I wouldnt worry about that. Quads are larger than hams, so your quads will naturally be stronger. Your bis and tris would be more comparable, but one muscle will usually always be stronger than the other just because of your genetics. Large muscle groups are stronger than smaller ones. The main thing to keep things well rounded is to stick with compound exercises. For instance, Squats work out your entire legs. Back works out your bi's naturally because of the pulling movements, and Chest work gives your tri's a workout because it is a pushing movement. Dont compare muscle groups too much to eachother. Just keep the basics down, and go heavy and hard on them.
I think a better gauge to tell if your muscles are up to par would be if your back and chest workouts are making progress or if they have been at a standstill. The culprit could be your weaker biceps or triceps. If your making stead progress in both those areas, your probably doing ok.
Good luck.
