Hi , we use motorola T5522s when touring with autocom, its important to ensure that the radios are set up for right volume AND separetly sensitivity level set for NOISY environment to avoid "normal" background road noise trigering transmit, we had some fun until we worked out why we had so much awful noise when neither of us were talking
a quick read of the manualaugie) for the radios and it was sorted!
range is Ok for normal use and they take up little space in tank bag side pocket (keeps aerials vertical as this apparently provides slightly better range)
If you are meaning running the VOX on the Motorola's by themselves then no, they are too sensinstive for bike use. The VOX is for mainly walking or running not good on a bike.