I have a piranha 140 on a Tomos Streetmate frame. I am experiencing bad vibrations at low rpm in 3rd and 4th gear. It is the worst in 4th gear. It only happens under throttle (load) and causes the whole bike to vibrate and jump around in a bucking fashion. I put it up on a rear wheel stand, ran it through the gears, and experienced the same vibration. I noticed a violent chain bounce that corresponds with the vibration when it was on the stand. I am stumped on what it could be.
Thanks in advance.
Thanks in advance.