Q factor query

uad782
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Q factor query

Postby uad782 » Tue Nov 06, 2018 7:47 am

Hi everyone,

When riding my Lynsey GR260 I very sporadically strike my heel on the left chainstay. The bike came with crappy FSA Gossamer cranks and a BB386EVO bottom bracket. I have replaced them with an ultegra crankset and bb.

So has this change brought my heel closer to the chainstay? Is the Q factor the only thing I have changed or do bb widths have some involvement. The Q factor for ultegra is 146mm while the gossamer is 145mm I think. I found the fsa Q factor on wiggle as their website is hopeless.

The heel strike is not a drama but am curious if the change in crankset has made it worse.

Thanks

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biker jk
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Re: Q factor query

Postby biker jk » Tue Nov 06, 2018 9:55 am

Curious to know the gap between the left hand crank and chainstay. On my Lynskey it is only 5mm but I don't have heel strike. Do you have your cleats at an angle such that your heel is inboard?

macca33
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Re: Q factor query

Postby macca33 » Tue Nov 06, 2018 10:37 am

In your case, the BB width has stayed the same at 86mm, you've only changed the cranksets. If you state the Ultegra has 146mm Q-Factor, vs the FSA at 145mm, then you've increased your Q-Factor very slightly, not reduced it.

I would also check your cleat alignment.

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uad782
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Location: Somewhere near Malabugilmah

Re: Q factor query

Postby uad782 » Thu Nov 08, 2018 7:38 am

Thanks everyone.

I have 8mm from crank to chain stay. Chain stay widens significantly near heel though. I will check cleat alignment as it appears I turn my heel in sometimes. Maybe something to do with hip rotation etc too.

I am confused about the 86mm though as bike only has a 68mm BB. I am curious is BB is longer such as 86mm do you need a different set of cranks as their axle could be too short??

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Duck!
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Re: Q factor query

Postby Duck! » Thu Nov 08, 2018 8:28 pm

uad782 wrote:I am confused about the 86mm though as bike only has a 68mm BB. I am curious is BB is longer such as 86mm do you need a different set of cranks as their axle could be too short??

It's either a BB30 frame with adaptors/spacers, or English threaded with outboard bearings; either way the assembled width works out the same.
I had a thought, but it got run over as it crossed my mind.

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