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Discussion Starter · #1 ·
I have an FSA (K Force?) carbon crank (SRM). Problem seems to be that if I get the bolt sufficiently tight, the crank is bound up a little, but if I loosen so that the crank spins freely, the bolt is barely tight all and has worked itself loose. I change it out quite a bit (different bottom bracket on each bike, so moving only the crankset), moving it from bike to bike, 3 in all, so this comes up frequently. Can't be a "set and forget" kind of solution, I don't think.

Anyone have any thoughts on this? Thanks.
 

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Yes, I had the same problem with both FSA K-Force and FSA SRM Pro cranksets but from what I have seen, refacing the bottom bracket may not resolve the issue.

For the OP, See this thread: https://forums.roadbikereview.com/showthread.php?t=127002

But to sum it up, when installing the bottom bracket are you installing with the inner alloy sleeve? If so then the problem is most likely that when the spindle is inserted into the bottom bracket, there is not enough of the splined end of the spindle protruding beyond the 'face' of the plastic bearing dust cover. Remove the non-drive side crank arm and examine the spindle - if you cannot easily see the end of the splines, then you will have a problem with binding under proper crank bolt torque.

When FSA introduced the K-Force light compact crankset, they updated the design of the MegaExo bottom bracket by eliminating the use of the inner alloy sleeve (#3 in the image below) and the rubber bushing/spacer (#5). The result is that the width of the bottom bracket is reduced and to prevent lateral play, FSA added a steel wave washer to which serves to keep pre-load on the system. For non-K-Force Light users, I have found that if you remove the inner alloy sleeve and the rubber frame bushing, when you insert the spindle you will now be able to see the end of the splines on the non-drive side crankarm and that when tightening the crank arm crank bolt, most likely the bolt will bottom at the proper torque and should no longer be able to come loose during use. Note that for some framesets, this 'fix' may/can introduce lateral play that can be eliminated with the blue teflon o-rings (#8) FSA supplies with the crankset.

MegaExo crankset:
 

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thing to check...

If this problem only occurs with one bike and not the others, it would suggest that this bike has a wider combined width of the BB shell and bearings.

I assume that the FSA left crank arm actually bottoms out against a shoulder on the spindle, so the fixing bolt can reach a specified torque and hold the left crankarm in place. If it can't reach this shoulder, then the problem is what I've desscribed. Some width check with a micrometer might prove this out. You need to figure out if all of the problem is the BB shell width or also involves the BB cups and bearings.
 

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Discussion Starter · #5 ·
thanks

Good info.

Happens on all 3 bikes.

The inner sleeve (3) is not structural? No risk of harm from not using it?

The inner rubberized washer (5) I find typically smashes and buldges out. I have tried with and without.

The outer little washer (8) I have used and not, also, experimenting. Will try this combination with no sleeve.

Thanks.
 

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C-40 said:
You need to figure out if all of the problem is the BB shell width or also involves the BB cups and bearings.
Speaking from the standpoint of a consumer who owns bikes equipped with the FSA SRM Pro, and K-Force and the wifes bikes which both have the K-Force Light compact megaexo cranksets, typically when riders complain about loosening crankarms or binding crankset, the problem is usually the result of the inner sleeve. The inner sleeve is too wide and causes the length between the outer faces of the bearing cups to be to be to wide and when installed per FSA's instructions, on some bikes the non-drive side crankarm will not seat properly often resulting in too much pre-load/binding of the bearings. When the inner sleeve and the rubber bushing are removed, the width is reduced and the non-drive side crank arm will then seat properly on the splines on the spindle.

Fixed said:
The inner sleeve (3) is not structural? No risk of harm from not using it?
If you compare your MegaExo bottom bracket to the re-designed MegaExo that comes with the K-Force Light compact crankset, you will see that the sleeve and bushing have been removed and a wave spring washer replaces the teflon o-ring on the non-drive side to eliminate lateral play. What I found was tht with out 07' Giant TCR Advanced ISP framesets, using the wave spring washer produces too much preload and I ended up using the teflon o-rings instead of the wave spring washer.
 

