M2S R750 rear brakes not working after changing tire?

[johnw]

Looking for some help. I have a M2S R750 and when my son was changing the rear tire that had a flat somehow the rear brakes got messed up. When I squeeze the brake lever for the rear it has to now be pulled all the way to the handlebar and will barely engage the rear brake. I never adjusted brakes , does anyone have any info on doing it?

Also I seen someone posted about Kevlar tires so I don’t get any flats , where can I get some?

 

[cityscape]

That is strange... did the brake lever get pulled while the wheel was off? These are hydraulic brakes, it sounds like they have air in the line but I don't think the caliper can close enough to do that. Unless you loosened the caliper screws.

The only time you need to bleed brakes is when you aerate the lines.... it is a mystery how you got air in the lines unless you actually loosened the line removing the wheel. I have bled tons of brakes in my time but not these, it's way to much to explain in writing here, I would have to read up on these and find out which screws are the bleeders.

Sounds like air in the brake lines if they are hydraulic. YouTube will show you how to bleed the brakes.

 

[ebikejames]

Yeah it’s just air in the lines. This happens when the breaks get pulled with no rotor between the calipers. The pads go in too far and it bleeds some fluid and gets air bubbles in it. There are videos on YouTube about how to add fluid and get it working but you can also have it done at any bike shop.