Hi,

When you are not confident on the transition time (rise time or fall time), you'd better drive your cricuit with a desired buffer.

You should consider which cell will drive the input (data or clock input). Then use that cell to drive your circuit. So you needn't worry the rise/fall time.  

By the way, the transition time of 130nm technology must be much less than 1ns.

Best regards,
Yawei