During my ride yesterday, my rear derailleur started to act up. It was skipping gears at random. I took it into the shop and while the mechanic was working on it, I asked him if he could also check my computer since that was acting up. A few weeks ago, the mileage was going backwards and then I noticed that during my commute, the distance wasn't accurate. He checked it out and fixed it. I checked it after my ride today and saw that my maximum speed was 57.3 mph!!! So do I take it back to the shop to get it fixed again or do I keep it the way it is and try to see if I can break 100 mph?