The road bike has developed a squeak since its last ride on Sunday. Seems to come only when significant pressure applied on right pedal while spinning away. Without special tools it looks like the things I can try are to take off the pedal, clean, grease, refit. Should I undo the Ultegra SL ’08 crank bolts on the left crank where it fastens around the BB – clean, grease??, refit? Any advice much appreciated for this dark side mechanicking beginner.

Could be the chain, also are your cleats in good nick?

Ooh? Could be:
1.Cleats worn
2.Pedal bearing dry/play
3.Shoe just catching the crank arm at higher cadence (my heal twists at higher cadence resulting in the edge of the ball of my foot rubbing the logo’s off all my cranks!)
4.BB cup dry bearing or incorrectly torque into frame
5.Give up visit local bike shop 😉

You using SPDs on the road bike – mine creaked badly with my Specialized shoes – had to cut away a little of the tread around the cleat to cure it.