Chinese carbon clincher WARNING!!!

lawrences

Manc33 wrote:

I wanted some until I found you can actually get cheaper lighter aluminium wheelsets.

It makes sense with frames, my carbon frame was only £350 bought in the UK (Chinese frames cost £125 to return to China) and it is 2/3 of the weight of the aluminium frame it replaced. With carbon wheels its a whole other thing. I don't know any logical reason to have carbon clinchers or even the disc versions.

What gets me is they put a strip of aluminium around some carbon clincher rims. :shock: I thought carbon and aluminium (or CF+titanium or CF+steel) shouldn't be touching? What a place to have that, on a sodding braking surface.

It's an aluminium rim with a carbon aero section, very common nowadays.

But you should probably email all those companies who produce these kind of wheels and inform them of your knowledge.

ugo.santalucia

I think the moral is if you want carbon fibre that performs under those conditions, you need to spend serious money. Otherwise, untried and largely untested chinese/taiwanese rims will still give you the aero advantage and the desired PRO look, but not the PRO performance (call it peace of mind, if such thing exists in cycling).

martinperry

ugo.santalucia wrote:

I think the moral is if you want carbon fibre that performs under those conditions, you need to spend serious money. Otherwise, untried and largely untested chinese/taiwanese rims will still give you the aero advantage and the desired PRO look, but not the PRO performance (call it peace of mind, if such thing exists in cycling).

Absolutley spot on

Bar Shaker

ugo.santalucia wrote:

I think the moral is if you want carbon fibre that performs under those conditions, you need to spend serious money.

If no one told the OP, I have a small amount of sympathy but you can't expect £300 wheels to be as good as £2300 wheels and you can't expect any carbon wheel to be good at stopping a 95kg rider on very steep descents. The wheel type just isnt made for that use.

There are plenty of people that have wrecked mid priced carbon rims (Fast Forward etc) in Majorca and a few that have wrecked high end wheels (Zipps, Enve etc) there too. Within a second or two of hitting the brakes at high speed, the temps will be close to the limit of the resin. If you keep the brakes on, they will quickly pass this limit. The correct technique is to use high braking pressure for a couple of seconds then let the wheels cool.

I'm 20kg lighter than the OP and I wouldn't dream of taking my Chinese carbons on anything much higher than the hills of Essex. Besides, they are built for high speeds on the flat, not for climbing.

At £300 a pair, you'd just buy another set Carbonzones, or even just another single wheel. The only company giving a full no quibble guarantee on this sort of failure is Mavic with the 40C. They cost eight times the price of the OP's Carbonzones!! So as Ugo says, if you want bullet proof, you need to spend serious money.

None of this will stop me enjoying my Far Sports, but I still have my Ksyriums for the mountains.

graeme_s-2

I used to see this Keith Bontranger quote on here a lot, but haven't seen it in a while and it's worth keeping in mind:

"Strong. Light. Cheap. Pick Two."

Grill

Graeme_S wrote:

I used to see this Keith Bontranger quote on here a lot, but haven't seen it in a while and it's worth keeping in mind:

"Strong. Light. Cheap. Pick Two."

I was just thinking this...

rolf_f

Graeme_S wrote:

I used to see this Keith Bontranger quote on here a lot, but haven't seen it in a while and it's worth keeping in mind:

"Strong. Light. Cheap. Pick Two."

That was as original when Bontrager said it as the supposed 'Triggers broom' joke was original when it appeared on Only Fools and Horses.

And it isn't true these days either!

pinno

Graeme_S wrote:

I used to see this Keith Bontranger quote on here a lot, but haven't seen it in a while and it's worth keeping in mind:

"Strong. Light. Cheap. Pick Two."

This is also known as the 'Triple constraint'.

Back on topic. I have Shimano Carbon 1380's (predecessor of the CL40's), fantastic wheels. Never had a problem with them but then A I am less than 65kg's and B I am Harem Scarem on the downhills so breaking is mainly feathering.
I remember being passed up Shiehallion in the Etape by oooh too many for comfort (due to a chest infection) and then passing oooh, too many to remember going down it - wooses, the lot of them. Funny how the nervous one's are on the brakes all the time. (No reference to the OP). The Mavics are bullet proof and a great choice for the heavier rider.

diy

On the subject of braking technique, I would say a lot of very good riders understand very little about braking/cycle dynamics or even lines round bends. So many riders will take a racing line on a left hander or brake when they are making other demands on the tyre (like cornering). Acceleration, braking and corning all place demands on the tyre. The same myths about dragging the rear brake exist in the motorcycle world.

