Problem with rear brakes

Bicycling
1

2010 Kona Dawg with shimano hydraulic brakes. I bought the bike new in 2012 and have done nothing with the brakes.

The last couple of rides the rear brakes have not felt “right”. I have to pull further, I don’t get the same feel and she does not stop as fast. I pulled the pads and they were not dirty and there was plenty of pad left. A buddy said I should bleed the brakes. Any other thoughts?

I have bled car brakes before . . . is there a difference? The calliper does have a bleed screw.
It also says to use mineral oil . . . huh?

Any thoughts, guidance and well wishes would be appreciated.

2

I’d first clean the pads and rotors with alcohol just to be sure, but it sounds like a bleed in in order…It’s a fairly simple process if you have the right tools. Shimano uses a proprietary mineral oil so you’ll need to get some. Do not put DOT fluid in a system designed for mineral oil!

Some good instructions on bleeding 2012+ Shimano brakes can be found here:
http://www.epicbleedsolutions.com/blog/how-to-bleed-new-shimano-brakes/

There’s a bunch of youtube videos out there too.

3

I did clean the brakes with alcohol . . . but not the rotors. Gotta try that and get me some oil. Tks

4

If lever feel is spongy, then it probably is a bleed.

I’ve used baby oil in a jam in shimano brakes. It’s been argued to death on the interwebz whether or not you can do that, but I’ve lived to tell about it.
I like to tap the lines, lever body and caliper while bleeding to encourage air bubbles to escape.