Murielax,

On another thought along with doing more base miles- if you all started out equal...

Are you shifting the same as them? In the same gearing, same rings? Are you shifting throughout your ride when winds or little uphills/downhills change? There is a good chance that you are just in the wrong gearing and not able to produce the same speed output as your friends.

If you are ever not busy and in town on a Monday evening, feel free to come out to our women's ride- we do a lot of work on the aspect of shifting and how it can help with your ability to maintain throughout the ride.