We are not normally on closed road races, so racing lines should really be seen for what they are - high risk.

One thought on the OPs post is on the brake pads used. This can make a massive difference to the ability of brakes to work with out excessive load on the rim.

ugo.santalucia

diy wrote:

One thought on the OPs post is on the brake pads used. This can make a massive difference to the ability of brakes to work with out excessive load on the rim.

Is this the case? My simple physics notions suggest braking is 100% trasforming kinetic energy into heat, so it's irrelevant which pads you use, unless the pads have a specific ability to suck and dissipate heat. Being by and large insulating material, I would assume this is not the case.

You seem to suggest kinetic energy can be transformed into something else, if not heat... what then? :roll:

arthur_scrimshaw

ugo.santalucia wrote:

diy wrote:

One thought on the OPs post is on the brake pads used. This can make a massive difference to the ability of brakes to work with out excessive load on the rim.

Is this the case? My simple physics notions suggest braking is 100% trasforming kinetic energy into heat, so it's irrelevant which pads you use, unless the pads have a specific ability to suck and dissipate heat. Being by and large insulating material, I would assume this is not the case.

You seem to suggest kinetic energy can be transformed into something else, if not heat... what then? :roll:

Noise!

ugo.santalucia

Arthur Scrimshaw wrote:

ugo.santalucia wrote:

diy wrote:

One thought on the OPs post is on the brake pads used. This can make a massive difference to the ability of brakes to work with out excessive load on the rim.

Is this the case? My simple physics notions suggest braking is 100% trasforming kinetic energy into heat, so it's irrelevant which pads you use, unless the pads have a specific ability to suck and dissipate heat. Being by and large insulating material, I would assume this is not the case.

You seem to suggest kinetic energy can be transformed into something else, if not heat... what then? :roll:

Noise!

Interesting, but a 15 Watt speaker is way louder than a set of brakes, which would suggest there isn't much there...

mercia_man

It's not comparing like with like when people say how confident they are descending on carbon laminate clincher wheels with alloy braking surfaces like Shimano 1380 or C50. The OP's problems were with full carbon clinchers with a carbon braking surface claimed by the manufacturer to be resistant to high temperatures. These cheap wheels obviously did not match up to those claims and it was useful to hear of Martin's experience with them.

When I was buying a new bike earlier this year, several of the bikes I was considering came with full carbon clinchers as standard and I asked forum users with experience of these whether they would be safe to use in high mountains such as the Alps. I got the usual stuff about poor braking technique from people who think they can descend like Nibali but also several useful accounts of carbon clincher failures in events such as the Etape where people are riding in large groups in the heat down long mountain descents.

I thought about this yesterday when I did a 35-mile ride in the heat over the Stiperstones and Long Mynd hills in Shropshire. Going down 20 per cent descents on gravelly single track roads when you are likely to meet a combine harvester or tractor towing bales round the next blind bend (I had to brake to a standstill on three occasions) means you have to keep your brakes on for lengthy periods. I reckon my rims probably got hotter than when I descend in the Alps and only have to brake on the approaches to hairpins. I was glad I was on alloy rims (Archetypes) with superior braking power and feel and no likelihood of the braking surface distorting from poor heat dissipation.

I have only had one experience of riding carbon rims - Enve - which were OK but definitely inferior in braking power and feel to alloy rims.

The more I read the more I feel that full carbon clinchers with rim brakes are only suitable for flatland riding for people who like pro-style appearance and are prepared to put up with compromised braking performance. They are much more suited to a bike with disc brakes.

rolf_f

Another point about descending is that no matter how Cancellara you might be on your own, in a group you will be on the brakes a lot more. And you won't necessarily be wanting to be jabbing the brakes on and off in such circumstances. Fine if you know you'll always be descending on your own but what if it happens that one day you don't?

arthur_scrimshaw

ugo.santalucia wrote:

Arthur Scrimshaw wrote:

ugo.santalucia wrote:

diy wrote:

One thought on the OPs post is on the brake pads used. This can make a massive difference to the ability of brakes to work with out excessive load on the rim.

