You can ONLY ride a 125 until you have passed your mod1 and mod2. Upon completion of your mod2 you are allowed to ride any bike you want up to 33bhp or if the bike is more than 33bhp as standard then you have to fit a restrictor kit limiting the bike to 33bhp. There are some 250's (Ninja 250, CBR 250) that are below the 33BHP rule and also some 400's. One of the best bikes for restricting is a SV 650 as it takes the restriction very well and restrictors for them are readily available on eBay. For me Mod 1 was easier than Mod 2 as I got nervous on my Mod 2. Hope this clears some things up.