Bicycling/Fixing Gearbox in Mountain Bikes.
Is it possible to fix Gearbox in Mountain Bikes?.
If yes, What Speeds can be achieved by the cyclist?.
What do you exactly mean with to fix a gearbox in mountainbikes?
The nowadays moutainbikes are having 30 gears (3x10)", powered by a drivetrain with chain and sprockets and a deraileur. Some are having a special kind "gearbox" without an derailleur. This is placed into the rearhub. Very expensive but flawless, no dirt can enter the gears, unlike to the chain and derailleurs.
The what speed can be achieved, this depends on the skills/condition from the driver. Downhill they can reach speed from above 100 kilometer/hour.