Is this the case? My simple physics notions suggest braking is 100% trasforming kinetic energy into heat, so it's irrelevant which pads you use, unless the pads have a specific ability to suck and dissipate heat. Being by and large insulating material, I would assume this is not the case.

You seem to suggest kinetic energy can be transformed into something else, if not heat... what then? :roll:

Noise!

Interesting, but a 15 Watt speaker is way louder than a set of brakes, which would suggest there isn't much there...

No I wasn't suggesting it was significant but it's probably the next one after heat but ahead of X-Rays and the like!

ugo.santalucia

Arthur Scrimshaw wrote:

No I wasn't suggesting it was significant but it's probably the next one after heat but ahead of X-Rays and the like!

Yeah, according to Boltzmann equation, it's very unlikely you can generate an excited electron thermally, let alone one capable of decaying with an X-ray emission.... :shock:

diy

ugo - Google Coefficient of friction. Different materials achieve different results. It is a factor of the materials used and the forces squeezing the two surfaces together. To achieve a certain amount of braking force you have two options for a given scenario where the tyres mass, angle, road surface etc are all fixed. Increase the force between the two surfaces or increase the coefficient of friction.

in summary low coefficient of friction = more force required (e.g. try some brake pads made of wood or teflon coated), high coefficient = less force. Hence since its not clear if the rim was partly crushed under heavy braking a more effective pad (with a higher coefficient of friction) might have achieved more efficient braking with less force on the rim.

ugo.santalucia

diy wrote:

ugo - Google Coefficient of friction. Different materials achieve different results. It is a factor of the materials used and the forces squeezing the two surfaces together. To achieve a certain amount of braking force you have two options for a given scenario where the tyres mass, angle, road surface etc are all fixed. Increase the force between the two surfaces or increase the coefficient of friction.

in summary low coefficient of friction = more force required (e.g. try some brake pads made of wood or teflon coated), high coefficient = less force. Hence since its not clear if the rim was partly crushed under heavy braking a more effective pad (with a higher coefficient of friction) might have achieved more efficient braking with less force on the rim.

Sure but the heating is the same... you are converting kinetic energy into heat either way and the first law of thermodynamics tells you that the heat generated to stop that mass at that speed is constant regardless.

martinperry

For information, the pads were the original ones supplied by Carbonzone
Had bought a set of Swissstops expecting the chinese ones to be crap, but was pleasantly surprised finding them nicely modulated and pretty powerful (unless wet!)

Carbonzone got straight back asking for more information, so I will keep you posted!!

If they offer me another set, anyone living in Norfolk or holland want to make me an offer?? :roll:

rolf_f

martinperry wrote:

For information, the pads were the original ones supplied by Carbonzone
Had bought a set of Swissstops expecting the chinese ones to be crap, but was pleasantly surprised finding them nicely modulated and pretty powerful (unless wet!)

Carbonzone got straight back asking for more information, so I will keep you posted!!

If they offer me another set, anyone living in Norfolk or holland want to make me an offer?? :roll:

They'll probably offer you a replacement on the basis that you return the wrecked rim and pay the postage (which will cost most of the value of the wheel).........

diy

ugo.santalucia wrote:

Sure but the heating is the same... you are converting kinetic energy into heat either way and the first law of thermodynamics tells you that the heat generated to stop that mass at that speed is constant regardless.

nobody said anything to the contrary.. You questioned my statement that the pads can make a difference to the amount of force applied to the brakes to stop them. I've just shown you why and now you seem to agree with me.

ugo.santalucia

diy wrote:

nobody said anything to the contrary.. You questioned my statement that the pads can make a difference to the amount of force applied to the brakes to stop them. I've just shown you why and now you seem to agree with me.

No, I questioned that it makes no difference to the problem discussed on this thread, which is overheating and not braking efficiency.... I think we misunderstood each other... :roll:

BrandonA

martinperry wrote:

Lawrences - I think you have worked out where I am coming from - I am a tight wad as well!

I think this sums it up.

Cycling can be an expensive hobby and not everyone is able or willing to buy the best quality products that are available.

I think though if you buy knock-offs or cheap junk from places like China you have to expect it not to function identically to the more expensive quality products. This is not just limited to cycling but all walks of life. I truly believe you get what you pay for.

