Sorting problem

Hi
I'm trying to help a colleague with a wbs challenge they have.
They want to show data in the following way, but the Sort function in Excel doesn't work properly with this if you try to sort using the WBF column. Looking at this example, the ultimate parent would be 1=Frame, below that you have 1,1=Headset (part of the Frame), then within the Hub you have 1,1,1=Headset Bearings......etc. Hope this makes sense and someone can suggest how this can be sorted numerically. Is there a different way the information in WBF column can be displayed that would sort properly? Incidentally in case you can't see the screenshot below properly, WBF is Col A with numberical values separated by Commas......Bike Item is the text description (Col B), which relates to corresponding numerical value in WBF Column.

Thanks
Wendy

WBF Bike Item
1 Frame
2 Wheel
1,1 Headset
1,1,1 Headset Bearings
2,1 Hub
2,2 Spoke
2,2,1 Spoke Nipple
1,2 Bottom Bracket
2,1,1 Cones
2,1,2 Hub Cones