Index Categories:
Carbon Construction – Braking concerns with carbon
From:
bikerbrian Jan 20, 2006, 3:37 AM
Question:
Carbon Tubular Breaking Surface?
I'm new to the world of carbon wheels and was wondering about the braking surface of these wheels. I know you need to use special pads and that breaking will not be as good but my question is this, is there any problem with the brake surface wearing down? Carbon wheels seem sort of fragile to me and it seems like this could be a problem. I don't have any experience but wanted to get some opinions before paying an ungodly amount for some Zipp 808's. Any help is appreciated, Thanks in advance
Josh:
From a data point of view, the braking of carbon rims is very specific to the manufacturer, so you will generally be best to do what they recommend. Our silica ceramic surface is actually slightly more agressive than aluminum when dry and about 96% as effective when wet when using the specific Zipp pad. Many rims like those from Corima, Campagnolo and many of the Taiwanese rims have a pure carbon surface at the brake track and you will need to use a cork pad so as not to damage the rim.
The cork pads are soft and have a low coefficient of friction, but will not damage the all carbon surface. For more aggressive braking a stock Shimano or Campy pad can work, but these contain abrasives such as aluminum oxide which can damage a pure carbon surface (aluminum oxide is the stuff they make sand paper from). Campy and Shimano pads will not damage a Zipp rim as our surface is very hard, but the Campy pads specifically are so agressive that they generate excessive heat and can melt, leaving melted brake pad on the rim, which is almost worse than wearing the rim out as the melted pad material can cause brake pulsation and can be very hard to remove.
Our pad is thermally conductive for lower temperatures, and will not melt, so it is very safe for any carbon rim, and works well on aluminum rims. Our pads also will not abrade your aluminum rims making them last longer, but for most any other carbon rim you are really safest to use cork which is completely non-abrasive, but really doesn't work well at all on aluminum rims.
Index Categories:
Carbon Construction – Carbon clinchers vs. aluminum clinchers
Carbon Construction – Braking concerns with carbon
From:
JAG May 8, 2006, 6:47 AM
Question:
Composite brake pad recommendations?
I have a set of Reynolds DV/UL tubular wheels. Has anyone had experience with a good pair of brake pads that work well with these wheels? I am wondering if those red Corima pads are a good fit?
Josh:
Each manufacturer uses a different brake surface so you will find different solutions to each. Corima for instance uses a pure carbon surface with no brake surfacing, so only cork can be used as any other material will abrade through the carbon, especially when most stock brake pads contain aluminum oxide (sandpaper grit). The Cyclingnews.com guys seemed to have great results using Swisstop yellow pads on the Reynolds wheels, and I notice lots of the Pro guys that Reynolds sponsors using those same pads as well as cork. They also tell me our pads work well on Reynolds rims, but I haven't tested this in our lab so I'm not sure.
On our rims, the Swisstops look and work great, but our rim is considerably lighter at the perimeter than the Reynolds and when Phonak originally started using our wheels they had been using Swisstop and found that the yellow pads would melt onto the rims during high speed decents, very similar to what a Campagnolo pad will do (lighter rims get hotter with same energy input). So we still recommend either the Zipp pad or cork for Zipp rims. Cork pads are always safe because they are completely nonabrasive and do not generate heat due to their low coefficient of friction (they also don't stop so great, but that is the tradeoff). The Zipp pad contains highly thermally conductive carbon fibers to make is function as a heat sink and transfer heat into the brake caliper.
Overall, I would consult the manufacturer before using any pad as I know that some companies will not warranty use with some pads.
Index Categories:
Carbon Construction – Carbon clinchers vs. aluminum clinchers
From:
erwinchang Mar 28, 2006, 7:31 AM
Question:
Use special brake pads on Zipp Clinchers?
Does anyone know if Zipp clinchers require different brake pads than normal? The Zipp website mentions that their wheels should only be with carbon specific brakes (Zipps, Koolstops) but I was not sure if this was only applicable to the tubular wheels. Thanks for the help!