There are numerous accounts of fake frames snapping under strain, so I guess it makes sense the wheels will under perform too.

Having said the above, I can emphasis with you. It must have been scary going down the descent and experiencing a mechanical issue. As you say, luckily you were not going at a great speed and at least you walked away unhurt and can learn from this experience.

goonz

This thread has got me worried.

Im taking my Reynolds Assaults with me to the pyrennees in August for 3-4 days of col climbing and descending. I got some new Reynolds Cryo pads to take with me but now im wondering whether I should be leaving the wheelset at home?

I weigh 65kg if that helps?

martinperry

Obviously the Reynolds are a quantum leap in quality relative to the Carbonzones, however, the Guy in the LBS who fixed me up was quite firm that "NO ONE round here rides carbon"
But at 65Kg you are putting immensely less energy into the brakes than I am
I know I wont be touching all carbon rims again until i go to disc brakes.
Dura Ace C35s ordered!

Bar Shaker

goonz wrote:

This thread has got me worried.

Im taking my Reynolds Assaults with me to the pyrennees in August for 3-4 days of col climbing and descending. I got some new Reynolds Cryo pads to take with me but now im wondering whether I should be leaving the wheelset at home?

I weigh 65kg if that helps?

Take some lightweight alloy climbing wheels and leave your Assaults for the high speed flat(ish) rides.

charlie_potatoes

Bar Shaker wrote:

goonz wrote:

This thread has got me worried.

Im taking my Reynolds Assaults with me to the pyrennees in August for 3-4 days of col climbing and descending. I got some new Reynolds Cryo pads to take with me but now im wondering whether I should be leaving the wheelset at home?

I weigh 65kg if that helps?

Take some lightweight alloy climbing wheels and leave your Assaults for the high speed flat(ish) rides.

+1

And I am 65.3kgs so nearly caught you up 8)

pinno

martinperry wrote:

Obviously...to disc brakes.
Dura Ace C35s ordered!

FWIW, the C35's will do you proud. I am a campag man through and through but my DA wheels are the best I have ever owned. The Eurus's I have are great for all round use but they are not as good as the 1380's.
Flat roads are all very well but they are missing an essential ingredient - hills.

gingejp

Rolf F wrote:

martinperry wrote:

For information, the pads were the original ones supplied by Carbonzone
Had bought a set of Swissstops expecting the chinese ones to be crap, but was pleasantly surprised finding them nicely modulated and pretty powerful (unless wet!)

Carbonzone got straight back asking for more information, so I will keep you posted!!

If they offer me another set, anyone living in Norfolk or holland want to make me an offer?? :roll:

They'll probably offer you a replacement on the basis that you return the wrecked rim and pay the postage (which will cost most of the value of the wheel).........

I had a similar experience with cheap chinese carbon wheels and I think you may find Rolf is right. They offered to replace mine, but only if post was paid in both directions, which was more than buying a new wheel. As, like me, you know you shouldn't have bought them in the first place, you know it won't be worth it.

A company called Farsports seemed to be the best bet just in case you were thinking about getting more carbon wheels in the future.

Pleased you came to no harm anyway OP. Enjoy your new Dura-Ace wheels. I'm back on trusty Aksiums.

Bar Shaker

I am quite surprised that no one has owned up to doing this on their Zipps/Reynolds/Enve/Mavics/FF/Lightweights.

The problem applied to all deep carbon wheels only a few years ago.

If you bought a new set of Carbonzone every year, it would be 6 years before you spent the cost of a set of Mavic 40C wheels. A set of Lightweights would be over 10 years away. Both of those will be old tech by their pay back date, but you will be buying almost the latest designs and the latest material technology, with each new set of cheaper wheels.

It is very likely that the cheaper wheels will be using identical processes, design and technology well before the pay back period.

My Farsports were almost twice the price of Carbonzone but are very well made and have some good claims about their tech. I like that the spoke tension is stated on the wheels and that the brake track is clearly marked by a 'no pad zone' sticker. If I wrecked them, down a big descent that overheated them well beyond their capacity, I'd accept that I had exceeded their limits and buy another set.

By then, they will probably have carbon-ceramic crystal brake tracks, like F1 brake discs.