GPS or phone app?
I am looking into using GPS for biking for the first time so first and foremost i just want to know what i should expect it to be capable of.
is there a good biking GPS phone app that people prefer?
If i have a PDF trail map that someone has made, can I somehow align it into a coordinate system and follow my path on a smartphone?
What smartphone do you have?
depends on the phone. depends on the app. I am unaware of any smartphone apps that can georeference a pdf file, or any file for that matter. Right now, the software to do that to pdf files is very expensive (it would become a GeoPDF) and right now only professionals are using it. To georeference it, the cheapest way would be to convert it to an image like a jpg or a tiff and then use Google Earth. GE does not give you the best transformation algorithms, but it will give you basic georeferencing capability. Beyond that, making use of it on a phone, I do not know.
Aside from that, there are a lot of phone app discussions in here already. Try reading those before investing time in asking questions.
There is an iOS app called Maplets. It will find maps in your area, or an area that you specify. Most, if not all of these are .pdf's. It will also show your location on the maps. It does have a disclaimer that the maps are not for navigation.
I find this to be a great app. It's nice to be able to find State, County, BLM, USFS, or even city maps of special use areas.
App store: https://itunes.apple.com/us/app/mapl...337841739?mt=8 It will cost you $2.99.
Website: Maplets - a comprehensive maps app for iPhones and iPads
There is also a cycling specific version that is only $0.99: https://itunes.apple.com/us/app/bike...401478553?mt=8
you may want to check MOUNTAIN BIKE PRO.. dunno if its what you are looking for but it can download maps of areas you specify and use it offline.