Suggestions for a doggy backpack carrier (for the human to carry the dog)?

I’ve looked high and low on the Internet for a backpack carrier to carry my mutant rat terrier when I ride my bike or go for an extended hike.

Amazon and PetSmart both sell the Outward Hound Backpack Carrier, which looks okay, but Junior is too leggy to fit comfortably in it even though he’s under the weight limit (he’s 12.5 pounds).

The Teafco Action Petpack Carrier looks a little too rigid for biking or hiking.

I’d rather try one out at a local store than buy online, in case it doesn’t fit or suit my needs. (Returning online purchases can be a hassle.)

Any suggestions?