My bike has this red reflective light right below the seat (I don't know its name), and I'm thinking of buying a seat bag such as this one. Won't the light be covered? Isn't this potentially dangerous? How does one fix it normally?
It's a little sad that the bag doesn't come with a proper reflector, but a clip-on unit can be added, as suggested. The flashing red LED clip-on tail lights are quite inexpensive, will run continuously for a week or two on one set of batteries, and are well worth the investment, though make sure that there is at least some degree of passive reflector function in the clip-on and/or the cloth of the bag as well.