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Discussion Starter · #7 ·
data

Ok, pulled off the crank and bottom bracket. This is the FSA ceramic model bb.

The outside dimension of the Cervelo P2C bottom bracket housing is exactly 68 mm, measured with a digital caliper with resolution to .01 mm.

The inside dimension of the bottom bracket is 69 mm, with either or both of the outer and/or inner sleeve installed.

Reinstalled the bb, and sure enough, there is about a 1 mm space between the flange of the bb cup on the left side and the frame. Installing the crank, it seems to bottom out and bind up before the bolt is tight.

So, I tried not using either the inner or outer sleeve, and installed only the bb cups on each side. Installed the crank again, and full tight, there is no binding, and no play (not using any of the washers).

So, should this work? What do those sleeves do, anyway? I assume they don't go to the trouble of including them for nothing.

Thanks.
 

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Fixed said:
So, should this work? What do those sleeves do, anyway? I assume they don't go to the trouble of including them for nothing.
I think the inner sleeve was intended to prevent overloading the bearings but as you and I have both found out, that is not the case. The outer sleeve is to prevent foreign matter intrusion into the bearing cups and some have added that to some extent, the outer sleeve was supposed to aide in the alignment of the external bearing cups. Our time trial bikes (Giant TCR TT Composite) with Ceramic MegaExo bottom brackets have been running sans inner and outer sleeves for more than a year and have suffered no ill effects but they are not used everyday as are our road bikes. I have also read that some have even traded out the MegaExo bottom bracket for the Dura Ace external bearing cups which do not use a center sleeve with no ill effects.
 

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Thanks for the heads up on this solution. I was building up a bike using the Mega Exo cranks on an Italian threaded BB and ran into this same issue of the non- drive side arm binding the bearings if properly tightened to recommended torque. My BB shell measured 70mm, but after reading this thread, I removed the shell spacer (5), and blue o-ring (8) along with the inner sleeve (3), then torqued the NDS arm to specs and everything spins freely with no side play.
 

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Discussion Starter · #10 ·
good to know

ms6073 said:
I think the inner sleeve was intended to prevent overloading the bearings but as you and I have both found out, that is not the case. The outer sleeve is to prevent foreign matter intrusion into the bearing cups and some have added that to some extent, the outer sleeve was supposed to aide in the alignment of the external bearing cups. Our time trial bikes (Giant TCR TT Composite) with Ceramic MegaExo bottom brackets have been running sans inner and outer sleeves for more than a year and have suffered no ill effects but they are not used everyday as are our road bikes. I have also read that some have even traded out the MegaExo bottom bracket for the Dura Ace external bearing cups which do not use a center sleeve with no ill effects.
This one is the time trial bike, so it won't see tons of miles and almost no bad weather. Besides, being ceramic bearings, aren't they supposed to survive everything short of a direct nuclear blast?

Don't most of the new bb designs rely solely upon the bb housing -- the frame, for alignment, with no sleeves? Don't know why this design should not work as well.

The bb spins sooo much more freely without the sleeves, yet the bolt is fully tight, and still no side play. I do have a concern that a vital part of the system seems to be the plastic bearing covers between the bearings and the bb axle and cranks, and I wonder if they may wear prematurely, compared to designs where the bearings directly meet the metal axle and metal bb cups. I wonder if this could be exacerbated by not using the sleeves, but it's pure speculation.
 

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Discussion Starter · #11 ·
works great

ms6073 said:
I think the inner sleeve was intended to prevent overloading the bearings but as you and I have both found out, that is not the case. The outer sleeve is to prevent foreign matter intrusion into the bearing cups and some have added that to some extent, the outer sleeve was supposed to aide in the alignment of the external bearing cups. Our time trial bikes (Giant TCR TT Composite) with Ceramic MegaExo bottom brackets have been running sans inner and outer sleeves for more than a year and have suffered no ill effects but they are not used everyday as are our road bikes. I have also read that some have even traded out the MegaExo bottom bracket for the Dura Ace external bearing cups which do not use a center sleeve with no ill effects.
Removed the both inner and outer sleeves on two of three bikes with FSA bottom brackets (same SRM crank moved around). Works wonderfully, so far. Very smooth, and no detectable looseness. Will report back long term.
 

