Re: Donating bikes for charity
You could enquire of Hiob.ch, though they would probably not have the funds/staff to collect them. If you've the energy to take them to a Hiob Brockenhaus (2nd hand charity shop which sends bicycles to poorer areas of Eastern Europe, or something like that, I think) you could do so by train, at Fr. 12 per bicycle (plus your own fare, of course). That might work out a lot cheaper than the municipal fees for really throwing them away. And thanks for not wanting to do that.
Or take them to a refugee centre. Remember that the refugees, too, would probably not have the train-fare to come to collect the bikes from you.
Or if your focus is that you really, really want them collected (rather than the focus being that they go to a charity), you could advertise them for free, to give away (gratis zu verschenken) on fleedoo, tutt, in gratis-inserate, in couchsurfing... or on this forum.