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More Notes
Carl Gulbronson recently rode a bike with a NuVinci continuously variable transmission that seemed to work well. It ran quietly and didn't seem to have any noticeable lack of efficiency. It also has a very wide range of equivalent gears and it was easy to make wide shifts at stops or hills. It is available now on several early-adopter brands of bikes (including Breezer city bikes) and sooner or later may be available separately. It is one of the designs that squeezes some hard steel balls or wheels between two round races that can be angled or moved to change the effective ratio (not a hydraulic drive, as has also been mentioned at another recent club meeting).
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The Rotor company in Spain is starting to make "Q Rings" a new variant on the elliptical chainring. Their twist is to have a large number of mounting bolt holes so you can tweak the alignment for different style bikes and different personal preferences. Mark thinks they have about 30 holes (of which four or five would be used at any one time) and could actually be set in 60 different orientations. They are available in 4 bolt 64-104 BCD for mountain bike cranks and 74-130 BCD for road cranks. There are also 110mm BCD Q Rings but it's unclear if these are for is their proprietary 4 bolt circle or the more or less standard 5 bolt ones. If proprietary you would be limited to their cranks (and crank lengths).
SRAM is rumored to be coming out with a 9 speed hub gear with a nice gear range. Carl and Mark will both be keeping an eye out for news on this and will report back to us. Mark is getting to be a big hub gear fan, and although three speeds is generally enough for riding around town, a unit like this would be nice for touring. Now we just have to find out how this hub compares on weight, gear range, efficiency, and price with the current range of 7 to 14 speed hubs from Shimano, SRAM, Sturmey-Archer, and Rohloff. |
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