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-   -   FSA Mega Exo- two parter (https://www.bikeforums.net/bicycle-mechanics/586355-fsa-mega-exo-two-parter.html)

Ranger63 09-18-09 09:54 PM

FSA Mega Exo- two parter
 
I'm running the Team Issue compact FSA crankset with the mega exo BB setup.
Has anyone else experienced the assembly suddenly comming loose?
I did a metric last saturday and cleaned the bike after the ride (so I can tell you the crank arms were not loose then)
I did a followup ride the next day thru hilly terrain.
Cleaned the bike up (its a ritual with all my bikes)and hung it on the rack.
Used my othr bike untill today.
About 3 miles into the ride my left foot feels like it's wobbling.
After 4 decades of riding tapered cranks and standing on em occasionally, I knew what the feeling was.
The locking bolt on these cranks apparently draws the entire assembly togeather which-if you're riding a carbon fibre bike- is touchy as to how much torque to tighten with.
I removed the bolt and noticed it had no locktite on the threads whatsoever.
Given it's a right hand thread on a left crank arm (which would be prone to loosening one would think)

Is this a common situation with these cranks?
Does anyone know what the torque specs are on the crank bolt (I tried FSAs site with no success in finding assembly specs..although I did find a part number for the cap that supposedly threaded in the left crank arm and covered the bolt)
Has anyone else used permatex blue on the threads?

Second question: While I had the bike down I checked the freewheel of the cranks (no chain on simply spinning them) and noticed the cartridge bearing taper cranks on my Paramount spun 50% free'r than the FSAs on the Motobecane.
Is there a spec for tightening on the outboard bearings??

Yes, I'm probably going to take the bike over to the best of the LBS's in my area (not cheap but very good) but-in case this situation ever rears it's ugly head again, having the specs and knowledge would really help.

operator 09-18-09 10:03 PM

1) You don't need loctite on crankbolts
2) It's not touchy just because you're on a CF bike. Even if you overtorque the bolt the only thing you're doing is mashing the crank together, you're not stressing anything on the frame
3) The bolts came loose because they weren't torqued properly, 45-55nm according to FSA

Here is the fsa torque pdf: http://www.fullspeedahead.com/downlo..._Cranksets.pdf

operator 09-18-09 10:08 PM

http://www.fullspeedahead.com/downlo...gaExoAlloy.pdf

39-49nm for bb cups.

DSchlichting 09-19-09 08:01 PM

I have one of these.
As Operator already alludes, torque specs should be followed religiously, as well as other instructions that FSA provides.
Early versions of this crankset were supplied with alloy crankarm fixing bolts. These should be replaced woth steel ones, and can be ordered from FSA directly.
My crank arm fixing bolts do have a strip of loctite material on them. Not sure that is a big deal or not. Correct torque is what's important. Speaking of loctite material, do check your instructions to see if the Loctite 641 retaining compund is required on the axle splines. This is not a threadlocking compound. I got mine on amazon.com.
Some newer FSA instructions include usage of a wave washer on the left side. These can also be ordered from FSA.
In my case, I have had no issues with anything getting loose. This summer, I replaced the original FSA bearings (after 2-1/2 seasons) with Chris King. All has been well, until last week when the crankset began knocking loudly every revolution. I have not yet had the time to completely diagnose WTH is wrong with this.

operator 09-19-09 08:06 PM


Originally Posted by DSchlichting (Post 9706676)
I have one of these.
As Operator already alludes, torque specs should be followed religiously, as well as other instructions that FSA provides.
Early versions of this crankset were supplied with alloy crankarm fixing bolts. These should be replaced woth steel ones, and can be ordered from FSA directly.
My crank arm fixing bolts do have a strip of loctite material on them. Not sure that is a big deal or not. Correct torque is what's important. Speaking of loctite material, do check your instructions to see if the Loctite 641 retaining compund is required on the axle splines. This is not a threadlocking compound. I got mine on amazon.com.
Some newer FSA instructions include usage of a wave washer on the left side. These can also be ordered from FSA.
In my case, I have had no issues with anything getting loose. This summer, I replaced the original FSA bearings (after 2-1/2 seasons) with Chris King. All has been well, until last week when the crankset began knocking loudly every revolution. I have not yet had the time to completely diagnose WTH is wrong with this.

That's just what the manufacturer says. Their official torque specs for their bb cups is ridiculously high compared with torque necessary from experience. I could be wrong though.

Ranger63 09-19-09 09:03 PM

FSA Torque Specs
 
Thanks for the link. Much Appreciated.
I see the missing part is called a pinch bolt (one can only wonder how the hell it came off without my hearing it )and I believe it has a spring washer behind i.
Looks like a LBS order on this as FSA isn't apparently responding to customer enquirys.


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