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Q-factor for Ultegra cranks?(4 posts)

Q-factor for Ultegra cranks?BergMann
May 26, 2003 8:59 AM
Does anyone know what the q-factor for an Ultegra 9-sp double on a 109.5 BB is? Couldn't find it on the Shimano website.

I want to swap out an older set of D-Ace cranks on a 113 spindle, and am concerned about crank clearance.
re: Q-factor for Ultegra cranks?gtx
May 26, 2003 1:11 PM
Don't know the numbers, but I'm guessing those older DA cranks have a lower q factor, though, than the 9 sp Ultegra. I know the older 7-8sp DA cranks are almost 1 cm less than the older 7-8sp speed Ultegra cranks. I think Shimano makes Ultegra cranks with a wider q to work with a greater range of bikes. I wouldn't worry about clearance if you're going to the new Ultegras. I might worry about your knees, though, if you're used to less q.
Anyone willing to measure their Ultegra setup?BergMann
May 26, 2003 8:13 PM
It's relatively easy, particularly if you have vernier calipers.

1) Rotate your right crankarm upwards, parallel to the seat tube. Measure from the outside (i.e. left) of the seat tube to the outside (i.e. right) of the crank where it contacts the pedal axle.
2) Repeat measurement for the left crankarm (this time starting from right side of seat tube)
3) now measure seat tube diameter and subtract this figure from the sum of measurements 1 & 2.

Q-factor on my old DA cranks is 140mm. Q factor on my mountain bikes is upwards of 160mm, and my knees like them a lot better than my road setup, so if the new Ultegra is wider that would actually be a plus.

Any takers?
Q-factor for Dura Ace & Ultegra according to Shimano USABergMann
May 27, 2003 9:01 AM
For the record, I just got off the phone with Shimano USA, and their measurement for the Q-factor on both Dura-Ace and Ultegra cranks on a 109.5 mm spindle measured inside-of-crankarm to inside-of-crankarm is 115mm.

To get an "actual" measurement of the minimum distance between your feet, you need to add the width of the each crankarm to that number.

For my purposes, the 115mm "inner" Q-factor is only 1 mm more than my measurement for my old Dura-Ace cranks on a 113mm square-taper spindle, so I'm no longer worried about frame clearance.