Originally Posted by nfmisso

Rough numbers per the OP's request.

[TABLE="width: 146"]
[TR]
[TD]frame[/TD]
[TD="align: right"]17%[/TD]
[/TR]
[TR]
[TD]RD+FD[/TD]
[TD="align: right"]17%[/TD]
[/TR]
[TR]
[TD]fork[/TD]
[TD="align: right"]11%[/TD]
[/TR]
[TR]
[TD]shifters[/TD]
[TD="align: right"]4%[/TD]
[/TR]
[TR]
[TD]saddle[/TD]
[TD="align: right"]4%[/TD]
[/TR]
[TR]
[TD]seat post[/TD]
[TD="align: right"]2%[/TD]
[/TR]
[TR]
[TD]brakes[/TD]
[TD="align: right"]4%[/TD]
[/TR]
[TR]
[TD]brake levers[/TD]
[TD="align: right"]4%[/TD]
[/TR]
[TR]
[TD]grips[/TD]
[TD="align: right"]1%[/TD]
[/TR]
[TR]
[TD]hubs[/TD]
[TD="align: right"]9%[/TD]
[/TR]
[TR]
[TD]spokes[/TD]
[TD="align: right"]7%[/TD]
[/TR]
[TR]
[TD]rims[/TD]
[TD="align: right"]9%[/TD]
[/TR]
[TR]
[TD]tires[/TD]
[TD="align: right"]6%[/TD]
[/TR]
[TR]
[TD]tubes[/TD]
[TD="align: right"]2%[/TD]
[/TR]
[TR]
[TD]cables[/TD]
[TD="align: right"]1%[/TD]
[/TR]
[/TABLE]

For drop bar bikes with brifters, the shifter/brake lever combination increases to around 20%.