What would be the theoretical maximum spin-rate of a small asteroid (25 - 100m diameter?) if it were, for example, composed of a single 'monolithic' chunk of iron? 

 This question arose after reading up on the subject in a Wikipedia article. Listed in it is one such asteroid with a spin-rate of around 30 seconds. Could this be bettered, given the above parameters? 

Many thanks.

https://en.wikipedia.org/wiki/List_of_fast_rotators_(minor_planets)

In theory, the only limit would be that due to relativity

1 hour ago, mathematic said:

In theory, the only limit would be that due to relativity

...material strength vs centripetal force?

It's impossible to say what the max spin rate would be. It depends on the mass, the shape and the material, and probably other factors. 

You also have the problem of what could make it spin. It would generally be a collision with something similar. And the higher the spin rate, the more violent a collision is needed. So there will be a limit, beyond which the thing would just shatter as they collided.