Carbon clinchers unsafe?

actusreus

Hello,

I'm thinking of upgrading the stock Mavic wheels that came with my Pinarello Gan, and getting a set of carbon clinchers. Did some research, watched some Youtube videos, and I'm now sort of discouraged by hearing about the braking issue with carbon rims, which can apparently get hot enough for the resin to melt and cause a warp leading to a tire blowout while going downhill. Is this a real issue or something that has been addressed by the manufacturers? I live in California and the organizers of the Gran Fondo race in Northern Cali, with a lot of descents, actually warn participants not to use carbon clinchers due to past incidents with tire blowouts and crashes so it seems it's still a serious and ongoing problem. What are your opinions?

mrb123

viewtopic.php?f=40013&t=13068627

fat daddy

I have blown out a front on aluminium rims .... I put it down to crap braking personally, carbon just requires less crap braking

keith57

Carbon tubs are lighter and are fine engineering wise. Carbon clinchers, according to the Australian engineer on you tube, who works as a consultant to wheel manufacturers, thinks carbon clinchers are just plain wrong.

joe2008

fat daddy wrote:

I have blown out a front on aluminium rims .... I put it down to crap braking personally, carbon just requires less crap braking

That's not crap braking, that's running your aluminium rims until the braking surfaces are too thin.

Carbon clinchers now have improved braking surfaces from the earlier ones, but personally I'd only run with carbon tubulars in a hilly area.

sloppyschleckonds

Crashing isn't the worst thing in the world, unless you die. Then it is.

Anonymous

Carbon clinchers from 5 years ago Yes

Modern better developed clinchers No

Manufacturers have made big leaps in the quality of carbon clinchers. Stick with a recognised brand and not cheap chinese crap.

The scare stories of wheels delaminating and blowing tyres off while zipping down Alp D'huez at 80mph does not apply to someone wanting to just ride their local club run. You would be hard pushed to put newer carbon clinchers under enough strain to be a danger. Tech moves on you know?

taon24

My understanding is that blow outs occur when rims get too hot. Either the rim tape melts and the tube goes through the hole and explodes or the tube gets too hot, melts and explodes or the rim becomes damaged and the sidewall breaks and the tube explodes through the defect.
Clinchers have risks from sidewall breaks, but tubulars can still have the glue holding them in place melt and roll off the rim or the tube inside can melt, so aren't perfect

I understand that aluminium transmits heat better than carbon so the heat is less concentrated and has a larger surface to radiate from. Aluminium does not contain epoxy that can melt at heat achieved by rim braking.
Modern clinchers are better at dealing with heat and less likely to use epoxy that can melt, but it will depend upon the brand.

Aluminium is more forgiving and the safer bet for anyone, but i suspect some smaller lightweight people will get away with carbon clinchers. The assessment will need to be:
1)How long you are descending for (further means more heating).
2) How much energy you need to scrub off (mostly your weight).
3) How continuously you need to brake. (Dragging the brakes all the way down means the brakes never cool.)

ugo.santalucia

taon24 wrote:

My understanding is that blow outs occur when rims get too hot. Either the rim tape melts and the tube goes through the hole and explodes or the tube gets too hot, melts and explodes or the rim becomes damaged and the sidewall breaks and the tube explodes through the defect.
Clinchers have risks from sidewall breaks, but tubulars can still have the glue holding them in place melt and roll off the rim or the tube inside can melt, so aren't perfect

I understand that aluminium transmits heat better than carbon so the heat is less concentrated and has a larger surface to radiate from. Aluminium does not contain epoxy that can melt at heat achieved by rim braking.
Modern clinchers are better at dealing with heat and less likely to use epoxy that can melt, but it will depend upon the brand.

Aluminium is more forgiving and the safer bet for anyone, but i suspect some smaller lightweight people will get away with carbon clinchers. The assessment will need to be:
1)How long you are descending for (further means more heating).
2) How much energy you need to scrub off (mostly your weight).
3) How continuously you need to brake. (Dragging the brakes all the way down means the brakes never cool.)

That's correct... just replace all the MELT with SOFTEN / WEAKEN. Neither rubber nor epoxy resins do melt... they are thermo-sets, melting is a property of (some) thrmo-plastics

Anonymous

taon24 wrote:

The assessment will need to be:
1)How long you are descending for (further means more heating).
2) How much energy you need to scrub off (mostly your weight).
3) How continuously you need to brake. (Dragging the brakes all the way down means the brakes never cool.)

This would apply for very long steep descents of which you may come across in the alps or pyrenees but very unlikely to find in the UK. 99.9% or your riding is not likely to even come close to being so steep or fast that you are going to create a lot of heat build up. And if you were it would make sense to use a different wheelset for just that time. Rolling British countryside is not a challenge for modern carbon clinchers. A set of Fulcrum Carbon Quattro's would offer a good mix of aero and weight in a clincher while being reasonably affordable.

ugo.santalucia

Maglia Rosa wrote:

This would apply for very long steep descents of which you may come across in the alps or pyrenees but very unlikely to find in the UK.

That's a bit of a myth, there are technical steep and long enough descents in the UK. In fact the scariest descents I have ever done are all in the UK. Heat doesn't build up over minutes, the timescale is seconds... drag your brakes for 10 seconds trying to scrub significant speed and you might be in that ball game.

On a tail wind day I have overcooked the brake pads/rotor coming down Buttertubs pass, which is by no means the steepest you will find in the land.. I simply picked up to much speed

Anonymous

ugo.santalucia wrote:

Maglia Rosa wrote:

This would apply for very long steep descents of which you may come across in the alps or pyrenees but very unlikely to find in the UK.

