Zipp 303: Black 'dust' on brake pads

I just bought a pair of Zipp 303 with powertap rear hub and DT aerolite spokes. Now, two questions:

1) After a 150km ride with 2 long descents (which means braking in the corners), there is an almost 1cm long build-up of black 'dust' on the brake pad. This has happed on 3 outings now, so it is not just some 1st ride effect. I use the zipp carbon-specific brake pads. What is this? Is it the brake pad wearing down, or is it my cherished new rims that are being worn like butter?

2) I had the impression of less stability above 60-70kmh compared to my old wheels (Easton Cirquit on Cervelo Team). Is this because the DT aerolite spokes are too thin? Is it because they are not tight enough? Or is that simply unavoidable because the zipp rims are light carbon tubulars compared to the aluminium clinchers I had before?

3) When coasting down-hill, there seems to be an unbalance in phase with the wheel rotation, which I guess could be the valve+valve-extension. Is this normal? Does there exist lighter valves? Should I glue something of similar weight to the opposite side of the rim, Or should I simply live with it?

Thanks
Henrik

I can only answer question 1. Yes, you are wearing down your new rims. This is an unfortunate consequence of making the braking surface out of a relatively soft and expensive material.

__________________
"All that we see and seem is but a dream, within a dream..."

and you'd be wrong in your answer.

It is the Zipp Carbon/Carbon brake pads wearing out. They wear extremely quickly.

In response to the OP's 2 other questions, what is your classification of less stability, can you explain it more?

With regards to an imbalance in phase with the wheel rotation, are you running tubulars or clinchers? With tubulars it is common for someone that is not comfortable with the gluing process that they don't get the valve area sealed down correctly.

So you really think that the braking surface doesn't wear?

__________________
"All that we see and seem is but a dream, within a dream..."

Well, the stabililty thing is subjective I guess. If pushing it on the descend (70-80kmh), I felt less comfortable in, say in fast 60-90 degree bends, particularly if road was a bit bumpy. That compared to the previous wheel, which was an aluminium easton circuit clincher.

I'm using tubulars (vittoria corsa cx). They were mounted by the bike-shop. He left about 5 cm of the rim without glue opposite to the valve, saying that it is easier to remove the tube then.

Thanks
Henrik

Of course they wear, but not nearly as quickly as the break pads.

__________________
http://jonathanlovelock.blogspot.com/

Of course it does - just as Jono says, not nearly as fast as the super soft Zipp Carbon/Carbon brake pads. You get the same effect in just a single crit covering 40km if there is a lot of brake action.

What PSI are you running in the tyres?

I guess I/we need some clarification because I thought the ZIPP 303 rims had an aluminum braking surface (is that right/wrong?), and I think everyone has responded based on a presumption that the rim is entirely carbon fibre ...

If the rims do have an aluminum braking surface, you can use a set of "regular" brake pads as your riding conditions (e.g., wet or dry) warrant.

FWIW. I (apparently) singularly believe that you want the stoutest (e.g., straight 14g) spokes on a wheel ... "soft" (e.g., double-butted) spokes provide an easier opportunity for oscillation.

303 rims can be carbon or alu. The tubies are only carbon. He's go tubbies thus the surface in carbon.

__________________
http://jonathanlovelock.blogspot.com/

THANKS for the clarification.

Either way. You should stop breaking.

__________________
Cake or Death?