I have both the Pletscher and VO center stands as well as a Hebie one on different bikes. The VO is a bit wider while lowered while the Pletscher is smoother in operation. Both have the problem of still allowing the bike to tip during loading if too much weight is placed on one side. A standard bicycle is just so light weight that too much off center weight can overbalance all center stands I have tried except the Xtracycle specific one I have on my Surly Big Dummy.
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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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http://groups.yahoo.com/group/Geared_hub_bikes/