That's a bit of a myth, there are technical steep and long enough descents in the UK. In fact the scariest descents I have ever done are all in the UK. Heat doesn't build up over minutes, the timescale is seconds... drag your brakes for 10 seconds trying to scrub significant speed and you might be in that ball game.

On a tail wind day I have overcooked the brake pads/rotor coming down Buttertubs pass, which is by no means the steepest you will find in the land.. I simply picked up to much speed

I didn't say they don't exist (read what I wrote ) I said they are few and far between. The 'average' ride is not that mountainous and it it were then pick a suitable wheel in the first place. And again, newer clinchers are better quality than the scare story wheels of a few years ago

ugo.santalucia

Maglia Rosa wrote:

I didn't say they don't exist (read what I wrote ) I said they are few and far between. The 'average' ride is not that mountainous and it it were then pick a suitable wheel in the first place. And again, newer clinchers are better quality than the scare story wheels of a few years ago

Depends what your average ride is.. I assume the club Honister 92 go up and down Honister/Newlands pass week in week out and cyclists in the dales go down Garsdale Head often... I don't think there is an "average ride" to be honest

Incidentally the most popular sportives are in fairly mountainous regions too

Anonymous

ugo.santalucia wrote:

Maglia Rosa wrote:

I didn't say they don't exist (read what I wrote ) I said they are few and far between. The 'average' ride is not that mountainous and it it were then pick a suitable wheel in the first place. And again, newer clinchers are better quality than the scare story wheels of a few years ago

Depends what your average ride is.. I assume the club Honister 92 go up and down Honister/Newlands pass week in week out and cyclists in the dales go down Garsdale Head often... I don't think there is an "average ride" to be honest

Incidentally the most popular sportives are in fairly mountainous regions too

The average ride for the average person. Do you do hilly sportives every single ride? People need to get away from this idea there is or ever will be a universal does everything wheelset frameset or tyre etc. You pick the components to suit the course or vice versa. Sure there are hilly routes out there and some very steep descents but they are not an everyday challenge unless you live in such areas. I doubt a rider in Norfolk is worried about fast descents. If a route has a tricky descent then don't use carbon clinchers. For my average ride I could cover 100km and do abou 700 to 1000 metres climbing and still not come across a dodgy descent for carbon clincher wheels. This includes rides in up to around the peak district

kayakerchris

700m of climbing for a 100km ride is pretty flat. I suspect many club riders in the Peaks, Wales, Scotland will be doing 1500-2000m of climb for a 100km ride.

Anonymous

kayakerchris wrote:

700m of climbing for a 100km ride is pretty flat. I suspect many club riders in the Peaks, Wales, Scotland will be doing 1500-2000m of climb for a 100km ride.

Does this constitute the average ride by the average UK rider? Pulling an extreme example is not the average. Again. The AVERAGE ride in the UK is not perticularly mountainous. I wouldn't use the same wheels on a hilly ride as I would on a flat TT for example. But I would quite happily ride around the my average route all year round on carbon. If I did this around 200 days of the year or so I think they would be perfectly sensible options

ugo.santalucia

Maglia Rosa wrote:

Do you do hilly sportives every single ride?

I try to as much as possible...

ugo.santalucia

kayakerchris wrote:

I suspect many club riders in the Peaks, Wales, Scotland will be doing 1500-2000m of climb for a 100km ride.

That sounds about average in the Peaks, unless one tries to avoid the climbs...

I think Maglia Rosa should live up to his name...

Anonymous

ugo.santalucia wrote:

Maglia Rosa wrote:

Do you do hilly sportives every single ride?

I try to as much as possible...

Really? Every single ride you do is a 100+km sportive? How do you find the time between chatting sh1t?

I like to mix up my rides. I ride flat. I ride hills. I ride TTs. I do recovery rides. I do club rides. If your life consists of day after day of HC climbing them well done you. I'll get onto the Queen to rush through your medal you hero

Anonymous

Back to the OP. Nothing wrong with carbon clinchers. They are better than they used to be. Look at the riding you do and decide yourself. If you intend riding down a sheer cliff then maybe they aint for you but other than that they will do you justice

ugo.santalucia

Maglia Rosa wrote:

Really? Every single ride you do is a 100+km sportive? How do you find the time between chatting sh1t?

Charming...

I try to, as much as possible, as I said... but I am only at no. 8 on this forum, there are folks who try a lot harder and do twice as many as I do...

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taon24

OP lives in California, where there are mountains.

It is persistent heating the rims which causes problems, for example long periods of dragging the breaks and having already heated the rims will make dragging the brakes more risky.
Peak heat at the rim (i.e. short periods of harder braking with periods of the brake being off as opposed to longer periods of moderate braking) can actually be useful as it improves the heat removal of the rims, while the problems will be when the rims get hot for a while.

stueys

taon24 wrote:

OP lives in California, where there are mountains.

Glad someone pointed that out!

My view is that the technology has moved on and carbon clinchers are far safer than they were. If you understand the inherent limitations, and ride within them, then you'll be fine. I ride a set in the chilterns (UK) which has lots of steep descents but no long mountain descents. I wouldn't be worried about riding carbon clinchers on the roads I've ridden in California (Bay Area and San Diego).

Having said that I switch to my alloy rims for when I hit the European mountains. Two reasons, one is weather - the braking performance on carbon wheels is still pretty poor and combining that with a steep descent isn't high on my fun scale; two is the heat issue, I think a normal descent would be perfectly fine but I've had two descents in the Alps where I haven't been able to ride at the speed I normally would and have been braking heavily (heavy traffic). I would have been twitchy on carbon clinchers in those circumstances, so for peace of mind I switch.

Summary is that I think the newer wheels are safe as long as you ride within the narrower margins that you have.

sloppyschleckonds

Maglia Rosa wrote:

Really? Every single ride you do is a 100+km sportive? How do you find the time between chatting sh1t?