at the end of the day adidas is a trademark term, so there is always a risk you could loose it. if you are going to invest a lot of energy into the site then remember it could all be for nothing if you have to hand over the domain. i personally would not risk having a domain name using a trademark term.
Though I'm a US attorney, not a UK one, I'm going to say yes, you're asking for trouble. Addidas is a very famous brand worldwide with a strong trademark. I'd guess they have the time, money and inclination to defend it. I'd recommend you drop the URL. Deena _________________________________________________________________________________ Any opinions are offered without knowledge of the specific law of your jurisdiction and with only the limited information provided in your post. No advice given here should be reasonably relied upon by you or any third party without consulting an attorney who is aware of all of the facts and law surrounding your situation. Any advice given here is not intended to create an attorney-client relationship in any way.
Im from the UK too mate and to be honest, I wouldnt go for it purely because your gonna end up using a trademarked brand in your URL and that domain is preety sweet so if they ever come to register it for lets say a famous charity marathon, then "Addidas Superstars" would already be taken! Would do you think they would do? regards