At Back2bikes we do not give refunds on bikes but allow people to trade up within a month We offer no warranty but will fix a bike within the first month if there are any issues such as brakes or derailleur slippage or any serious issues.
Regarding second hand parts we generally sell them to people who seem to be aware of what they are buying and explain that they are cheap and that it is buyer beware.
With new parts we abide by Australian law which states that the part must be fit for use. We generally offer to exchange or refund if the part is faulty or unfit for purpose.
I would make the comment that we are a self funding community organization so often our buyers are also donors. Our policy is therefore to err on the side of generosity particularly when dealing with clients who are obviously in need of assistance.
Geoff Back2Bikes Port Melbourne Australia