The original plan with the London scheme was to avoid docking stations at railway stations as these encourage commuter use. The problem with commuter use is that there is a strong 'tidal' flow in the morning and evening rush hours that mean there is too much demand for bikes or spaces near the railway stations / workplaces. It requires siginificant intervertion to counter this (bikes being shifted on trailers). It may be therefore that in York, the decision is deliberate.
As far as trialing a scheme with only a small number of bikes is that there is probably a critical mass effect. If too small (as, I would suggest, 130 bikes is) the reliability of bike availability is too poor for people to use them routinely. It will mean that only opportunist ad hoc riding is likely to take place, which won't bee a good indicator of the full potential uptake.
