Motorcyclists face different problems from cyclists but they're often down to the same root cause; being a minority that's not understood by 'normal' people, i.e. drivers and pedestrians. We fall between the cracks in the rules, and just like pavement cycling some rules aren't often enforced; e.g. in some towns traffic wardens see no problem with a motorbike parked out of the way on the pavement as long as it's not causing an obstruction, while in other areas it's a guaranteed ticket.
Parking for motorcycles is rarely signed and even when it is, the signs don't follow any common standard. There's also inconsistency on charging; here in Blackpool, we can park in a car space if we buy a ticket but the council's advice is to keep the ticket in our pocket rather than display it so that we can produce it later if we get a penalty. Other councils are less flexible, or simply ban motorcycle parking from car spaces altogether. (As well as security, there's also the issue of a bike's vulnerability to damage; I was recently without my bike for two months after a driver rammed it in a supermarket car park, then drove off. Unbelievable I know, but apparently quite common and leads to a reluctance to park anywhere that's not protected from dozy car drivers.)
The situation in Sheffield as I understand it is that there's a 'clampdown' going on; fair enough, but to go straight from a situation where parking was tolerated to one where tickets are issued is a bit excessive and unnecessary. Many of those motorcyclists thought they were OK parking where they did (judging by various forums) because signs aren't always clear, plus the fact that a 'no waiting' restriction applies to the entire highway including pavements isn't always understood.
