I would not know I have one of the two I got on a hi-end electric bike and have not gone more than 32mph. But it seems well sturdy enough that it would handle 70mph considering how much shaking and friction it gets to the handlebar. Certainly the main clamp is sturdy enough and when you lock the clasps in place for the the top and bottom grips it aint goin no where. The other one I use as a desk stand.