Perhaps you could add another entry for some special parts that were not mentioned above, e.g. crank bolts if weight is given w/out them or grease and stuff (difference between the weight of all single parts and the complete bike), so this weight can be added.
That's what those custom entries at the end of the page are meant for.
You can define up to 5 custom entries and modify them to your needs.
For a custom crank set crank fixing bolts and chainring bolts are still missing, I know.
I guess I'll have to split the bolts category up to fix this.
And a line for additional information (special features, alternate tires, type of use, e.g. CC, road, triathlon...).
Yes, I will add additional fields like this.
An advanced feature could be to choose the groupset and then modify the components you have changed.
I really have no idea how to include such a feature.
It's almost impossible to add group weights, since there are so many parameters to think of - crank arm length, BB axle type, chainring toothcounts, cassette toothcounts, different hub types, brake type, STI or separate shift/brake levers and so on.
Where do I find the weights for bikes?
Bike weights for complete bikes encounter the same difficulties.
One bike is not like the other, a +/- 200 g difference on a 10 kg bike is easily possible.
Not to mention manufacturers who change the specs of their bikes during the season.
I already get enough "the weight you listed can't be true, mine is much lighter/heavier" emails, I'm not keen to get even more.