The annoying rattle...

[Sleeper]

Yep. Driving me nuts!! Any suggestions on this welcome...
Just rebuilt, all new components, just the frame and seatpost remain. I would say this is a loosening up rattle (?) as done about 250 miles so far. The rattle happens when the bike is 'warm' (I know it sounds ridiculous) I.e. after a mile or so it slowly appears. Sounds like it's coming from the front brakes/hubs (mech discs, spotlessly clean) however when out of the saddle the rattle seems to be coming from the BB area?!? I've checked cable ends, frame sections, chainring bolts, disc bolts, headset tightness (all nicely solid), basically everything!
First few runs she was absolutely silent, please help!
B

 

[rusty bearing]

Lets try to narrow it down a bit. Is it a rythmic sort of rattle or more random , perhaps showing up more on rougher surfaces?

 

[Sleeper]

it's consistent, doesn't follow the crank rhythm if that's what you're asking? All my roads here are rubbish (!) as several years of 'spray and scatter' resurfacing starts to break up. FYI I'm running Schwalbe Kojaks at 90psi which feels very firm with minimal give

 

[rusty bearing]

When you rebuilt the bike did you put new bearings in the hubs?

 

[Sleeper]

Starting to think 'rebuilt' should be 'built', but yes, brand new wheelset - FSA XC105's with cartridge bearings. I'm familiar with cup-and-cone, do you think they may be loose? They run smoothly, silent on the stand and withno play...

 

[baznav]

Check the bottle cage bolts are tight if you have them.

 

[heliphil]

I remember a coaching session and one of the youngsters bike's had a rattle - turned out to be a small plastic clip on the saddle, had some of the experts mystified for a while....