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Discussion Starter · #1 ·
I am helping a friend set up a bike and picked up a FSA SLK crankset.

The instructions reccomend using Loctite 641 on the interface between the left crankarm and spindle.

I can understand Loctite for threads but it seems kind of hokey that Loctite is required there. It almost sounds like they are making up for some poor tolerances.

Anyone have experience with this?

Its a nice looking crank but if they had problems I will return it and get something else.

 

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Poor tolerances is giving FSA a compliment. With or without the Loctite the left arm may loosen and you won't be able to tighten it enough to keep it from moving. I would call it an engineering defect more than a manufacturing problem. I had an FSA crank before Loctite was recommended. The left arm started to move and there was no way to tighten it enough. FSA did replace the crankset under warranty with the new "glue it" and it won't move instructions. I never installed that crank.
 

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I've got 2 of these cranks. First, I ground back the bushings (inside spacers) and caps of the MegaExpo bottom bracket so I could tighten the sh!t out of it onto my bikes frame without putting pressure on the bearings. Took some precise measuring to do this correctly. This narrowed the entire bracket a bit, but allowed me to tighten very well the left crank onto the axle, again, without pressing against the bearings as the crankarm pushed up against the end of the fingers on the spindle, not the bearings. However, I did need to leave off the very narrow washer on the left inside crank arm, otherwise it would push up against the bearings and cause resistance. In the end, this was a pain in the butt, but the crank turns very easily, smoothly and silently, and it is tightened on with near gorilla force and I do like the looks. However, next time I get an Ultegra SL (which I also have) as it just works. Simple to install and the left crank arm pinch tightens onto the spindle, no pressure on the bearings and its on very securely.
 

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Discussion Starter · #7 ·
Thank you

Thanks for the info JimP and tbgtbg!

It is a great looking crankset, but I am installing this on a friends bike and I dont want him to have any hassles now or in the future. Even if it did install and stay tight, I dont want him to have to do anything special if he or a shop ever needs to remove it and reinstall later.
 

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Its a nice looking crank but if they had problems I will return it and get something else.
As a former owner of one of those, I'd recommend getting a different crank. I can't believe the amount of time and money I wasted trying to fix, as JimP points out, a poorly designed crank.
 

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I have had a FSA SLK (octalink) crank for a couple of years, moved from a road frame to my cross frame. Followed the Park Tool recommendations for installation. It has taken a beating on the cross frame but never needed re-tightening and I never put on loctite. The only thing that has failed is the FSA BB.

I would say put it on make sure the bolt is tight and ride the hell out of it. Check the bolt for tightness in a couple of weeks.
 

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So the new fix is called Loctite. I had that crankset on my Tarmac. It was in the shop multiple times for the crankset loose, creaking, bearing damage. I fedup and replaced it with Ultegra crankset.
Bike shop and I could never get the creak out of it. First FSA send us metal/rubber washer, but that did not let us tighten the crank, then they recommended a spacer on the MegaExo BB, After that, when they tightened the left crankarm it put too much side pressure on the bearings and they failed. Then they recommended additional handmade teflon washer which worked for 1 month but worn out.
So you get the picture. My current Ultegra cranks are trouble free for 7,000 miles, the other set has 17,000 miles and no problem.
Main problem with this good looking FSA crankset is that one bolt both tightens the crankarm to the spindle and also sets the tightness of the whole assembly. So if you want your crank arm tight you will most likely put too much pressure on bearings and crash the blue teflon washer and crankset will be binding, if you want just right play in crank/BB assembly your left crankarm will loosen. to accomodate the tolerances they use teflon washer which fails after couple months. I guess now they are recommending to set the correct tightness in crank/BB assembly and use locktite to prevent left crankarm loosening. BTW this problem is prominent to heavy 200lbs riders, lighter riders develop this kind of problem not as often, because they do not put as much pressure on the crank/BB.
I would say return it and get Shimano crankset from your local craigslist or Ebay if cost is an issue.
 

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if you do a search, there is a great post explaining how this crank works. You must see the bottom spindle lip (don't know how to explain it) sticking out of the BB. If you don't the crank will always come loose. I have 3 sets on 3 different kinds of frames never an issue with my cranks coming loose.
 
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