The Hotshot Pro 150 mount won't work if your seat post or seat stays aren't round. If that's the case you need an accessory that's sold by Cygolite called a flexible seat post mount. Here's a link from Cygolite

https://shop.cygolite.com/product.sc...&categoryId=91

If you get the Hotshot Pro 200 it already comes with the flexible seat post mount so that's something you wouldn't need with this model. Link from Cygolite to Hotshot Pro 200

https://cygolite.com/product/hotshot-pro-200-usb/