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Discussion Starter · #1 ·
I have one season on my 172.5 Dura Ace FC7800 Double cranks, but due to knee issues and short legs I really need to drop down to 170 cranks. Does anybody have DA 170's they would like to trade me for? They are in great condition, minimal rub on the driveside crank arm.

By the way I would have put this in the classifieds, but I don't want to sell them and there isn't a 'trade' section. If I need to move this to a different section, please let me know.

Jason
 

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Carbon Fiber = Explode!
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I have a sakae square taper 20 dollar JIS I can trade...
 

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Skepticynisism
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First of all, let me just say that I'm almost completely ignorant of all of these little details. But, is there really a noticable difference between 170mm and 172.5mm? I mean that is almost literally nothing. Can anyone really notice such a subtle change in crank arm length? I know I couldn't.

Do you think this will really help you?
 

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road bike resurrector
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When I went from 170 to 175 I felt a pretty big difference.
 

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Discussion Starter · #7 ·
I would like to try to trade for something comparable, either Dura Ace or maybe try some SRAM cranks. I would be willing to throw a few bucks in for Reds.

About the 172.5 to 170, well I was riding last year and by the end of the season my left knee was shot and my right wasn't all that good either. I was given the option of surgery, but also given an option to a professional fit. I went to the fit and you can see in the videos that my stroke goes a little high and a little on the low side. With shimming my one shoe, changing my pedals, saddle, shoes, and stem; my ride is a complete 180 degrees now. My next thing to do is change my cranks. The little changes like a shim in the shoe made a huge difference, it seemed very minute to me on the bike, but when watching the video it was big. My knees were more in an up and down line rather than swaying out and the bike was noticably more stable. I am looking into getting orthotics because I have fairly flat feet.

If I had gone the surgery route and not bothered with a professional fit, I would have been in the same boat again with a bum knee by the end of the season. I have been riding a long time, but my habits and feet have really caused me issues. With my flat feet my ankles rotate in a little, causing my knees to go at a funny angle, all the way up to my hips. Well, this was causing issues on the bike too. This inevitably caused my quads to get bigger/stronger and the inside muscles to get weak, also my IT band is extremely tight.

I have some issues to work on, but thankfully I chose to go to the fit. I will see in the future if it helps.
 

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I have two bike with 172.5 Dura Ace 7800 and one bike with 170 FSA. You can feel the difference.

Seems like a pretty fair trade:
 

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There's a difference. Every little millimeter helps when it comes to smoothing out your pedal stroke and taking the stress off your knees.

DA also makes 165mm cranks as well. I believe Excel sports had them in stock, the 7800 for $320. And you can usually find 170 on Ebay for around $170 or less.

When it comes to knee pain I wouldn't worry about money too much.
 

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Impulse Athletic Coaching
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Buzzard said:
First of all, let me just say that I'm almost completely ignorant of all of these little details. But, is there really a noticable difference between 170mm and 172.5mm? I mean that is almost literally nothing. Can anyone really notice such a subtle change in crank arm length? I know I couldn't.

Do you think this will really help you?
Yes. Especially on those 5-6hr rides.
 
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