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Purplecu22,

I just removed the two sleeves: inner and outer and rode about 50 km since...no problem. See, I think the role played by those sleeves has been well explained previously in this thread. First, the inner slleve. My best understanding of the inner sleeve use is to prevent overloading the bearing inner race when torquing the the left crankarm in place. However, It can't really, happen because, at my experience, your each the appropriate torque on the bolt BEFORE the crank arms start to push against the bearing inner races (the load allowing to reach the torque is from the press fit of the spindle splines). Above that, this inner sleeve can cause bearing overloading itself and causing binding just by torquing the bearing cups in the frame if this one is slightly narrow, so it causes the problem that it supposes to avoid. My BB shel is exactly 68 mm and this inner sleeve caused binding just by torquing the cups (even with the crush washer). So to recap, it can't prevent bearing overload by torquing the bolt because the load is created by the spline pressfit, if the BB shell is slightly larger so the slleve does not touch the bearing inner races it's then useless, if the BB shell is slightly narrower, the sleeve causes bearing overloading and binding just by torquing the cups. What a good design ! Not only it causes problems, it does not solve any and add weight. OK for the inner sleeve. About the outer sleeve: My best understandinf of the outer sleeve use is to prevent bearing contamination by the BB internal such dirt and water. It's true if your BB shell is open to other frame tubes or the exerior. Mine is completely closed and sealed, so no big deal. The second role would be to control the width between the 2 cups by allowing a specific distance for which the spindle must protrude on the left hand side in order to prevent lateral play. But if your BB shel is correctly faced at 68 mm, lateral play won't be a problem or well controled by the blue orings, rubber crush washer and even the torque on the bolt (remember the spline press fit, higher the torque, tighter fit, left arm deeper intrusion on the spindle). Forget the pseudo outer sleeve third role of helping the alignment of the cups: the sleeve is connected to the cups by slight fit with rubber oring, so it can't align anything! So to recap the outer sleeve role, if your BB shell is sealed and not connected with other frame tubes and well faces at 68 mm, you don't need it either.

That's why and get both sleeves out of my bike.
 

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Nicklaus said:
lateral play won't be a problem or well controled by the blue orings, rubber crush washer and even the torque on the bolt (remember the spline press fit, higher the torque, tighter fit, left arm deeper intrusion on the spindle).
:idea: Wanted to insert something here to make sure it is not overlooked. With a bottom bracket shell of proper width and adequate facing (most are fine out of the box), when tightening the crank bolt on the non-drive side crankarm, the splines of the spindle should 'bottom' on crankarm at about the point specified torque is reached. In my experience, when tightening the bolt and the crankarm bottoms as expected, continuing to apply torque to the bolt when the crankarm is fully seated on the splines will quickly result in a cracked/broken crankarm bolt! :mad2:

If you want a way to test the installation - whether using the older BB-8000 MegaExo bottom bracket or the newer BB-8200 Ceramic MegaExo bottom bracket supplied with K-Force Light and NeoPro TT cranksets, before installing the bottom bracket, press the bearing cups onto each end of the outer sleeve and then insert the crank spindle into the bottom bracket. Observe the splines at the point where they protude from the non-drive side bearing and make sure that the point along the spindle where the splines end (spindle splines end and smooth shaft surface starts) is visible beyond the bearing cup. Now using this as a reference for when the bottom bracket bearing cups are installed in the frame, inserting the spindle should produce the same result.

