I am planning to assemble a bike for loaded touring in the U.S.A. using a
Rohloff speedhub. I am not sure what is the best solution for the issue of
attaching (transmitting the torque from) the speedhub/rear wheel to the
frame. Dealing with chain tension adjustment is also an integral factor in
this design decision.
What is the best solution?
1.. Standard vertical dropouts on an off-the-shelf frame using the Rohloff
torque arm and a chain tensioner. I am currently using this setup on my
commuter bike.
1.. Pro - Can use an off-the-shelf frame such as a Surly Long Haul
Trucker and save a lot of money, perhaps more than a thousand dollars.
2.. Con - Changing a flat tire with this system is sometimes a bit
finicky. I have had trouble getting the torque arm quick release to release
and reattach without some additional effort. Is the need for a chain
tensioner a negative?
2.. Standard vertical dropouts on an off-the-shelf frame with a rear disc
brake mounting block using the Rohloff speedbone and a chain tensioner?
1.. Pro - No finicky torque arm.
2.. Con - Will pannier/rack mounting be a problem? Does not eliminate
the need for a chain tensioner.
3.. Custom frame with Rohloff sliding dropouts?
1.. Pro - Mechanically simple, elegant, with fewer moving parts to
break. Frame could easily be used with a derailleur system in the future by
simply changing the bolt-on right rear dropout.
2.. Con - Really expensive. AFAIK, only available by getting a custom
frame built. The Rohloff dropouts are also expensive. I will be spending
around $500.00 US extra for a speedhub over a derailleur system. Why not
spend an extra thousand or two for a custom frame? Will changing a flat tire
and maintaining proper chain tension be simple and easy? Is varying chain
tension during the pedal cycle caused by a slightly eccentric chainring
likely to be much of a problem? Sheldon Brown talks about this problem in
tandems on his site.
4.. Non-sliding vertical dropouts designed to handle the additional
torque combined with an eccentric bottom bracket like Thorn Cycle's frames.
1.. Pro - Uses a less expensive (than custom) off-the-shelf frame from
Thorn.
2.. Con - Frame not easily modified to use a derailleur system without
welding on new dropouts and repainting. Some people have described problems
with the eccentric bottom brackets such as the setscrews denting the bottom
bracket.
5.. Same as D. with a chain tensioner and no eccentric bottom bracket.
1.. Pro - No eccentric bottom bracket?
2.. Con - I haven't seen this available as an off-the-shelf frame.
Obviously this could be custom built. Probably wouldn't have much advantage
over option B. described above.
6.. Horizontal dropouts with axle bolts and nuts rather than a quick
release skewer.
1.. Pro - Simple solution for chain tension adjustment?
2.. Con - I haven't seen a modern touring frame with horizontal
dropouts. Wrench needed to change a flat tire.
7.. Some other permutation of these options: vertical dropouts,
horizontal dropouts, Rohloff OEM sliding dropouts, custom dropouts, torque
arm, speedbone, chain tensioner, and eccentric bottom bracket?
Thanks in advance. This is not a question about whether or not to use a
internal gear hub on a loaded touring bike.
BobT