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Old 09-28-11, 08:57 PM   #1
matimeo
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FSA External Bearing Crank Adjustment

My new bike has the following crank: FSA Gossamer MegaEXO External Bearing

Bike came from bikes direct. I've never played with one of these before so I didn't disassemble when I put the bike together (didn't have the tool). When I was at the LBS I bought the tool to remove it. I noticed a lot of clicking the last few days when riding that I had a hunch was coming from the BB (only happening when on the bike, mostly when pumping harder). I took it all apart tonight on a whim, regreased and reassembled. (By the way, it was mostly greased ok, but the bearing cups had cheap greenish lube that seemed flaky and dry- maybe that's what it's supposed to look like, but I didn't think so).

After reassembling while the chain was still off, I spun the crank arms. With a good throw they would spin around a couple of times (2-3) and stop. I thought maybe they should spin a little more freely than that. They didn't bind at all or feel like there was any noticeable resistance, but didn't seem to spin completely freely. So my question I guess is if I might have tightened the bearing cups too tight? I cranked down on them fairly hard, but not more than once they didn't move with a decent effort (sorry for the terrible description) I noticed the one on the left seemed a tad loose when I disassembled. The instructions that came with the bike for the crank said to tighten to 355-445 in. lbs., which seems like a lot. Can anybody with more experience than me on this give me some feedback? Buy a torque wrench or not that big of a deal? I just rode it around the neighborhood and didn't hear any clicking.

Thanks,
M
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Old 09-28-11, 09:09 PM   #2
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2-3 times is about all those external BB do. New and "improved" is not always better. Try old and square if you want to spin.
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Old 09-28-11, 10:29 PM   #3
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External-bearing BBs like the FSA MegaExo tend to have "seal drag" when new. Give it a couple hundred miles and see if it loosens up.

The user reviews on the web don't exactly shower praise on the FSA MegaExo BBs though. I would suggest that if the FSA MegaExo BB starts to crap out on you after a few hundred miles, replace it with a Chris King BB (they have one that is compatible with FSA MegaExo cranks).
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Old 09-28-11, 10:55 PM   #4
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FSA cranks have no real way to adjust the pre-load. So if you overtighten the crank bolt, it side loads the bearings in the BB and you get more friction. Having said that it's friction on an unloaded crank and there is a lot of debate as to whether this means anything.

If it isn't clicking, and there is no play in the axle then you should be fine as is. Generally I tighten the crank bolt down to the first sign there is any friction so long as there is no side to side play in the axle.

I prefer the Shimano system as it separates pre-load and crank attachment.
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Old 09-29-11, 07:47 AM   #5
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That 355-445 inch-pound recommendation is the torque used to install the cups in the frame, not to pre-load the crank arms.
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Old 09-29-11, 08:11 AM   #6
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Quote:
Originally Posted by matimeo View Post
.......the bearing cups had cheap greenish lube that seemed flaky and dry.......
I'm pretty sure that's loctite you're talking about there. Straight out of the box on a new FSA bb, the threads have green loctite on them.

Some of the least durable bb bearings ever, FWIW.
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Old 09-29-11, 08:15 AM   #7
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I had a one of those cranks swapped it out after 4000 miles for a Shimano 105. I was not having your issue just poor shifting to the big ring. The difference was day and night. External bearings are great I would buy a new crank and BB, could even get an Ultegra 6600 for maybe less than 150$. Believe me it will be better and they do not just spin like a top 2-3 is good.
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Old 09-30-11, 12:48 PM   #8
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Thanks everyone. Your feedback has been extremely helpful, as always.
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Old 10-02-11, 07:02 AM   #9
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Pain has it correct.
The seal drag on the new external bearing BB really slows things down.
Supposedly, the ceramic bearing versions spin a lot better..but it'll cost ya.
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Old 10-02-11, 07:06 AM   #10
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Whoops..didn't see the issue regarding tightening.
As a FSA owner (Team Issue '08)who HAD his crank arm come off on a ride (and didn't have the allen wrench to tighten=a 6 mile walk back to the vehicle)and who had a friend have his come off on a century ride, might I add..
Tightening and locktite ARE critical.
I had the 'best in the area' LBS do mine and have them go over that issue every spring before the ride season starts. This is one of those areas (tightening to the correct specs) I'd prefer to let a pro do.
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Old 10-02-11, 11:27 AM   #11
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Thanks for bringing that up. I'll need to make sure I check those periodically.
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Old 10-02-11, 12:32 PM   #12
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The Gossamer crank arms themselves are fine. A little heavy, bu they get the job done. I am not a fan of the chainrings that come on the bike nor am I a fan of the bottom bracket. I much prefer the Shimano counterparts. You can replace the FSA bb with a shimano one for much cheaper than a Chris King for improved durability.

I am not entirely convinced that the seal drag does anything. I overhauled some MegaExo cups recently and they had seal drag that subsided after a couple hundred miles. That BB is still going strong after 2000 miles. YMMV.
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Old 10-03-11, 11:49 AM   #13
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The external FSA BB that came with my FSA Gossamer crank went 32,000 miles with no problems. Was still smooth, but I changed it out as preventative maintenance. I replace it with a Shimano 105, but only because it was quite a bit cheaper. The 105 was very stiff initially, but when I replaced a chain about 4000 miles later, it spun very freely.

If the bearing feels smooth (not gritty) by hand and has no play, it's fine. A lot of crank play comes from not getting the left-side crank arm on properly.
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