Rear brake feels weak

[Flyingpony]

Had new chain and sprockets fitted the other week and since then I've noticed that the rear brake feels weak. It's no longer as firm to depress and performs worse than it used to

The brake clipper assembly was temporarily unbolted from the frame during the work, but no hoses were undone or fluid bleed.

Before you ask 'What's the back brake', I use it to kill the last few km/hr when stopping because it's smoother to control at such low speeds than the front.

What do I have to do to get it fully functioning again?
Thank you.

[bugjuice]

tried brussle sprouts? My mummy told me that they would make me strong..

else check the fluid level, and make sure it hasn't got any air in there, which means you might want to bleed the caliper to check..

[That Guy]

Sounds like when they moved the caliper a bubble of air got from the resevoir into the brake line. Like bjuice said bleed it.

[Motu]

The rear caliper sometimes has to be repostioned when the rear wheel is moved,some do it automaticly.Slacken the caliper mounts and maybe the axle nut,pump the pedal a few times and retighten everything...then see how it is.

[DingDong]

If you use the rear break??? alot, your disk may have wear, and wasnt positioned back in the grooves it's made, heating the piston and then the fluid and dampening the power.

reposition it, and see how it goes.

Not that I've seen your, bike but that would be my first point of contact