Trials transmissions in general are usually not fragile, just the pro. It is a strange design found only in the pro. Mainly the shift to 3-4 and back down 4-3. But in general the whole thing is not a strong design. You need to search the forums and you will see pro tranny problems over and over. The bike works very well, but has always had the most repair issues. Everyone says the newer bikes are better. Just use the brakes more, and not hard shifts on the trail.