I wanted to replace my front wheel disc brake pads (Shimano BR-M785).
For the purpose, I removed the front wheel and removed the existing pads. Then I tried to place the new pads and found out the would not fit properly.
After asking, I was advised to "push the pistons back to the callipers", This is, to use a non-metal device to push back to their place the two circular pressers (pistons?) that where outstanding preventing me from inserting the new pads.
Sure enough, after doing this I could install the new pads. Placed back the wheel and now when I brake there isn't enough pressure to cause any effect. The brake pedal is totally loose, as if there was nothing to brake with. Looking carefully, it seems that the pads are moving slightly and touch the brake disc, but nothing enough to make it brake.
Any advice? No liquid has leaked, nothing seems broken.
I'm sorry I don't know much about any of this, I though I could save some money doing it myself... seemed easy enough.