Rear wheel wobbles during descents/general wheel question

[neilkod]

I have a CF(specialized tarmac) bike, Mavic Ksyrium Elite wheels. As I'm learning to descend more aggressively, I'm noticing that my rear wheel has a noticeable 'wobble' as I pick up speed. The wobble is much more pronounced when I'm in the drops. I have to hold back on my descents because I think my bike is about to fall apart!

When the bike is on the repair stand, the wheel 'appears' to be true and spins freely without any wobble or rubbing into the brake pads. I only notice this at high speeds.

Is something wrong, or is this just a part of descending?

Also, how does one know when your wheels are stiff (or not stiff) enough?

 

[RelevantAaron]

I have a CF(specialized tarmac) bike, Mavic Ksyrium Elite wheels. As I'm learning to descend more aggressively, I'm noticing that my rear wheel has a noticeable 'wobble' as I pick up speed. The wobble is much more pronounced when I'm in the drops. I have to hold back on my descents because I think my bike is about to fall apart!

When the bike is on the repair stand, the wheel 'appears' to be true and spins freely without any wobble or rubbing into the brake pads. I only notice this at high speeds.

Is something wrong, or is this just a part of descending?

Also, how does one know when your wheels are stiff (or not stiff) enough?

It is just part of descending, nothing sounds wrong with your equipment. I have a carbon LeMond with DuraAce wheels and the wobble usually comes in at around 45mph. The cure is simple - gently press your knees against the top tube and it will go away.