Cateye does offer a rack mount for the 1100 that fits the Tubus rack or other European racks with 50mm C to C taillight mounting holes. For sale on their web site. It seems secure to me. I have seen someone lose the end cap battery cover from the 1100 taillight though.
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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
Visit and join the Yahoo Geared Hub Bikes group for support and links.
http://groups.yahoo.com/group/Geared_hub_bikes/