I am building a small indoor wall at my work and have just bought a climbing hold set. The holds are small which means that i will be crimping for most of the moves. How effective is crimping alone in improving my climbing strength?
It will make you stronger at crimping. If you open hand them it will make you better at open handing. Anything else (power, technique, undercut strength etc) depends on how you set, how steep the board is, and so on.