I know the chances of getting caught with a dongle are extremely small, but I wouldn't take the risk of using one. If your involved in a serious accident (doesn't have to be your fault) and the police find your bike has been modified then you could be in very serious trouble. The reward (being able to go really fast) is not worth the risk (big fine, bike confiscated maybe even prison sentence).stick a dongle on one and you will **** all over them for 20 miles anyway you should see the look on the face when a 20kg fs mtb blasts past them on the road