Going past everyone who's already stopped at some lights to get to the front and then setting off at glacial pace forcing most people (who've already overtaken them at least once already) to overtake them yet again.
Bonus points for going past the point where they can see the traffic lights so there's a further delay as they can't tell they've turned green.
[EDIT] It's only really a problem for 3 or 4 months in the summer whilst the fair weather cyclists are about. In the remaining part of the year the shoalers are too few in number to cause any real concern.
Going past everyone who's already stopped at some lights to get to the front and then setting off at glacial pace forcing most people (who've already overtaken them at least once already) to overtake them yet again.
Bonus points for going past the point where they can see the traffic lights so there's a further delay as they can't tell they've turned green.
[EDIT] It's only really a problem for 3 or 4 months in the summer whilst the fair weather cyclists are about. In the remaining part of the year the shoalers are too few in number to cause any real concern.