BB86 help

Discuss light weight issues concerning road bikes & parts.
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btompkins0112
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by btompkins0112

I was was thinking of getting a replacement crank for my bb86 frame. Right now it has the Shimano bb, and an Ultegra crank. Would an FSA Mega-exo crank be a straight swap? Don't want to mess with the bb at this time so just looking for a plug-and-play swap.

by Weenie


Mr.Gib
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by Mr.Gib

I think you need a different BB for FSA cranks - others with more knowledge will confirm.

What I would suggest is you get the crank you really want and then deal with the BB. They are really simple to change and most are very affordable. If you are not up to it, any shop should be able to handle it. My tip is to set the new BB with a bearing retention compound like Loctite 641.

FWIW the SRAM BB has been the easiest spinning of the BB's I have tried. New SRAM Red crank is light too and available for just over $300 in places.
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btompkins0112
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by btompkins0112

Thanks! That's what I had suspected, but I knew that the spindle diameter and length was pretty close from Shimano to Mega-exo.

:cheers:

FIJIGabe
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by FIJIGabe

BB86 is a press-fit bearing, and FSA uses their own dimensions. Shimano and GXP bearings will not work, AFAIK. The BB86 standard uses no external cups or need to spin it on. If you have the appropriate tools (Park Tool offers a BB90 tool - works on BB86/90/92), remove the old Shimano bearings, clean and lubricate as appropriate and press in the new bearings (preferably using a press-fitting tool, but a careful soft mallet strike does the trick). Finally, lubricate and install your crank. Total removal/install time should be no more than 20 minutes.
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ms6073
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by ms6073

Mr.Gib wrote:I think you need a different BB for FSA cranks - others with more knowledge will confirm.
FSA's alloy road cranks will work with the Shimano bearings while FSA K-Force and SLK Carbon cranks have an ~1mm larger diameter spindle and will require FSA's BB86 bottom bracket.
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gn1tmac
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by gn1tmac

the shimano bb86 press fit that came with the scott addict and my plasma 3 worked with my 7900 dura ace cranks (obviously!) and with my FSA K-Force Light SRM crankset.

The FSA pressfit bb86 does not work with the FSA K-Force Light, there ends up being a space of about 1-2mm when you try and tighten down the crank bolt. This is because the shimano bb sits 1.5mm outside the frame on both sides while the FSA ceramic pressfit with aluminum lip sits 1mm. I don't see how you could space anything other than the putting spacers in front of the bearing which can't be the answer as it already throws off your chainline if you space it on the none drive side and spacing the drive side just seems wrong

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btompkins0112
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by btompkins0112

Wow....so the K-Force cranks will work? May have to get some to try it out.

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ms6073
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by ms6073

gn1tmac wrote:the shimano bb86 press fit that came with the scott addict and my plasma 3 worked ... with my FSA K-Force Light SRM crankset.
The FSA pressfit bb86 does not work with the FSA K-Force Light, there ends up being a space of about 1-2mm when you try and tighten down the crank bolt.
That is surprising as we have 2 FSA K-Force Light compact and 1 standard SRM and none of them work with anything but the FSA BB86 and I have tried Shimano, Enduro, and Rotor.
Michael - The Anaerobic Threshold is neither...

gn1tmac
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by gn1tmac

ms6073 wrote:
gn1tmac wrote:the shimano bb86 press fit that came with the scott addict and my plasma 3 worked ... with my FSA K-Force Light SRM crankset.
The FSA pressfit bb86 does not work with the FSA K-Force Light, there ends up being a space of about 1-2mm when you try and tighten down the crank bolt.
That is surprising as we have 2 FSA K-Force Light compact and 1 standard SRM and none of them work with anything but the FSA BB86 and I have tried Shimano, Enduro, and Rotor.


on what bike?

Image

Image

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ms6073
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by ms6073

Our SRM's are 2010 and one 2011 and are installed on Giant TCR Advanced SL frames and while I don't have any Shimano road cranks, I have used digital caliper to measure the spindles and found the FSA K-Force Lite and SRM K-Force Lite spindle diameter to be ~1mm larger than the inner diameter of both the Shimano and Enduro BB86 bearings I have tried. Since the Shimano bearing cups are made of delrin, I have even tried swapping out the Shimano bearings for the FSA bearings but found the width of the Shimano delrin cups to be too wide thus not proving enough clearance of the spindle splines thus the nds crank arm could seat all the way and could not be properly torqued.
Michael - The Anaerobic Threshold is neither...

gn1tmac
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by gn1tmac

Image

thats why you can't use the fsa bb86 press fit, not even a wave spring washer + crush washer could fill that space and eliminate lateral play and provide correct chain line spacing

by Weenie


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ms6073
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by ms6073

Based on my experience with FSA's carbon cranks and BB86, that image would indicate to me that possibly the bottom bracket shell on the frame is a tad too wide (maybe ~2mm or so). Below is my FSA K-Force Lite SRM installed on my TCR because with the older FSA red alloy ceramic cups or the new delrin ceramic cups I installed over the weekend, with the nds crank bolt tightened to where the nds crank-arm is fully seated on the end of splines, there is a slight deformation of the wave spring washer.

Image
Michael - The Anaerobic Threshold is neither...

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