What happened was someone (a politician most likely) said "we need to hire these bikes out to look as if we're doing our bit to offset carbon emissions".
Someone else – a politician said "If it's too cheap no-one will use the tube or bus. And in turn, no-one will by petrol at £1.08 a litre. Which is very bad indeed".
Another politician said "Better put a disincentive in place for people not to use these bikes then!"
Billhooks. £50 might be a reasonable amount to hire a £3k Yeti for a weekend, but for Joe Public it's a disgrace. I'm all in favour of more Londoners opting to cycle (I'd go so far as to say that cycling around a city centre should be a compulsory element of a driving test), but I cannot and will not abide a £50 surcharge. End of.