Just got a replacement Kestrel RT1000 frame. The headset/head tube, and steering tube is the new design. The steering tube has a larger diameter at the fork end and tapers to a standard 1 1/8" at the top. The FSA headset (that comes with the frame) also has a larger diameter bearing race to accommodate the bigger steering tube diameter, and a standard bearing race to fit the top of the steering tube.
I assembled it according to specs, tightened it just enough that there was no movement when the brakes are locked and the bike is being rocked back and forth. There is also no resistance while turning the handlebars, so the tension is correct.
Thursday, we rode a long, hilly ride. Four climbs and descents in excess of 2000' The downhills were pretty bumpy. Speed control and brake modulation was required as the pavement was less than ideal, the grade was 9-12% average and there were several hairpin turns. On the downhills, I noticed no creaking. On the last two climbs, the headset started to creak. Checked the headset tightness by rocking the bike back and forth with the front brake locked. No movement. Also, no resistance when turning the handlebars.
When I got home, I tightened the head tube slightly. No change. I then disassembled the steering tube and bearings and re-assembled to specs. The problem is gone.
Anybody have any idea what caused the creak and why it went away with just a simple dis=assembly and re-assembly? Never had this problem before. Could the headset be bad? I have not had good experiences with FSA headsets in the past. Just visited the Chris King site and they are making headsets for tapered steering tubes. Might be the way to go.
2003 Specialized Hardrock, 2004 LOOK KG386i, 2005 Iron Horse Warrior Expert, 2009 Pedal Force CX1
As I found through a somewhat similar experience, adjusting headsets that use cartridge bearings is quite different than a headset that uses loose bearings. The latter can be adjusted as you have already done, adjusting just until the play is gone. Cartridge bearing headsets are better adjusted by tightening until the steering becomes tight then backing off until the tightness is gone. This point will be far tighter than the point where any play is gone. That your creak temporarily disappeared means nothing. It will likely return in a short time.
When I assembly parts, I usually wipe the mating surfaces to remove any grime, dirt that could interfere with solid interfacing contact. Not sure if this is the case with your situation, but if it acts up again, give it a good wipe with a clean towel.