It's not my legs - they are OK, as the lack of freehub means once I've got some momentum going, the pedals seem to get turned round at a fair whack anyway which saves any painful grinding - the gear is pretty small. It's my lungs that may burst on the long-ish hill as I won't really get the usual option to go any slower - or at least, not without it hurting my legs! I suppose I have the option of either turning the pedals more slowly, meaning less gasping for air but more pain, or, faster pedal rotation, meaning less pain but more danger of exploding lungs....
Regarding cadence - It's interesting: 'practicing' for fixed, by spinning a smaller gear than usual yesterday I acheived a higher speed than normal. Today, even though I was deliberately taking it easy, I wasn't really any slower than usual either, so I reckon that contrary to what may seem logical, faster spinning of a slightly smaller gear, actually equals faster cycling, not slower! I think many people don't realise how over-geared they are and turn a slightly too large gear, thinking they must be able to go quicker like that, than if they changed down a gear, when in fact, they aren't - not unless they really are very strong and able to turn it quickly enough.