet/dry and everything in between... often on the same day!).

I would rather have a few more grams than test the safety threshold.

[adrien]

I'm 217, bike's another 17 pounds or so.

After many different trials, I got a set of Enve 4.5s. These are the non-tubeless, "hooked" rims.

Riding around Washington DC, in Vermont and Southern Quebec, they've been exceptional. After 15,000 miles they show very little wear.

The key is technique. I never drag brakes, and on longer descents alternate front and rear braking, with a big grab on each. A point worth considering in technique -- they seem to rely more on clamping force to stop than they do on the friction of the pad. So a "big grab" has a bigger effect than simply being a multiple of a lighter pull where you are "dragging" the brake more. I only ever changed to aluminum for one descent, and honestly, I don't think I needed to.

That said, they are not for folks who are new to the sport, don't have the technique or live in very hilly areas. If I lived in say, the rockies, my aluminum rims would get much more miles...

[Mark McM]

The key is technique. I never drag brakes, and on longer descents alternate front and rear braking, with a big grab on each. A point worth considering in technique -- they seem to rely more on clamping force to stop than they do on the friction of the pad. So a "big grab" has a bigger effect than simply being a multiple of a lighter pull where you are "dragging" the brake more.

I agree with the practice of limiting speed by braking hard but infrequently. This method maximizes energy dissipation from air resistance. However - while I've often heard the idea of alternating the brakes, I don't think it is a good idea. In fact, in some cases it may be a bad idea. When you apply both brakes, each brake absorbs half the heat. But when you apply a single brake, you concentrate all the heat on that one brake. The result is that each brake heats up less often, but to a higher temperature. Using both brakes simultaneously may keep them both below the critical temperature (which may be the blow-off pressure, the glue melting pressure, or the carbon glass transition temperature). Using a single brake at a time may periodically raise that brake above the critical temperature.

Also - brakes work by using friction to convert the energy of motion into heat. A "big grab" does not use clamping force instead of friction (heat) - it just increases friction (and thus amplifies the rate the rate of heat generation).

[robertbb]

Saw a 2018 Campagnolo Bora hub for sale on Gumtree, and msg'd the seller out of curiosity.

Clincher wheel that deformed on a descent. This flys against what I've read about Campy wheels being somewhat better built and more resilient to this stuff. Has me seriously re-thinking my own Bora Clinchers as a performance set - maybe better as a "bling" set on a custom bike for flattish latte rides.

Anyway, found this video of a guy here in Melbourne who knows what he's doing with carbon. Scary stuff:

https://www.youtube.com/watch?v=ET1jRVynOBA

[XXtwindad]

Saw a 2018 Campagnolo Bora hub for sale on Gumtree, and msg'd the seller out of curiosity.

Clincher wheel that deformed on a descent. This flys against what I've read about Campy wheels being somewhat better built and more resilient to this stuff. Has me seriously re-thinking my own Bora Clinchers as a performance set - maybe better as a "bling" set on a custom bike for flattish latte rides.

Anyway, found this video of a guy here in Melbourne who knows what he's doing with carbon. Scary stuff:

https://www.youtube.com/watch?v=ET1jRVynOBA

The two takeaway quotes :

"Im not a fan of carbon clinchers. They're poorly designed."

"In a nutshell, if you're going to buy carbon rims, don't buy clinchers."

Pretty much echoes what other Forum members have been saying. I don't need any more convincing...

[Spdntrxi]

The two takeaway quotes :

"Im not a fan of carbon clinchers. They're poorly designed."

"In a nutshell, if you're going to buy carbon rims, don't buy clinchers."

Pretty much echoes what other Forum members have been saying. I don't need any more convincing...

you forgot... learn how to use your brakes....

I've never feared Carbon Clinchers... but I'm on disc now so it's a non-issue from here on out.

[XXtwindad]

you forgot... learn how to use your brakes....

I've never feared Carbon Clinchers... but I'm on disc now so it's a non-issue from here on out.

Well, I've always stopped myself fairly effectively. The video is edifying. The heat tolerance of carbon clinchers is a big issue.

[zap]

Has me seriously re-thinking my own Bora Clinchers as a performance set - maybe better as a "bling" set on a custom bike for flattish latte rides.


Bora's are "super"performance wheels. Clincher version may not be the best when one has multiple high speed switchbacks to negotiate but for everything else.....Bora clinchers are awesomely fast.

[benb]

I rode App Gap quite a few years ago, but I don't remember any issues with either the road or my brakes.


App Gap you might never notice it unless you stopped.

But I've rode a motorcycle over it many times in addition to bikes. I'm originally from VT so when I was up there in the summer before I was married I'd very frequently ride down there on my motorcycle if I'd taken the motorcycle up for the weekend. If I had driven the car, I'd very frequently bike there.

There's something about the mountains near that road that cause an extremely fine dust/powder to wash onto the road. I had a scary moment riding the motorcycle and stopped and you can rub your finger on the road and it will come away covered in dust.

Not noticeable on a bicycle normally.. but if you were in a race going 10/10 down the mountain and started to get near the limit it would make the situation a lot more dangerous cause the dust affects the way the tires behave near the edge of traction.

I don't recall any brake issues.

[redir]

I'm sure pretty much everything has been said already but I didn't read it all :D

But I am also 6'3" 200 pounds and ride almost exclusively carbon tubulars now. It's great! I got a set of Zipp 303's right here on the forum for $250 bucks. I have always used Swiss Stop yellow pads and they work like charm wet or dry. There are even better compounds now like thier Black ones I believe. So welcome to the wonderful world of cheap used carbon rim brake wheels. Nothing like riding what was the top of the line offerings ten years ago for 10% of the price.

I'm all for disk brakes but not for the reasons most would think ;)