FSA BB-4000 MegaExo 19 bottom bracket review

FSA BB-4000 MegaExo 19 bottom bracket

My 2014 Specialized AWOL came with an FSA Omega MegaExo 19 triple crank and an FSA BB-4000 bottom bracket.  I bought the bike in October and in March I started thinking about doing some post-winter maintenance.   One of the things that I wanted to do was remove and examine the bottom bracket.  Since I was not familiar with outboard bearing bottom brackets, I did some research about the BB-4000 bottom bracket, and here is what I found out.

At the first glance, the BB-4000 looks just like a Shimano Hollowtech II bottom bracket. It looks the same and it takes the same tool to remove or install it.  You may get a warm, cozy feeling that you have something that is easy to service and replace.  Wrong!  The biggest problem is that, unlike Hollowtech II bottom brackets and cranks (and also unlike other FSA MegaExo bottom brackets and cranks), the BB-4000 is designed for crank spindle diameter of 19mm (whereas HTII system is for 24mm spindles).  As far as I know, the BB-4000 is the only bottom bracket on the market that can be used with 19mm crank spindle, and the Omega crank set that I got is the only crank set on the market with a 19mm spindle.

This means that you have a system that is only compatible with itself.  Good luck finding the BB-4000 or the Omega crank in stock at any local bike store; all the stores I phoned told me it was a special order item.  Not only that, but both FSA items are priced two-three times higher than comparable items from Shimano.  For instance, you can get a Shimano HTII bottom bracket for $23, but the BB-4000 costs above $60.

There also is a philosophical problem.  The Specialized AWOL is a touring bike.  Touring bikes are traditionally designed with components that are easy to replace even in a small town bike store.  What are the chances of quickly replacing the BB-4000 if it breaks down in the middle of a tour?  That’s right, zero!  Good thinking, Specialized, whoever made this design choice for the AWOL deserves a round of slow clapping.

And a special round of  slow clapping goes to the folks at FSA for creating this non-standard standard.  Good job guys, why did you do that?  Is the 19mm spindle that cheaper to make than a 24mm spindle?  Or, perhaps, the plan was to sell the system to OEMs so that consumers would be locked into this inferior system?

If you are reading this, the chances are that you got the 19mm MegaExo system stock on your bike, because I cannot imagine why anyone would install MegaExo 19 system by choice.  Rather than feed the system by buying overpriced bottom brackets, I suggest that you chuck both the bottom bracket and the crank set and replace with something more reasonable.  I bought a Shimano 105 series 5703 crank set with a matching HTII bottom bracket for just over $100 on Ebay.  This cost me less than replacing the BB-4000 twice, and it gives me peace of mind knowing that I am using parts that are easy to replace at any moment, should they break.

p.s. When I replaced the FSA BB-4000 with a Simano HTII bottom bracket, I discovered that the bearing in the left cup of the BB-4000 was completely seized.  The crank was rotating in the inner diameter of the left bearing like in a sleeve bushing.  This happened less than six months after I bought the bike, but to be fair I rode it though the winter in Toronto, which means a lot of snow and salt.  Not sure how indicative this is of the quality of the BB-4000 bearings.  Perhaps the HTII bearing would have seized the same way, it’s hard to know.  I’ll have to ride through the 2015/16 winter with the Shimano bottom bracket and find out.



  1. Thanks for this – came here after doing research on how my AWOL’s BB. Apparently, the FSA megaexo’s are huge pieces of shit.

    Mine has about 5000 miles on it and has play, can’t be adjusted and needs to be replaced.. with another overpriced, short lived BB. I’ve ridden for decades and literally never had a BB die so quickly. I think on the newer AWOLs Specialized changed up the BB.

    1. Yeah, the new 2017 AWOL comes with a Sora triple crank and a Hollowtech II bottom bracket. The 2015 and 2016 models still came with FSA cranks and bottom brackets.

      I am not sure whether a HTII bottom bracket would last much longer than 5000 miles, but at least a replacement is cheap, available in any bike shop, and very easy to install.

  2. …….I’d like to personally thank the design team at Specialized–Erik Nohlin and Recep Yeşil–along with the rest of the marketing team and FSA for producing a cancerous, terminal product whos end life coincidentally coincided with the release of the #imadesignerdouchebagveganfuckface Sequoia… to make an easier sell when “unfortunately your aluminum bottom bracket wasn’t greased when ‘you’ installed it at the factory and is seized to the frame…and then it stripped when we tried to remove it so the frame is ruined but we can offer you 10% off a new bike today only!”

