I had a Zena disk lock. First, it would not fit on the front disk of my 2000 Bandit. It would fit, with great difficulty on the back disk. Upon trying to lock it, the alarm would sound sometimes, then it would start beeping for no reason 'till the batteries were dead (the beeping was an indicator of low battery, I am told. If so, the battery life is absurdly short). All in all, a poor product IMO, although if you are successful in getting it on the bike, it would probably prevent a roll away theft in that it seemed strong enough.