Cramp

[montage]

Cramp tends to be due to an overall lack of condition, hence cramp threads are common early season and rare late season.
Electrolytes are thought to be involved but there's little real proof.
The usual advice is to drop a few gears and spin to take the pressure off the muscle.
Calves maybe partly due to pedalling tecnique, such as pedalling 'toes-down' which keeps the calf in a constant state of contraction and hence fatigue, try pedalling more flat-footed, you may need to drop your seat a tad.
On a TT, make sure you're 'pedalling circles' and maximising usage of all your muscle groups.

Gooogle cramp, you'll soon realise that although a common ailment, nobody really knows much about it's cause.

I'm no fabian cancellara but my condition isn't awful. Thinking about it, I'm pretty sure it could be the toes down thing, as I said I point my left foot down a little extra. As for pedaling in full circles, after experimenting a bit, I reckon that it's ok now and again to shift muscle groups, but a pulling on the upstroke is just bit of a waste of energy - for me

 

[Glover Fan]

I get a lot of cramp in my feet. However I have pretty much pinned it down to temperature, I hadn't had it for ages but on friday it was particularly chilly and after about 30 miles it came on again.

With that in mind; did you warm up sufficiently beforehand?