Josh:
No special pads needed for your 404 clinchers, but we do recommend the Zipp pads as stock Campy and Shimano pads contain aluminum oxide, this is the same stuff they make sandpaper from and will both increase heat at the rim surface during braking as well as shorten rim life by effectively sanding the rim every time you use the brakes. The Zipp pads will both reduce temperatures and increase rim life on any rim, be it carbon or aluminum.
Index Categories:
Carbon Construction – Braking concerns with carbon
From:
bikerbrian Jan 20, 2006, 3:37 AM
Question:
Carbon Tubular Breaking Surface?
I'm new to the world of carbon wheels and was wondering about the braking surface of these wheels. I know you need to use special pads and that breaking will not be as good but my question is this, is there any problem with the brake surface wearing down? Carbon wheels seem sort of fragile to me and it seems like this could be a problem. I don't have any experience but wanted to get some opinions before paying an ungodly amount for some Zipp 808's. Any help is appreciated, Thanks in advance
Josh:
From a data point of view, the braking of carbon rims is very specific to the manufacturer, so you will generally be best to do what they recommend. Our silica ceramic surface is actually slightly more agressive than aluminum when dry and about 96% as effective when wet when using the specific Zipp pad. Many rims like those from Corima, Campagnolo and many of the Taiwanese rims have a pure carbon surface at the brake track and you will need to use a cork pad so as not to damage the rim. The cork pads are soft and have a low coefficient of friction, but will not damage the all carbon surface. For more aggressive braking a stock Shimano or Campy pad can work, but these contain abrasives such as aluminum oxide which can damage a pure carbon surface (aluminum oxide is the stuff they make sand paper from). Campy and Shimano pads will not damage a Zipp rim as our surface is very hard, but the Campy pads specifically are so agressive that they generate excessive heat and can melt, leaving melted brake pad on the rim, which is almost worse than wearing the rim out as the melted pad material can cause brake pulsation and can be very hard to remove.
Our pad is thermally conductive for lower temperatures, and will not melt, so it is very safe for any carbon rim, and works well on aluminum rims. Our pads also will not abrade your aluminum rims making them last longer, but for most any other carbon rim you are really safest to use cork which is completely non-abrasive, but really doesn't work well at all on aluminum rims.
Index Categories:
Carbon Construction – Braking concerns with carbon
From:
????
Question:
What’s so special about Zipps brake pads?
The short answer is they disipate heat better and don’t have any abrasives to shorten rim life. The long answere is we worked a deal with the fiber supplier for a company called Hitco, who makes the carbon/carbon rotors for F1 cars. The base fiber for an F1 brake rotor is a highly graphitized (nearly 3 times stiffer than PAN based 'medium modulus carbon') carbon material called mesophase PITCH carbon fiber, it is also very expensive (~$400/lb for the virgin material used in the brake rotors), but when they stack their plies, and cut them into discs, they have all these corners left over. We buy the off-cut corners (for less than $400/lb) and have them chopped into a specific length and then added to the resin during the pad molding. The upside of mesophase PITCH carbon is that it is very light, and has very high thermal conductivity (copper is roughly 400 w/mK and this material is over 900 w/mK!!!), so whereas a basic brake pad will have thermal conductivity on the order of 2 W/mK, the Zipp pad with 20% PITCH material has thermal conductivity of 20-25 W/mK.
This is also why we don't recommend using carbon pad holders with our rims or pads...the pads can conduct heat very well, but a carbon pad holder doesn't allow the pad to transfer the heat into the caliper. The best pad holders are Campy or Shimano as they have the wheel insertion fins on the bottom, that in our case now serve as cooling fins. If we had to buy virgin PITCH carbon material for these brake pads they would costs nearly $100 per pair at retail, so it is only through our former auto racing business and contacts that this product is even possible. No doubt that the pad can be improved (and we're working on it) but at this point these are the most highly researched and designed brake pads anybody has ever manufactured and unfortunately most people think that they are just the normal KoolStop black pads since we can't add any cool colors to them or anything as the carbon material makes them very black (normal black brake pads simply use carbon black powder for their color).