The point where the splines on the spindle end should be visible - if this is not the case, then the non-drive side crankarm will not seat completely when the bolt is tightened and as many have experienced, will most likely come loose quite soon. Finally, you can test the installation once the crankarm bolt is tightened to specified torque, spin the crankset. If the crank does not turn freely - making at least 3 or more rotations - then the bearings are binding and the crankarm is not seated all the way onto the spindle splines.
 

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Discussion Starter · #15 · (Edited)
working

I have the SRM/FSA K Force carbon crank set up to work on three different bikes, a Bianchi 928 SL carbon, a Cervelo P2C (with ceramic bb), and a Soma Smoothie ES (for commuting). Each has it's own bb, and I just move the crank arms to each bike.

Tightening the crank arm down bottomed out and bound up on both the Bianchi and Cervelo, so I removed both sleeves. Now, I can tighten the crank fully, and there is no binding at all, and no looseness detectable at all, either. Very smooth and solid. For some reason, on the Soma, the crank tightens fully with no binding with the sleeves in place, so I left them there. This is my "rain bike" anyway, so I guess this is fortunate.

No problems whatsoever, after plenty of hard use.

For those who have had problems with the FSA bearings failing, I wonder if it was because of binding due to the sleeves not allowing the bearing cups to be narrow enough?
 

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FSA Mega Exo Problems

My FSA bearings failed within one year. July 2008, there are no replacement FSA english BBs available in the market (don't know why). Therefore, I bought the ceramic Enduro bearing kit and had them properly installed. These bearings are different in that they do not incorporate a plastic outer sleeve and are sized to press into the cups without the sleeves albeit they do have outer washer rings to try and keep out water (installed). On first tightening to torque, the crank binded. I read the posts here, I removed the two outer o-rings and the non-drive inner cup rubber washer and the inner aluminum sleeve and, the bearings still bind. My BB shell measures perfectly at 68mm.

Havn't ridden for a week, am really pissed with FSA as they won't talk to the customer. Any further remedies to making this work (alot invested now, no moula left to buy another crankset). I am also on my 3rd front FSA compact derailleur in 12 months as it keeps binding.
 

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Therefore, I bought the ceramic Enduro bearing kit and had them properly installed. These bearings are different in that they do not incorporate a plastic outer sleeve and are sized to press into the cups without the sleeves albeit they do have outer washer rings to try and keep out water (installed).
Hope that works out for you. For me:

1) Original MegaExo BB: bearings shot after 3000 miles.

2) New cups with Phil Wood bearings: bearings shot/bad lateral play after 3000 miles.

3) FSA Ceramic bearings MegaExo BB: bad lateral play after 3000 miles.

4) Ultegra SL crank and BB: I'm now happy, and no problems.

For those who have had problems with the FSA bearings failing, I wonder if it was because of binding due to the sleeves not allowing the bearing cups to be narrow enough?
No ida what the trouble was, but I just got tired of giving FSA money. For me, BB #1 came on the bike, #2 was installed by one of the best wrenches in my area, and #3 by a different, really good mechanic. #4 and crank was installed by me in my kitchen in about 5 minutes.
 

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Ditto that. Trashed the 2nd Megaexo that failed on me, bought a Dura-ace crank / BB and have been spinning ever since.
 

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Guys, just to give you an update on my latest Megaexo bottom braket BB-8000 without both sleeves (inner and outer). To date, everything is fine except that I noticed that the metal-rubber washer installed between the frame BB shell and the bearing cup (on the left side) is "sliding out" the assembly. This caused the bearing cup to move slightly toward the frame and result on a slight lateral play. I took care of the lateral play by screwing the crank bolt by half a turn, but here is my thoughts on why that happened: I think the rubber-metal o-ring is not design to be squeezed by the total amount of torque used to install the bearing cup. This is where the outer sleeve comes in...when installing the cup, the cup contact the outer sleeve and a limited amount of torque squeezes the metal rubber washer since the remaining torque compresses the sleeve. This limited torque squeezin the o-ring prevent it to "slide-out". This is my ubtade according my own understanding. Any other thoughts ?
 
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