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I have a set of 170mm Affect R cranks. I don't see how they can be correct.
Firstly the crank length is measured from the centre of the BB to the centre of the pedal spindle so the ruler isn't lined up with the pedal hole by about 10+mm. If it lined up properly I could be convinced that they were a 175mm crank possibly but I do agree that is seems longer than the 170 you say it is. Get a longer ruler. On second look I think you'll be surprised when you line it all up properly. I'd buy 170mm.
 

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Disgruntled Peccary
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1) I'm aware of how cranks are measured.
2) It's a 170, unless the box lied.
3) The rulers there just for scale.
4) If the arm was the same, the hole would be way too close to the arm end.

I can go measure with calipers if you'd like, but you're gonna have to trust me (and RaceFace) that this is a 170 arm. So, I don't see how the CS guy can be correct that a 175 arm and 170 arm are the same length.
 

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1)

I can go measure with calipers if you'd like, but you're gonna have to trust me (and RaceFace) that this is a 170 arm. So, I don't see how the CS guy can be correct that a 175 arm and 170 arm are the same length.
I agree the CS guy can't be right. I think I said that in my post earlier. From your last post it wasn't obvious (well to me at least) that's what you were saying. I'm 100% with you.
 

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Disgruntled Peccary
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I agree the CS guy can't be right. I think I said that in my post earlier. From your last post it wasn't obvious (well to me at least) that's what you were saying. I'm 100% with you.
Yea, sorry.. I'd meant to quote the post, then since I was in the shop.. got distracted taking the pic
 

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I'd be personally very surprised if a 170 and a 175 arm were the same length with the pedal insert just moved slightly for the shorter version. But I've never lined up two of the same models of any kind to actually compare this. Just assumed they were of different length. I have a Shimano M9000 and SLX M7100 in 175 and 170. There is a overall length difference there, but they are different generations and series.

I could see on a lower end crank that this could be possible as a way to keep costs lower.

Looking at the RF Aeffect, There wouldn't be much material left, if you simply moved the pedal insert 5mm further. Would be interesting if someone had a 175mm in RF and could post a picture in the same orientation as @dysfunction did.
 

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Depends on the model. I know Sram NX cranks use the same body for 170 and 175mm. I believe Sram's carbon cranks use different length bodies for 170 and 175
If this were true, I think anyone who goes with a shorter crank should know or compare if they're replacing with the same version. To me, the majority of rock strikes are on the end of the crank arm, not the pedal. A person might think they are going with a shorter arm for that reason only to find out they've not accomplished their goal.

That said, I do think we tend to all run crank arms slightly longer than optimal out of tradition.

New standard anyone? :)
 
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