I lucked up and had the day off today. I decided I was going to do an impromptu solo century. I am pretty new to cycling (since April this year) but rode my first century in June (very slow time) and do a couple 100k's a month.

My normal ride is a 32 mile loop with 2 short but steep climbs usually averaging 19-21 mph. This is my mon, wed, fri, ride with either another lap on the weekend or a longer ride if I have the time.

I started out at about 11:00 today. The temp was 54*. I wanted to improve my century time but decided to start slow and build up the pace as I warmed up. I started great! The first 60 miles went without any problems at and I was keeping an easy 18 mph pace and really enjoying the ride. Then like someone flipped a switch the cramps started! I wasn't tired, I had no problem pushing the pedals just couldn't stop cramping! Several times I had to veer off the road and nearly crashed trying to get off the bike! The odd thing is as soon as I got off the bike and sat down the cramps would stop.

The only thing I can think of that may have caused this is I recently started taking clairitin D and was wondering if anyone else has had any issues with similar medication, or did I just have a bad day?