Either one will work just fine. The difference is that the DuoTrap is much cleaner looking and you don't have to worry about accidentally knocking it off with your foot. The advantage of the Wahoo unit is that it can used on multiple bikes; providing you use the o-rings rather than the zip ties to secure it to the chain stay.
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HCFR Cycling Team
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2017 Colnago C-RS
2012 Colnago Ace
2010 Giant Cypress