Jscan

Not sure if this is the appropriate forum, but I'm currently prepping for a solo, southern tier coast-to-coast ride that I'm embarking on in May. Like my last little tour, this will be on a tight budget, though more practical than the 50 dollars i had last time.

I confidently plan on using my cheapo schwinn rear rack that does not have pannier supports, and this is because I'm riding my rebuilt schwinn varsity 08 (the cheap wal mart one). This frame has no holes by the rear wheel mount for a traditional rear rack, and I fully intend on using this frame for the trip. My question is, are there pannier-supporting side bars I can add on, and if not, what is the risk and feasibility of just making one out of parts from a hardware store, that may include drilling through or screwing into the aluminum frame?