Originally Posted by
jdon
This is probably correct but unusual symptoms should never be ignored. I did have a drug reaction that manifested itself in the same way and with sudden and severe leg cramps. Once you got off the bike they almost immediately went away. This is a known side effect of the drug. Rare or not, it is possibly ( Note the first word in my response to the op) the cause.
My point is that this is an Occam's Razor example. I suspect that the examples of adverse drug reactions to Claritin D are not happening to people after several hours of exercise, rather than under more sedate conditions. Of course, being the internet we should encourage the people not listen to either of us and should talk with their real life physician, but I still think that more miles in the legs is the prescription in this case. The OP has got a nice weekly routine going on, but 6months isn't *that* long for the body to adapt to longer distances in all reality.
Other points to consider for cramping are cleat position and whether you are riding with your toes pointed down - this last one is common and effectively keeps your calf muscles into a contracted state for long periods.