My daughter's Trek came with a 6-speed Shimano Revoshift SIS Index. It's a new bike. She can shift to higher gears easily but does not have the grip strength to shift back
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Amazon.com : ZUKKA Bike Shifter SL-TX30-6R 6 Speed Right Thumb Gear Shifter Mountain Bicycle Folding Bike Commuter Bike : Sports & Outdoors
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