I got my 66-year-old sister a mountain bike, and she's quite excited about it. She says, however, that she has some arthritis in her hands, and it hurts to brake when going on a long downhill.

My guess is that this will get better as her hands get stronger.

Anyone else have experience with this?

I wonder whether adjusting the brakes so that they are less tight would help -- that is, her hands would be less open when applying the pressure.