Cheers for the replies,

I have neglected stretching really, most of my biking and some of my running tends to be commuting so I get out the door and just bike or run, pretty much the same at the other end.

I've been trying the stretches after biking for the last couple of days (to the amusement of my colleagues!), going for a run later - I'll see if the hamstrings are any easier.

Also, ride at a high cadence, so that the hamstrings and quads don't bulk up too much... riding at a higher cadence is better x-training for running.
What would you consider a high cadence - I reckon I ride about 80/min at the moment - is that high enough?