the Sinnis is put together well but performance wise its on the lower end of 125's I used to ride with a guy with one when I had a Rieju Marathon Pro 125 SM could be in 4th and he'll just about keep up but for London it could be okay, the tyres are always skittish since they're nylon last ages but no real feel of grip I would suggest Michelin Pilot sportys very good tyres had them fitted to my Supermoto.

Kennon