Dan;
The hex key is for loosening/removing the chain tensioner which is part of the VDO kit for bikes with vertical dropouts. The bolt which mounts it to the derailleur hanger has a socket head which uses a hex wrench. What is the 11mm wrench that you mention used for?
The new NuVinci N360 would be more compatible with your Surly as it uses a standard SS/FG/IGH 15mm wrench size nut on both sides.
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Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
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