I have a new Jamis Sputnik fixed gear bike. When ever I go over a larger bump the headset (or at least it sounds like the headset) makes a vibrating sound. It doesn't make the sound on smaller bumps, but I have a fairly bumpy commute and it's driving me crazy! I've checked the headset (twice) and it's tight, there is no play in it at all. If I lift the bike up and drop the front wheel it will bounce and recreate the noise. I've never had a bike make this noise, and don't think it's normal, nor does it sound good. Could the headset be set wrong? Cheap headset? Is it normal? What's up! Any help appreciated.

*I found one other post which sounds like the exact same problem, I thought it interesting they also had the problem with a fixed gear.

Sometimes a headset will feel OK if you just turn it by hand.....Try applying the front brake and then pushing back and forth on the bike while holding your thumb on the stem or headset. If there's any play you should be able to feel it.
You might check the front wheel bearings while you're at it, though it certainly sounds like the headset. Fixed-gear should have nothing to do with it.

Did that and there is no play at all. I re tightened the top cap and stem and still making the noise.

check EVERYTHING- if possible find a pump in a quite road so you can look down when you hit the bump. it sounds like it might just be a brake cable housing slapping against the bar or stem? I had a creek like this that ended up being a losse front wheel quick release. I had another the other day- a humm on rough roads that ended up being a loose bottle cage bolt. I used to store a spare spoke inside handlebars til that rattle drove me just nuts. I guess my point is it can frwquently be the stuff you've never considered, so try virtually everything.

Are you using the little nut that come with a presta valve tube? Is it loose? Do you have any loose spokes?

Presta valve nuts are tight, spokes feel good. Housing isn't hitting anything. I have checked all common noise makers, nothing...

I'm still thinking it's some how the headset. I do have about 2" of spacers, could that be causing something?

hub bearings