Measuring yourself properly will help you find the rain riding gear that will provide you with the best fit. To make sure that the motorcycle gear you get will not only keep you dry but also comfortable, you should measure yourself only after you’ve put on the gear you will use under the rain suit.
Once you’ve done so, measure yourself as you normally would. Use a measuring tape and measure your chest and waist. Define what comfortable means in your case and choose accordingly. While some bikers prefer the rain gear to be a bit loose, others might want a tighter fit. Some one-piece suits or pants might be adjustable to meet different preferences.