Sounds like both of you are trying to get into shape, not already in peak condition. *You'll both feel it after your long rides for a long time to come - you're on the right track. *At this stage in the game, I wouldn't jump to any conclusions about your form. *As a novice rider, I would sometimes fatigue my quads first, sometimes fatigue my hams first, and sometimes my calves would give. *Get strong, focus on muscle balance and staying in shape. *Form will come, and you'll have different from than your buddy. *That's just fine. *Unless your quads are chronically fatigued, or you're feeling non-muscle related pain, don't read too much into it.