Crank install question...wavey washer

bikerboy337 · #1 02-25-2021, 06:08 PM

So I’m installing a 30mm bb386 crank on one of my bikes, swapping from another similar crank (going from AL to Carbon version). Bb is installed and everything worked perfect with my AL cranks. Pulled those and went to install the carbon ones, instructions are wavy washer on the NDS of the spindle. With the AL cranks, worked perfect, torqued the crank bolt to spec and off I went.

With the carbon ones (brand new in box purchase) I’m trying to install, if I put the wavey washer on as specd, even before the right crank bolt is tightening down, the system is too tight, drag galore on the bearings. By chance I took the wavey washer off and reinstalled, spins perfect and zero side to side play.

I’m I going to regret installing without that wavy washer? I know they are supposed to be used to take up any slack in the system but I tried 3 different times with it and it just dragged the system... without it, all seems good but I’m hesitant to run like that without the wavy washer... would love any input!

FYI, these are FSA cranks.. trying to install the SLK Light Modulars... the Energy Aluminum cranks installed in 2 minutes and ran perfect... with the wavy washer..

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cgolvin · #2 02-25-2021, 07:10 PM

Others will likely know better, but from my experience the alloy and carbon FSA cranks each require a specific bottom bracket -- they are not the same. If you are using the same BB as you had with the alloy crank then I suspect that you may need to swap it for a different one.

Check this thread and in particular the link in post #4.

bikerboy337 · #3 02-25-2021, 07:55 PM

So I figured this out today after a few calls to FSA... long story short, apparently their Modular Chainrings are not all cross compatible... who would have thought... i was using a 46/30 set of modular chainrings from an FSA Energy Crankset on my FSA SLK crankset, and the tolerances and tooling are slightly different... so... long store short, i guess the modular chainrings are not too modular... can only use chainrings from the same line, so SLK doenst work with energy, etc...

Reason i really went with these cranks is i liked the idea of an easy swap of rings, but its not so easy in the end...

Got it set up with the 48/32 rings the crank came with and works perfect... so strange...

jc031699 · #4 02-27-2021, 07:50 AM

Quote:

Originally Posted by cgolvin

Others will likely know better, but from my experience the alloy and carbon FSA cranks each require a specific bottom bracket -- they are not the same. If you are using the same BB as you had with the alloy crank then I suspect that you may need to swap it for a different one.

Check this thread and in particular the link in post #4.

That’s for the 24mm spindle cranks, these are 30mm which is typical for PF30 etc. For FSA it is MegaEvo, which uses spacers etc. I believe what the OP found is that the direct drive modular chainring assembly that he was using from a different FSA crank line was too wide to work with this set of arms. So maybe that is carbon vs alloy arms, maybe not, I’m not sure.

https://shop.fullspeedahead.com/en/f...520.1614429762

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dddd · #5 02-27-2021, 06:03 PM

If the chainline is good, arms in right planes, spider attachment solid, no free-play or drag and no clearance issues, all is good.

bikerboy337 · #6 02-27-2021, 08:22 PM

This was exactly the issue... from the explanation I received, the 2 aluminum cranks have modular chainrings that are compatible, and the 2 carbon cranks (SLK and K LIght) have modular chainrings that are compatible, but between the aluminum and carbon, "some" of the combinations dont work...

We had to look at the serial number on the modular chainrings to see what factory they were from to confirm what was and was not compatible...

found it strange, as online they discuss gossamer/energy/slk modular chainrings as if they are cross compatible... but alas they are not...

solved now, the setup works great... just want to grab another set of the SLK 46/30 rings now to be able to swap in for hilly gravel this summer at some point, but the 48/32 is perfect for now...

Quote:

Originally Posted by jc031699

That’s for the 24mm spindle cranks, these are 30mm which is typical for PF30 etc. For FSA it is MegaEvo, which uses spacers etc. I believe what the OP found is that the direct drive modular chainring assembly that he was using from a different FSA crank line was too wide to work with this set of arms. So maybe that is carbon vs alloy arms, maybe not, I’m not sure.

https://shop.fullspeedahead.com/en/f...520.1614429762

Sent from my iPhone using Tapatalk

jc031699 · #7 02-28-2021, 04:44 PM

Quote:

Originally Posted by bikerboy337

This was exactly the issue... from the explanation I received, the 2 aluminum cranks have modular chainrings that are compatible, and the 2 carbon cranks (SLK and K LIght) have modular chainrings that are compatible, but between the aluminum and carbon, "some" of the combinations dont work...

We had to look at the serial number on the modular chainrings to see what factory they were from to confirm what was and was not compatible...

found it strange, as online they discuss gossamer/energy/slk modular chainrings as if they are cross compatible... but alas they are not...

solved now, the setup works great... just want to grab another set of the SLK 46/30 rings now to be able to swap in for hilly gravel this summer at some point, but the 48/32 is perfect for now...

Some spider dimension voodoo going on. I’m not surprised, I had something similar with my Rotor 3D cranks where the spider was different / wider for Cervelo frames specifically and I had to ask for help from the guy that staffs Rotor’s US office.

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