How many square inches or yards of fabric do I need for 1 frame bag?

[isignay]

I'm currently compiling a list of things I need for an attempt at sewing my own frame bag.  My gf already has a sewing machine and heavy duty needlees.  I wanted to know how many square inches / feet / yards of fabric I need to buy.  My local hobby shop / arts store does not have the heavy duty fabric I'll be using so I'm buying online, but I'm new to this and don't want to under buy what I'll need.  Also How long of a zipper / zippers should I buy, 2 feet?  1 foot?  Are the zippers adjustable or pre set in size (stupid question?)?  Thank you!

[cavscout]

Most of your questions will be answered when you make the template of your bike.  From that template you will be able to actually measure the size zipper, length of the gusset, as well as actually seeing where your zipper will be placed and where your velcro attachment points need to be.  I wouldn't bother buying anything until you make the template and have your design worked out, unless you find a great deal on fabric like I did in the group buy here on the forum.  This is one project where planning is very important in order to not end up with a bag that doesn't fit or work as well as you would like.

In general though, I'd get at least 2 yards since the gusset will likely be about 50" - 60" long and ideally that would be one continuous piece if you are making one large bag.   Plus, if all goes well, you'll probably want to make some other stuff later.

[isignay]

Thanks!

[jeremy11]

fabric can generally only be ordered in 1 yard increments, and 50 - 60 inch width.  even for a large frame bag, that will be enough.  add in a couple feet of continuous coil zipper, #8 or #10 size, enough velcro, good poly thread, and you've got it.

if you really want the exact fabric area, its back to high school math:
area of one side panel = 1/2 * (top tube length) * (perpendicular distance from top tube to bottom bracket)
area of tube panel = (3.5" or whatever width you pick) * (triangle perimeter)
total area = 2*(side panel area)*(tube panel area)

but I've never calculated that number, at least not in a very long time.  The thing that matters more cost wise is how you lay out the pieces to minimize scrap.