Does spinning make your thighs bulky?

The first day back to work after 4 days off is always tough. One nice thing is that the students are usually tired and not as rambunctious because they aren't used to waking up so early.

I was full of energy today, though and made it to my spin class tonight. Tough, long hills!  This may sound silly, but I have always had this fear that spinning will make my legs bulky.  Years ago, I searched for information about this and found it to be untrue, but I still can't help thinking that when I am chugging up those heavy hills, I am doing nothing but making my thighs huge!  Any feedback would be much appreciated.  Luckily, I only take 2 spin classes a week. I love the music and the cardio workout I get from them.

Today's workout: spin class 1 hour - 6 points  F&V - 1 point Total points for HBBC: 7