Nope. You very likely wouldn't notice a difference at all. Save your $

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<If you're gonna be dumb, you gotta be tough>
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rather than say you won't notice a difference, I'd say you seem to be the right size for 175. i'm 5'9" with an 83cm inseam and the 175 felt great climbing at low cadence but were hard for me to spin over 95rpm. go borrow a bike with the shorter crank length for a try or buy a cheap used pair if you're undecided

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Irony can be humorous, but it does not have to be.

"I've always said that an Ironman is a reflection of your character" - Kevin Moats

IMO, the best way to est. how different the 172.5 cranks would be compared to 175's would be to plug in your drivetrain specs into sheldon's gain ration calculator.

http://www.sheldonbrown.com/gain.html

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Proud member of Team Tooth Pick (TTP): like a leaf in the wind.

With an 88cm inseam I think there is more reason to switch to 177.5 or 180 cranks than 172.5 for a steady state effort.