Re: speedhub 100Nm limit
The Rohloff hub is a nice piece of work but you can buy 3 Nuvinci hubs for the same price as one speedhub. I also have a 20" rear wheel and searched around and got a complete sachs 3x7 hub/front wheel takeoff from a new bike on fleabay for $250. Talk about some gear range! The Shimano Nexus 8 is supposed to be reliable also. There are plenty of options out there, but the trick to internal hubs is in how you shift them. If you shift under too much load they will implode, just back off the gas a bit while shifting and you will be fine, even with an old 3 speed model.