-Is it because fewer women cycle generally (and why is that?)
I think yes-and-no.
I say that because a lot of "round the world" types do it with negligible cycling background. It's more like
"
I want an adventure. A long one.
How about Round the WORLD??
How can I do that, at low cost ... hmm, it'll take years to *walk* it .... so how about ...
A bike?!! Yes!.
"
This is very true. Many, probably most RTW tourists will actively avoid the 'cyclist' label - because cyclists are lycra-wearing leg-shaving racer types who get pampered in hotels every night, don't know what real endurance is and are probably gay, right?
Our hardy adventurers who are using a bike for this trip, on the other hand ... well, their non-cyclist status probably explains a lot of the odd kit choices I've seen - usually involving packing far, far too much.
Here are some remarks I've had while touring:
"Why are you touring on a racer?" (This was a trad steel tubed tourer that happened to have drop bars.)
"Wow, you even look like a cyclist!" (Just after the wind had got up and I'd donned arm warmers and gilet. Errr yes I'm a cyclist, I'm riding a ... bike?)
"Lycra, that's a bit too professional isn't it? (Come on mate, you've just ridden from England to Vietnam, I'm sure you've earned some comfortable cycling gear. Many long distance tourists will resolutely shun any bike-specific clothing though, because that would be crossing the cultural divide and becoming 'cyclists'.)
"Where are you going tomorrow?"
"Chartres" (about 70 miles)
"No, but where are you going
tomorrow?
"Like I said, Chartres"
[Sound of someone who has ridden several thousand miles but not yet come to terms with the idea that even if he doesn't ride that far far in a day, it's a perfectly normal distance that a lot of people ride]
So yes, there's a big two cultures thing going on. I'm not trying to be nasty, I think it's great if people have the courage to ride round the world on minimal prior experience - though I do despair a bit of people who can't cope with the "cyclist" label after they've ridden a bike 10,000 miles. My point though, is that asking why group X aren't habitual leisure cyclists and why they aren't long distance tourists, are largely two different questions.