I have an idea... Is it possible?

So, I am new to arduino, and these forums. I have been thinking about an idea for the past year or so, and my wonderful wife got me an arduino kit for Christmas. I don't know if the arduino and it's supporting parts/accessories can do what I am asking. I did some searching on here, and could not find an answer so I figured I would ask here. I am wanting to convert my bicycle into an electronic shifting bike that can do a whole lot more. In know that there are companies that make electronic shifting, but buying isn't as fun as making. So, aside from the parts needed to complete it, I need to know if the arduino is capable of pulling in two inputs for shifting (1 for shifting each direction) to control the dérailleur, 2 inputs that can also effect the derailleur and send info to an ldc to display current bike information.

Its certainly do-able.

Its not the concept thats hard its the doing.
You need to ask a lot of questions.

What are you going to use to operate the actual shift ?
What voltages are needed for each part ?
Can you make some of the parts yourself or do you have companies that can ?
Can you override it and go back to manual ?

I am sure you will come up with lots more yourself and some of them might be no I cant do this or that at which point you need to look for a source that can and is that source going to cost you so much that its not worth it.

Simple concept but a lot of work ahead of you.

Thanks for the response. I am looking into most likely using a linear stepper motor to shift the derailleur, possibly a metal geared servo. I have drawn up ideas on how both will work. I don't know anything about the coding yet, but there will be 11 gear positions that I will have to figure out. I am going to fabricate the mounts. Voltages I am unsure about. I am thinking of using a 7.4v lithium ion battery that Shimano has for their electronic shifting bikes because it is rechargeable, and I can easily hide it in the seatpost. I dont know how to find out how much voltage is needed to power a system, but powered units include the arduino, motor and ldc. Everything else is just input switches basically. I assume that I need to calculate for power being consumed by those parts, the wires being used to transfer the power. I am designing this to be automatic shifting but I want to have a switch to turn it back to manual electronic shifting. Minus the coding and understanding of what the arduino is fully capable of, it mechanically seems very doable.

If you know what parts you need - sensors and actuators, for example - then you need to learn how to interface your Arduino to each item separately using short single purpose programs. Only when you know how to use every part should you start trying to build a composite program.

Maybe have a look at Planning and Implementing a Program