I'd say it was fairly big from my limited experience, plenty of mums, business men and students on mamacharis with umbrella holders, designed for daily use. As with everything in Japan the etiquette on a bike is exemplary, they ride on the pavements but everybody takes care, no city boys on carbon bikes trying to beat a strava segment like London. Obviously there is the Kierin, Rinko and a big (high end!) vintage scene too.
And Blue Lug is amazing, I spent an hour in there just wandering around picking stuff up, and then promptly putting it back down and considering my mortgage payments. That other place is right above the big Nike store in Harajuku right? If I recall correctly, it was called 'Pist' which I found fairly amusing.