Maybe time for some facts rather than anecdotal evidence? :)
Both road cycling and mountain biking have the greatest gender difference of all active outdoor pursuits, with a ratio of approximate 2:1 (male to female) in relation to occasional participation. The gender difference extends to 3:1 (m:f) for regular road cycling and an even greater 4:1 for regular mtb’ing.
This is a much greater difference between male and female participants than other outdoor pursuits. There are equal numbers of men and women taking part in Snowsports (eg skiing etc), outdoor swimming, and hiking, and a mucher lesser difference in gender participation levels in running, climbing, and kayaking / sailing. The only active outdoor pursuit when the number of women exceeds men is horseriding.
The data and research that I specialise in indicates that getting dirty, not wanting to exercise etc are not the main reasons why women don’t participate more in cycling (although overall lower participation rates in all active pursuits are linked to lower levels of autonomous leisure time). One of the most intersting findings that I am currently researching is that latent demand for road cycling is greater for women, which bucking the standard user demographic profile and is very unusual.
Certainly, qualitative research is indicating that there is an ‘image issue’ associated with women’s response to participating in mtb’ing. The role of current mtb’ers and the media / biking industry undoubtably has a role in that image.