Once the stem is tightened in place is is purely cosmetic and covers the top of the steerer.
Road bike top cap torque.
In other words a torque wrench set for 100 in lbs might tighten to 96 in lbs or 104 in lbs.
If the motion of the bars feels sticky or hesitant loosen the top cap 1 8th of a turn and test again.
Next straighten the handlebars.
Test the headset adjustment by lifting the bike and pushing the bars back and forth the bars should turn freely with very little resistance.
Do it right use this torque guide.
Same is true for the end cap on a shimano hollowtech ii crankset.
The bung shouldn t creep up the steerer if is installed properly using carbon paste.
Torque wrenches available to general industrial work including bicycle work are typically accurate to plus or minus four percent.
A torque table for bicycles.
Don t over tighten nuts bolts.
Here s how to do it.
Tightening your headset is one of the most simple pieces of bike maintenance but it s also very important.
Gazelle trading 1 1 8 inch bicycle al alloy headset top cap bolt mountain bike stem top cap cover headset screws for mtb road xc fr bike stems 3 8 out of 5 stars 10 10 98 10.
Snug the top cap down until there is slight resistance.
It is non load bearing.
You want the minimum torque to reduce play in the headset.
As others have said the top cap is pre load only.
Once the stem bolts are then tightened the top cap torque is irrelevant.