This is crucial for anyone serious about bicycling. I am always sad to see people riding bicycles too big or too small for themselves, and with the seat too low. Not only can this lead to problems like the one you experienced, it also makes the bicycle much less efficient, therefore harder and less enjoyable to ride. I always wonder how many people give up cycling because of this, when they might have had a much more pleasurable experience with a bike that fits them and is properly adjusted.