+1 for the hardtail commute fun bike deal thing derp
.
I used to do the school run on an STP, wicked fun compared to a dually. Every curb becomes a massive jump you can really pop off and practice popping off lips as oppsed to just ploughing over them. Really easy to ride in comparison (even single speed), lighter, faster to accelerate, easier to bunny hop / 180 / whatever. Not to mention you wear out your DH bike less, chains, cassettes, shocks will all last longer if you're not using it daily. Not to mention the rolling resistance on something like minions (Sprint, get to speed, relax, lose all speed after like 20 meters, repeat). Now I do some commuting (the occasional ride to work I guess when I'm not feeling lazy ... which isn't very often) on a flat bar road bike. Less effort gets me to work faster and with less dying of exhaustion. But if you want to ride the DH bike, just do it, best case scenario you'll meet a fellow rider who'll be like, sick glory dude lets go shuttle aye
. Worst case it gets nicked, but if you've got decent lock / insurance / don't lock it up in a poorly lit alley, this risk is minimised. My guess is like the other people have said, people don't usually see DH bikes around. I mean i've had mates over, who know I ride, come and look and my bike and basically go 'shit, it's a moto without an engine isn't it?'. Like they can't comprehend a pushbike that's just so badass
.
So to answer your question, yes, you always need another bike (I've settled on 4 as the ideal number now personally
, being DH shuttler, a DJ, commute bike & an all mountian / xc / trail whatever bike which is currently a norco truax for my fat ass-ness). The world opens up once you get more than one bike
.