for all the piss-taking, there is a serious point here. Some of the patronising in shops thing isn't entirely sexism, as you do get the Not the Nine O'Clock news hi-fi shop thing with any vaguely techie item and a possibly not well informed customer coming in to buy a "gramophone" (grandad).
I'd also opine that the girls are on average rather less interested in pissing contests between record and dura-ace - which seems to figure in us blokes' thinking rather more - we're such shallow creatures after.all. Thus much of what goes in the till is driven by blokes who are kit oriented, and as there's arguably fewer girls in that category, there's less choice in good quality kit for the serious athlete ladies - whilst the serious athlete blokes benefit from the market fuelled by the wannabees.
Some of it might just be economics. Sales people tend to make snap judgements on customers based on stereotypes - my grandmother used to work in a jewellers and nearly blew a high value sale of a top quality gold watch by suggesting to a slightly scruffy customer that they couldn't afford it - a lesson she noted and passed on to me.
Ultimately patronising customers is poor selling, and being sexist to customers is plain rude or worse - but then the money will go into someone else's till.
Perhaps touring bikes are more equally covered with sizing options and types - and tourists of either gender probably know what they want so outfits like Thorn or the bespoke firms whoever are not as likely to patronise their customers.