Bicycle Mechanics - No star nut=loose fork?
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I'm assembling my 1st bike, so I'm slightly paranoid about adjustments that I don't normally do. My "problem" right now is the headset (integrated).
I haven't yet cut the steerer to correct size. Hence, no star nut yet.
When I put the 2 sets of bearings over the steerer, they both seemed to have some play. The outside diameter is fine, the bearings sit well inside the headtube. However, without preload, the fork seems to rattle, even if I tighten the stem nuts while pressing down on the stem.
Is this normal? Will installing the star nut (eventually) remove all this?
The cartridge bearings used in integrated headsets have some play on the steerer. They hold the fork by engaging angled surfaces that mate to the inside angled surface of the bearing. On the lower bearing, this angled surface is on the crown race. On the upper bearing, the angled surface is on a compression ring that is stacked on top of the bearing. The compression ring should be a tighter fit on the steerer than the bearing.
Due to the angle of these bearing engagment surfaces (about 45 degrees), there will be significant play in the headset until preload is applied.
So, yes, this is normal and by desgin, and preloading the headset with the top cap should remove the play.
02-14-08, 11:57 AM
Install the star nut and stack a bunch of spacers to the uncut steerer tube and see. The start nut can always be driven down further later on before cutting the steerer tube.
I kind of thought so.
The crown race does have angled surfaces so I COULD imagine the bearing could be pressed against it. However, the top bearing, even with the compression ring in place, still has a bit of play. The rings slips in easily and I can remove it with my fingers without any effort.
That's mainly why I was suspicious.
02-14-08, 05:33 PM
do not put a star nut in a carbon steerer, if that is what you have. use an expander/plug.
I know that.
Steerer is alloy.
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