Join Date: Jan 2008
Location: Spokane WA
Bikes: Giant OCR3, Marin Mount Vision, '94 Bontrager Racelite, Mirraco Blink
That is indeed where the rim is joined together, though in your case it is separating.
I'd start saving some monies for a replacement.
If you want to learn how to build your own wheel, here's a cheap rim
(make sure you match the amount of holes in the rim to how many holes you have in your hub). I've had good luck with Alex rims.
Then figure out the spoke length you'll need, there are several calculators on the internet
, or you can have a shop help you. You can find spokes here
, but remember, you need to find the correct length before you order.
follow Sheldon Browns
how-to for wheel building.
Wheel building takes time and patience, the most difficult part is getting the correct tension throughout the wheel.
It is very likely building your own wheel will end up costing more than a low-end off the shelf wheel, but you'll have the knowledge, and it is oh-so satisfying to build your own wheels!