What model # r these older Dura-Ace arms?
08-29-16, 10:40 AM
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What model # r these older Dura-Ace arms?
Hello. New member here. I current have a JIS bb that is 103mm length and I'm trying to find out if these older DA arms would have a decent chainline (43 ish)?
I plan on using these arms on my fixed gear. I noticed from Sheldon Brown's site that the DA 7410 is perfect with a 103mm bb, but the other series need 107-110 range. Any help appreciated!
I plan on using these arms on my fixed gear. I noticed from Sheldon Brown's site that the DA 7410 is perfect with a 103mm bb, but the other series need 107-110 range. Any help appreciated!
08-29-16, 11:40 AM
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Looking at VeloBase, I'd agree - 7410. 7700 looks similar but Octalink.
VeloBase.com - Component: Shimano FC-7410, Dura Ace 7410
VeloBase.com - Component: Shimano FC-7410, Dura Ace 7410
08-29-16, 12:09 PM
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They are a low profile crank that does indeed use a 103mm bottom bracket but the chainline is no different than any other Dura Ace double crank even though they require longer bottom bracket spindles. The shorter bottom bracket and design of the cranks allows better ankle clearance for people who pedal toes out. The last generations of Campagnolo high end square taper cranks were similar, using a 102mm bottom bracket spindle, but the chainline is identical to the Ultra torque cranks that replaced them
Last edited by alcjphil; 08-29-16 at 12:26 PM.
08-29-16, 01:00 PM
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Hello. New member here. I current have a JIS bb that is 103mm length and I'm trying to find out if these older DA arms would have a decent chainline (43 ish)?
I plan on using these arms on my fixed gear. I noticed from Sheldon Brown's site that the DA 7410 is perfect with a 103mm bb, but the other series need 107-110 range. Any help appreciated!
I plan on using these arms on my fixed gear. I noticed from Sheldon Brown's site that the DA 7410 is perfect with a 103mm bb, but the other series need 107-110 range. Any help appreciated!
The fact that it used a 103mm BB might not be as awesome as you think. Remember that the chainline is measured to a point between the two chainrings, so the outer ring is a little further out and the inner ring is a little further in than that 43.5mm figure. My usual approach is to get a double crank that originally used a longer BB so that when I use a shorter BB, the outer ring position moves inward toward that 42mm ideal. (For example, I'm using a Sugino GLP that originally called for a 116mm BB, but with a 103mm BB for perfect chainline.) But with the DA 7410 crank, you're stuck because you can't get a shorter one!
