This guide shows you the basic idea of why not to squeeze your brake lever while your wheel is off. This fix works on most hydraulic disc brakes, but some need to be decompressed evenly on both sides to ensure good performance. Now that you know the basics, find some information on your specific brakes.
If you bought a mountain bike with hydraulic disc brakes, chances are the shop technician gave you a stern warning: Don’t pull the brake lever with the wheel off. You’ll be sorry. They might have even given you these wedges to put in place to prevent it.
Normally the pads push against the disc when you squeeze the lever. If you do this with the wheel off, the pistons push in too far, and basically contact your disc brake 100% of the time. It’s not fun to ride like this.
Luckily it’s easy to fix. You just need to push the pistons back out, no special tools required. First remove your brake pads, which is usually a matter of pulling out, or unscrewing a pin at the base. They then pull out from the other side.
Once you’ve removed the brake pads, just push the pistons back out firmly with a tool. Really, almost any tool is okay for this purpose. There’s one on each side. They won’t move much, but you will notice it. Reinstall your pads, and you’re done! No big deal.
Your wheel should spin free and clear now. I hope this helps someone out. Thanks for riding with me today, and I’ll see you next time.