Carbon Wheel Vlog (not mine)

[rePhil]

Interesting thoughts about carbon. Just when i was ready for some Bora clinchers

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

[FlashUNC]

1) They have bikes down at the Prison Colony in the Southern Hemisphere now?

2) Bora Tubulars. The only way to travel.

[Davist]

Liked the part about how to "kudo" everyone on a group ride at once on strava

then 12+ minutes I got bored in 30 seconds, sorry..

[sitzmark]

Surprised this is dated 2016. Not exactly news is it? 2-3 years ago maybe, but not today. Braking technique important when climbing/descending with CCs - helps but doesn't guarantee.

[thwart]

Nice explanation of the current movement to disc brakes in road bikes... at least for those riding carbon clinchers, anyway.

Or as Old Spud would describe them, Nancys. ;) :D

[mike mcdermid]

the Aussies always 10 years behind the curve

[Veloo]

Never heard the term "singles" before.

[Burnette]

Well, not everybody is "up on it" and to me there was one data point I would like to see expounded upon. Many of us won't do tubulars and want clinchers. The video gave out some info about how clinchers have evolved.

As stated in the video and seemingly known to some here, tubulars dissipate heat better due to the extra material at the braking surface. Some carbon clinchers have just a thin wall at that same braking surface. Because it is a stand alone thin surface, it is more easily overwhelmed with prolonged hard braking.

The video says that manufacturers of carbon clinchers get around this by putting the braking surface lower over the rim, right at the "T" junction where there is more material. It now then has the same advantage as a tubular in that it has more material to soak up heat.

What I want to see now from the people making this video is a list a carbon clincher rims that incorporate this feature. That would be usable information.

[sitzmark]

Not so much that tubulars are better at dissipating heat (to the atmosphere) but that they are better "distributors" of heat due to having more material at the braking interface to transfer heat away from the surface. Carbon is a very good insulator/conductor. In comparison to aluminum heat will remain in carbon and not dissipate to the environment as quickly.

The advantage tubulars have is structural. When trapped heat builds to a point where the "secret sauce" binding the carbon laminate together is in danger of softening, tubulars don't have a growing lateral force pushing against open ended uprights. Think about what the cross section of a clincher rim looks like. Tubular tires still heat up as the carbon in contact with them absorbs and transfers heat, but the force exerted by the expanding tire is pushed down through the bridge of the rim and into the sidewalls. That structure is a closed "triangle".

In addition to whatever secret sauce Zipp claims to have, they also spent a lot of engineering time with carbon bridge design and placement in Firecrest clinchers to strengthen the interface. That and making the rims (clincher sidewalls) thicker/wider ... so not only have carbon clinchers lead a revolution into disc brakes, they also played into the wider-is-better revolution. Mavic incorporated an aluminum rim bed into their "carbon" clinchers to dissipate heat and resist deformation. In that way they didn't have to go wide ... at least not for structural reasons ...marketing pressure is another story. Zipp (and others) added more carbon and made them wider to shore things up.

Zipp heat failures are rare - I'm aware of none and Zipp claims none, but it's a big world out there. Enve has a good reputation, but I do have friends who have slightly blistered their Enve brake tracks descending. Enve warranty replaced them all with no questions asked. I'm still hesitant riding my Firecrests when I anticipate any significant amount of descending. Instead I'll opt for the Mavic CC 40C with the alu insert, hybrid Zipps, or an alu rim.

As for "moving" brake tracks down, I don't know what rims feature that to any significant degree. There's only so far you can shift things before you have brake caliper incompatibilities.

[regularguy412]

snipped==

As for "moving" brake tracks down, I don't know what rims feature that to any significant degree. There's only so far you can shift things before you have brake caliper incompatibilities.

The Mercury M5 clinchers that I just started riding this year came with an approximate 2.5 - 3 mm width sticker right up next to the outer circumference of the brake track. That is the width of the 'drop' that this rim manufacturer suggests one move the pads down toward the center of the wheel. I suspect that is so that the heat and pressure from braking is centered a bit closer down to the rim bed.

Mike in AR :beer:

[sitzmark]

The Mercury M5 clinchers that I just started riding this year came with an approximate 2.5 - 3 mm width sticker right up next to the outer circumference of the brake track. That is the width of the 'drop' that this rim manufacturer suggests one move the pads down toward the center of the wheel. I suspect that is so that the heat and pressure from braking is centered a bit closer down to the rim bed.

Mike in AR :beer:

Good to know. Thanks Mike. :beer:

[Burnette]

Not so much that tubulars are better at dissipating heat (to the atmosphere) but that they are better "distributors" of heat due to having more material at the braking interface to transfer heat away from the surface. Carbon is a very good insulator/conductor. In comparison to aluminum heat will remain in carbon and not dissipate to the environment as quickly.

The advantage tubulars have is structural. When trapped heat builds to a point where the "secret sauce" binding the carbon laminate together is in danger of softening, tubulars don't have a growing lateral force pushing against open ended uprights. Think about what the cross section of a clincher rim looks like. Tubular tires still heat up as the carbon in contact with them absorbs and transfers heat, but the force exerted by the expanding tire is pushed down through the bridge of the rim and into the sidewalls. That structure is a closed "triangle".

In addition to whatever secret sauce Zipp claims to have, they also spent a lot of engineering time with carbon bridge design and placement in Firecrest clinchers to strengthen the interface. That and making the rims (clincher sidewalls) thicker/wider ... so not only have carbon clinchers lead a revolution into disc brakes, they also played into the wider-is-better revolution. Mavic incorporated an aluminum rim bed into their "carbon" clinchers to dissipate heat and resist deformation. In that way they didn't have to go wide ... at least not for structural reasons ...marketing pressure is another story. Zipp (and others) added more carbon and made them wider to shore things up.

Zipp heat failures are rare - I'm aware of none and Zipp claims none, but it's a big world out there. Enve has a good reputation, but I do have friends who have slightly blistered their Enve brake tracks descending. Enve warranty replaced them all with no questions asked. I'm still hesitant riding my Firecrests when I anticipate any significant amount of descending. Instead I'll opt for the Mavic CC 40C with the alu insert, hybrid Zipps, or an alu rim.

As for "moving" brake tracks down, I don't know what rims feature that to any significant degree. There's only so far you can shift things before you have brake caliper incompatibilities.

That's what I'm talking about! Thanks for your post.

[Burnette]

The Mercury M5 clinchers that I just started riding this year came with an approximate 2.5 - 3 mm width sticker right up next to the outer circumference of the brake track. That is the width of the 'drop' that this rim manufacturer suggests one move the pads down toward the center of the wheel. I suspect that is so that the heat and pressure from braking is centered a bit closer down to the rim bed.

Mike in AR :beer:

Thanks for sharing Mike. I wonder how many other rim makers are doing this?

Carbon clinchers on my next bike would be a vanity choice first to be honest and hopefully a decent wheel second. But knowing they could handle the hills around here and the heat they would generate would satisfy my obsessive compulsive personality disorder side enough that I could rationalize the purchase. If at the very least, they performed well, why not?

If they don't, looks be damned, I wouldn't go that route. I've got some mean hills around here. My area is mostly rollers but I do have some 42 mph to 25 mph descents that are common on routes I ride.

[regularguy412]

Just for the sake of how mine look, I thot I'd post a pic. The sticker and the writing on it are VERY small, so the writing is a bit out of focus.

Mike in AR:beer: