Sigma claims that the brake light fits u-brakes, v-brakes, canti’s, road calipers, mechanical disk brakes…but it won’t fit hydraulics. We did have some trouble installing the Sigma brake light to both bikes that have Shimano 105 11 speed brakes installed. The clearance wasn’t enough to install the brake. In order to install it on our 11 speed Shimano brake we would have needed to compress the light a bit too much between the cable stop and anchor bolt, so much so that the light would have turned on without pressing the brake lever. We’re not sure if this installation issue is true for every Shimano 11 speed brakeset but it was true for both our attempts. Our wheels were not considered wide and the opening of the brake was very average for a 19mm wide rim with a 23c tire. In the end make sure you check with your local bike shop about their return policy in the event the light won’t fit your rig. In the image below you can see we didn’t have enough cable exposed on our 11 speed 105 rear brake to install the light. A bit of a disappointment.