Radius Brakes : r/BikeMechanics

My shop has been seeing a few new bikes coming with Radius brakes that have a "pumping up" feel. First pull of the lever brings it to the bar, and the next feel fine. But let it sit for 5/10 seconds and it drops back to the lever.

Replacing barb and olives doesn't seem to do anything.

However, you can use a syringe on the lever end and pressurize the system while pumping the lever which is getting it to feel like a normal brake and have more power available on the first pull.

The main brand we've been seeing it on is Trek, and when we called into Tech Support, we got the feeling they've received calls about the issue and didn't have a fix for them to try.

Hopefully this helps someone else out!