After years of working in the finance industry I would advice against even the 0% credit stuff.
Open an easy access account with the Yorkshire Bank put in what you can each month/week and spend it as it accumulates sufficiently, easier said than done I know.
Do you work for the Yorkshire Bank ??
With half decent bikes costing silly money these days, you either have to save up for a very long time, or use 0%
The last bike I bought I paid £2,500. (bloody stupid when you can buy a decent car for less) Paid it off 0% over a year. The bike will have to last me probably 8 years + as I can not justify paying that much money on a bike for any less.
I wouldnt have wanted to be without a bike for the year while I saved the cash.
collectively sufficient people will be defaulting and paying a exorbitant interest to make lending to the others profitable
If people can not manage their finances, thats not my issue, and if it enables me to get cheap credit, then fair enough.
However from a society point of view, it is generally the vunerable and less well off people who pay the most for credit.