    And on the subject, the Formula hubs are total shit too!

    1. That must be painful. Try talking to somebody higher up at Specialized or perhaps you LBS can help.

      I agree, those bottom bracket and crank were dead end products at conception at best, or borderline criminal at worst. No-one in their right mind would buy them unless forced to by OEMs.

  3. Stumbled on this post as I look at why the 4000 is so expensive compared to HTII. I have a 5800 crank lying around so I might as well spend the £10 on a HTII BB instead of the £40 for a 4000.

    Ludicrous how these are supposedly comparable.

  4. Glad I found this. I feel ya on this.

    Assuming I am also replacing the FSA crankset (105 5800) is the Shimano SM-BBR60 a direct replacement FSA BB-4000?

    1. Yes, the BBR60 should work, however, I have recently had “fun” with it.

      BBR60 has small diameter outer cups, but includes a plastic adapter to use the larger HTII cup removal tool. I thought that the adapter would work with the 16-notch BB removal tool that I already had (that tool worked with the FSA BB-4000, with whatever BB came as part of 105 5703 crank, and with whatever is considered a current Sora bottom bracket), but the plastic adapter does not fit it. I don’t remember right now, but the plastic adapter is either 1mm larger or smaller in diameter than all other external bottom bracket cups that I have had to deal with before. None of the three bike stores I tried had a tool that would either fit the cups of BBR60 or the plastic adapter that comes with it, but offered to special-order the original Shimano tool.

      I ended up having to buy a $30 metal adapter that fits the BBR60 directly in its inner diameter, and the “normal” HTII cup removal tool with its outer diameter, in order to install the BBR60.

      So, just a heads-up: make sure you have the right tool for BBR60 before you take your old bottom bracket out.

  5. I have the FSA BB-4000 MegaExo 19 bottom bracket on my 22 speed road bike. It is making noise after about 3200 miles, so I am going to replace it. You recommended a Shimano 105 series 5703 crank set with a matching HTII bottom bracket. Since I only have two chain rings on the crank, is there another crank set and bottom bracket combo that I should get – with only two chain rings?
    Thanks DJB

    1. My bike is 3×9, looks like you have 2×11. I have no experience with 11-speed road group sets, so I can’t offer a direct advice. You need to research which crank sets are compatible with your front derailer and shifter. If you have Shimano brifters, then I would probably look at the 5800 series crank sets, as they are for 11 speed system; the 5700 series was 10-speed, and I am not sure whether it will work with an 11 speed group (the distance between the two chainrings may be wrong).

      1. Great, n thanks, I have Shimano 105 shifters. I will go to a Shimano service center and ck with them. Thanks for your prompt response.

  6. I just replaced the megaexo on my AWOL. TBH, I think it was shot within a few months of having it. What a piece of garbage.

    I’ve replaced it with a shimano BB that cost like $25 and a crankset that was like $180. The bike feels so much smoother, it’s kind of astonishing.

    How Specialized sells a $1500 bike with such garbage components. The kid in the bike shop tried to get my to by a Salsa and i think he probably knew about the garbage components.

    Rear wheel, rear derailleur, bottom bracket, crankset. The rear wheel literally disintegrated from the salt(!(?))?

  7. Oh crap,

    Just visited this after getting this crankset (compact 50/34 with 19mm spindle) at a garage sale for 5 bucks, everything looking almost new. I was going to look for a compatible bottom bracket for a beater bike project I’m working on but damn these BR-4000 are expensive as shit. This is so dumb, maybe it would be possible to manufacture adapters for a 24mm HTII bottom bracket? This currently exists for HTII (24mm Right 24mm Left) -> Sram GXP (24mm Right 22mm Left) and it’s just a small piece of aluminium with a 22mm inner diameter that you press on top of the left bearing. This could be a low-cost solution but on the top of my head I don’t know if 24mm -> 19mm would be too big of a gap for an adapter to work correctly.

    Thanks for the article m8

    1. I sympathize. It would probably not make economic sense making those adapters, because the market niche is so small. Good thing is that you are only $5 in, so not too much invested.

  8. Looks like this isn’t limited to Specialized. My Cannondale Topstone 105 from 2019 ALSO came with this piece of work (looks like that’s still the case based on Cannondale’s website.) I’ve been hauling the toddler around for 2 summers now and MAAYBE a dozen days of dirt/mud cyclocross trails and the BB is cranky. Shot? No, but it’s starting to whine like it’s gonna die.

    Thanks for this post though. Clarifying this is a non-standard setup and that I’m also going to have to change my crankset saved me hours of frustration.

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