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Discussion Starter · #1 ·
I have a Czar, size large, and the 2013 S-Works 175mm crank being used is rubbing the right chainstay under extreme hard pedaling. At first I thought it was the rubber boot crankarm protector, but even after cutting away the boot's inside I'm still having the inside of the crank arm touch the right/DS chainstay.

The crank and bb are properly installed. The S Works crank is a 166 or 167 factor, and there is proper distance between the chainstay and crank arm in all situations except the aforementioned in-saddle and out of saddle situations with extreme torque. I'm 162 pounds and a XC racer so it's not like I'm an insanely powerful torque monster.

I'm aware the S Works crank on a Czar combo is pretty rare. At this point I'd rather not use a Shimano crank with my Praxis conversion due to this particular Czar being spec'd as a lightweight marathon racer.

XX1 owners having no issues?
Race Face Next SL owners having no issue?

Thanks in advance.
 

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Hey;

I am planning the same setup, sorry to hear its not working. What BB are you running. If its the Sram style, is it possible that your getting a little flex there?

Have you entertained putting wave washer to the other side?

My cranks are off a 2012 S-Works Stumpy FSR, I just guessed that they would be wide enough?
 

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Discussion Starter · #3 ·
Using the oem/factory Specialized 30mm BB.

Hey;

I am planning the same setup, sorry to hear its not working. What BB are you running. If its the Sram style, is it possible that your getting a little flex there?

Have you entertained putting wave washer to the other side?

My cranks are off a 2012 S-Works Stumpy FSR, I just guessed that they would be wide enough?
 

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Discussion Starter · #6 ·
Just read this possible fix in the Speci section on my xpost. Hope it helps you or someone else. Thanks for taking the time to reply, renoirbud.

You should be able to reposition the spacers on the spindle to push the RHS out a little relative to the LHS, and that should fix it.

As you're probably aware the crank will always tend to "torque in" to the RHS, (not the LHS) due to the position of chain on the RHS. This torque "moment" (to use a term from physics) will be accentuated when using low gears, as the torque you are applying is greater. In these situations this torque "moment" will cause your rear triangle to flex outwards (to the RHS) dragged by the chain. So, in other words, your crank "strike" is caused, not by a flexi crank, or frame, but by the rear triangle.

So, technically, you frame isn't flexing, it is your rear triangle (including the bearings & pivots) flexing.

On an "ultra-torque"-style crank (as the SW crank is), you have relative freedom to place the spacers where you need them to ensure appropriate chain stay clearance. Your LBS should have pointed this out to you.

FWIW, I have an SW crank on a SW Epic and have around 4-5mm clearance on the RHS and no strike, although, out of the box, I had to re-adjust the BB & spacers to stop strike.
 

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I run a 2013 S Works crank, 175mm, on a large Czar. Am also fighting the issue of DS inner arm rubbing chainstay on extreme torque, too. The stock/oem washers and spacers will not combine - in any way, shape or form - to remedy the problem.

Then I swapped the left side to the right, and vice versa, and slipped on a thin washer (picked up from Ace Hardware). Thin enough to allow the Hirth joint to completely bolt together and give the DS arm enough clearance under extreme pedaling to not rub the stay. There's hardly any room on the left side and visibly more on the right, and under hard pedaling the left crank moves away from the chainstay and the drive side moves toward the flexing chainstay but does not touch.

I think it's just a mm or two difference in Q Factor from the likes of 168 XX1 and other wide cranks vs the S Works. It's not crank flex. The S Works is extremely stiff. It's a combination of the direct mount ring and chain and S Works crank bb pull the chainstay into the crank arm.
 

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Supersonic Garfield
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I have a Czar, size large, and the 2013 S-Works 175mm crank being used is rubbing the right chainstay under extreme hard pedaling. At first I thought it was the rubber boot crankarm protector, but even after cutting away the boot's inside I'm still having the inside of the crank arm touch the right/DS chainstay.

The crank and bb are properly installed. The S Works crank is a 166 or 167 factor, and there is proper distance between the chainstay and crank arm in all situations except the aforementioned in-saddle and out of saddle situations with extreme torque. I'm 162 pounds and a XC racer so it's not like I'm an insanely powerful torque monster.

I'm aware the S Works crank on a Czar combo is pretty rare. At this point I'd rather not use a Shimano crank with my Praxis conversion due to this particular Czar being spec'd as a lightweight marathon racer.

XX1 owners having no issues?
Race Face Next SL owners having no issue?

Thanks in advance.
I had the same issue with my s-works crankset. My first ride was a muddy 3 hour ride. I can assure you all clear coat was gone, and I did not notice it until after the ride. Clearance seemed fine, like yours.

I ended up selling my s-works and got Next SLs. Issue gone.

T
 

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Discussion Starter · #9 ·
I did the mod mentioned by danK and it fixed the rubbing under hard torque. I didn't want to sell the S Works and fork over more $$$ for another highend light crank, and fortunately the thin spacer worked....in addition to putting the L crankarm on the Right and vice versa.

But it's good to know the Q Factor is an issue with some cranks and obviously not with others.
I had the same issue with my s-works crankset. My first ride was a muddy 3 hour ride. I can assure you all clear coat was gone, and I did not notice it until after the ride. Clearance seemed fine, like yours.

I ended up selling my s-works and got Next SLs. Issue gone.

T
 
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