1st frame bag

[mr clean]

Was fixing to pull the trigger on a revelate design salsa el mar frame bag when I realized that the tangle bag is different.  I'm thinking I will be using the bag on two different bikes depending on the journey and adventure I'm going on. I would like to use the bag on a salsa el mariachi and a surly cross x check. Is the salsa bag universal or should I go with the tangle bag?

[fotooutdoors]

Full frame bags are generally frame-specific, though similar frames can generally use the same bag.  The Tangle should fit both bikes, but the full frame bag will have a different shape than the triangle on a cross check, so it won't work the best.  That said, it may still be workable, but I personally would go with the Tangle if I were in your shoes.