Carbon tubulars better than clinchers for dealing with brake track heat on descents?

[cyan]

Heard on a ride today that carbon tubulars are less susceptible to brake track heat problems than clinchers because the the track section are thicker and structurally stronger. Not sure if there is any truth/science about that.

Could any tubular owners share their experiences?

[ultraman6970]

I dont use carbon tubulars, but aluminum just because of costs. That being said, it makes sense what they told you, you go figure if its true or if somebody did a test to confirm it. With aluminum you dont have to worry pretty much of anything, clinchers or tubulars.

[FriarQuade]

If we are talking carbon wheels, tubulars are absolutely more reliable and safer in heavy braking conditions. But it doesn't have anything to do with the brake track.

In a clincher the rim is part of the pressurized structure. So as you brake and the heat increases tire pressure the rim takes part of those forces. As the resins in the carbon laminate reach their plastic state the pressure from the tire pushes out on the brake track, creating a failure.

In a tubular the entire pressure vessel is contained with in the tire, meaning it will hold full pressure even if it's not on a rim. So when a tubular heats up under heavy breaking the rim doesn't see any extra forces and as a result is significantly more reliable.

[StephenCL]

Well said above...I can tell you that a good buddy of mine, who is a very good descender and likes to go very fast, has gone through 4, yes 4 sets of Enve Clincher Carbons... they finally just told him he needs to move to tubulars!

They have all delammed at the brake track, and he only brakes before the corner and does not ride his brakes at all...

Stephen

[false_Aest]

What the holy man said.
I would never, ever ride on rim brake CF clinchers in the mountains. I've seen too many folks ruin their rims descending around here -- these are good, high quality, respectable MFGs not just open mold stuff.


In my own experience I have yet to have an issue with a tubular CF rim and I've definitely done some stupid shiz with them.

[pianobike]

I've had some early gen clincher rims delaminate in the CA 95deg heat with fast descents- no fun, but they held air! Tubulars are the safest choice.
Check out Tim Smith's GS Astuto (in Tokyo), he's studied rim shapes/resins/weave and has a great handle on rims that resist delamination.

[FlashUNC]

If you want carbon wheels, tubular is the only way to go imo.

[oldpotatoe]

Originally Posted by flashunc

if you want new wheels, tubular is the only way to go imo.

fify...

[Blown Reek]

Originally Posted by FriarQuade

If we are talking carbon wheels, tubulars are absolutely more reliable and safer in heavy braking conditions. But it doesn't have anything to do with the brake track.

In a clincher the rim is part of the pressurized structure. So as you brake and the heat increases tire pressure the rim takes part of those forces. As the resins in the carbon laminate reach their plastic state the pressure from the tire pushes out on the brake track, creating a failure.

This has everything to do with the brake track.

[dem]

Originally Posted by Blown Reek

This has everything to do with the brake track.

Certainly more mass, and higher temperature resins, and a better insulating brake track will help. But all resins will fail at high temperature, and the description above is accurate regarding the forces that make carbon clincher failure a problem.

I only ride carbon clinchers with disc brakes (500K ascent/year)

[Wayne77]

Originally Posted by StephenCL

Well said above...I can tell you that a good buddy of mine, who is a very good descender and likes to go very fast, has gone through 4, yes 4 sets of Enve Clincher Carbons... they finally just told him he needs to move to tubulars!

They have all delammed at the brake track, and he only brakes before the corner and does not ride his brakes at all...

Stephen

I know exactly who you’re talking about. I’ve been on carbon tubulars for 3 years now (thanks to you!) and with all the long steep mtn descents around here I’m not going back to carbon clinchers. I got to the bottom of the Powder mtn descent, which is the steepest climb in Utah by a wide margin and my tubular brake tracks were sizzling hot...I use the correct methods for high speed descending too. I’m not a paranoid person by nature, and in fact I have a fairly high risk tolerance with downhill riding but I really don’t think I’d ever want do that descent on cf clinchers. The worst case scenario / brake track failure possibility makes me shudder to think about.

The other side of the sword is if there IS a clincher fail of some sort also causing rapid loss of tire pressure on a fast descending corner, the rim is going to be right on the pavement and things will go south very quickly. There are extreme occasions even with tubulars of course, but with a tubular the tire is going to stay put to maintain traction for a controlled stop.

Another related question comes to mind...is the cf clincher overheating brake track risk being discussed here better or worse with a tubeless setup? Or maybe it makes no difference. Maybe Im wrong but doesn’t a tubeless tire exert more pressure on the rim? I keep hearing people tell me that I can inflate a gravel tire on a tubeless rim to higher pressures with a tube.

[Wayne77]

Originally Posted by dem

Certainly more mass, and higher temperature resins, and a better insulating brake track will help. But all resins will fail at high temperature, and the description above is accurate regarding the forces that make carbon clincher failure a problem.

I only ride carbon clinchers with disc brakes (500K ascent/year)

Another key point. I suppose I should clarify by including “rim brake” in my statements about not ever wanting to do long/fast descending on cf clinchers

[martl]

Originally Posted by cyan

Heard on a ride today that carbon tubulars are less susceptible to brake track heat problems than clinchers because the the track section are thicker and structurally stronger. Not sure if there is any truth/science about that.

Could any tubular owners share their experiences?

Carbon fibre is incredibly strong in direction of the fiber (tensional stress) but sucks at dealing with bendings, as this stresses mostly the resin instead of the fiber.
A clincher does suffer bending force on the brake sides from tire pressure and from the brakes.
So, making a good a CFK clincher is either a challenge (if you're an optimist) or a bad idea (if you're a pessimist). When i was still actively scanning the market which was like 5 years ago, there were very few manufacturers i would have trusted to get it right.

About brake heating, CFK in general does a bad job of getting the heat away as opposed to alloy, and tubulars deal better with heat than clinchers because there can be no direct contact between the tube and the rim. On the other hand, the tubular glue may react to the heat as well; this is a konwn phenomenon even when using alloy tubulars.

When descending alone, i never had any issues with either CFK tubulars or alloy clinchers. I have been in a field of 500 riders being lead downhill by a leading car at an average speed of 35km/h which forced everyone to descend with brakes applied from top to botton and the soundtrack was comparable to a large group of lemmings in a minefield - tires explodedliterally all the time. Can't tell if there was a majority of one rim type affected

[quickfeet]

Just buy a fancy new disc brake wonder bike and you’ll never need to worry about rim brake tracks again.

But for real, some rims are better than others when it comes to rim brake tracks on clinchers. Do your research and you’ll be fine.

[pdmtong]

What is the sustained temperature and duration the brake track of a given CF clincher rim would need to heat to in order for it to fail? And how does that translate into rider weight pad pressure descent slope and speed? How is that affected by drag : pulse brake techniques?

Folks living where there are multi mile high speed downhills. - does anyone there use CF clinchers? Isn't enve in Utah? What do they say?

I think if you want a universal rule then it would be carbon for tubulars for a rim brake application.

Yet enve and campagnolo to name a few offer CF clinchers - are these without fine print?