I don't think the OP is fighting it about the speeding part which he admits he was doing. What he is challenging is his cuffing, bike impounded and the rude treatment he got. Now of course I wasn't there so I can't say how both sides acted during all of what took place. So I can't judge one way or another and will say this.
When dealing with the law never say you know you were speeding or say how fast you were going (or what ever you were pulled over for) and only give what is needed such as license or ID if you are being detained. The police are not your friends and they will use everything you say against you. Don't be rude and answer with bare facts if you have to. Don't consent to a search EVER...
REMEMBER CYA with the law...