How to split TrueCrypt file into smaller files for cloud backup to OneDrive?

TrueCrypt is not suited to such a large volume of data coupled to a 2GB file-size limit.

You should be looking at solutions for directly encrypting the OneDrive data. This way you will avoid the need to upload humongous files to OneDrive, just uploading the files that have changed.

Here are some products that do just that (in alphabetical order) :

Boxcryptor
Cloudfogger
nCryptedCloud
Viivo

There is not a way for Truecrypt to do this. What you can do to make it a bit more effortless is to RAR the TrueCrypt volume into 2G pieces without using compression. This will make the process fairly quick.

WinRAR has a command line interface (rar.exe) which you could use to write a batch script to make the split and concatenation of the TrueCrypt volume. You could even use TrueCrypt's CLI options to automatically mount the volume after the concatenation.

Example commands:

# Split a file into 2G chunks and don't compress
rar.exe a truecrypt.rar truecrypt.tc -v2000m -m0
# Extract it
rar.exe e truecrypt.part1.rar

# Mount truecrypt volume
truecrypt.exe /q /v X:\
# Unmount truecrypt volume
truecrypt /q /dX 

Put these commands in two seperate batch files (umount and rar and extract and mount) and make sure the file names end with .bat. You can then run them by double-clicking.

Since you want encryption for your cloud-stored files you could also use EncFS. It encrypts every file separately and stores it in a folder of your choice. I have succesfully used it together with OneDrive, Dropbox and Wuala.

With EncFS you get an unencrypted view of your files as a Drive (in Windows) or a FUSE mount (in Linux). The encryption/decryption is done transparently. Each of your files or folders results in an encrypted file or folder. (You can set that the file and folder names are also encrypted)

There is also a Windows version and several Android versions.