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I'm beating myself over the head after trying to mount an FSA Gossamer crankset into a Shimano BB. My MegaExo BB had developed play, and drag, and squeaking, so I thought I'd replace it. Bought the BBR60 cups, got the TL FC-25 adapter, and torqued it all down properly.

But the spindle is way too tight in the BB. Apparently FSA's idea of "24 mm" is noticeably larger than Shimano's. I've read multiple people online stating the combination works fine but that it might be "a pretty tight fit". (I should've stopped when I realized how difficult it is to even get the crank started through the first hole.) So I forced the spindle through, and without even putting the NDS crank on the other side, there is noticeable drag. I'm guessing the oversized spindle is putting undue radial pressure on the bearings and preloading them like that.

I'd take the loss as a lesson, put in my old MegaExo BB, and try to find a replacement for it (or find a Shimano crankset). I'd even accept just sticking with the BBR60 since the drag between it and the MegaExo is about comparable.

But the crank is stuck in a position that's neither here nor there (see picture below). I can't get it completely in and it won't budge if I try and hammer it out. Is there anything I can do here at all to either remove it or mount it completely? As-is, it doesn't seem it would budge even on the road, but it also completely ruins the chainline.

enter image description here

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  • I'm expecting a visit to the LBS is due, if this is salvageable at all. Shame, too, because I really liked this one. I guess that's the price of stupid.
    – jayded-bee
    Aug 22, 2022 at 9:38
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    Welcome to the world of F Shifts like Ass: "Let's use a non-standard bearing size so we can sell $20 bottom brackets for $70" Aug 22, 2022 at 10:33

1 Answer 1

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Yes, the problem exists. For some unknown reason, some of FSA’s “24mm” spindles are actually 24.07mm in diameter. Hence, they don’t fit well into Shimano’s 24.00mm system. You need the correct FSA BB to continue using those cranks

As for removal, apart from the usual oil, heat, and bigger hammer, you could also try an open-ended BB wrench if you have one available. You should be able to slip it over the exposed part of the crank spindle and unscrew the BB cups. The cranks will be extracted from one side of the BB at least using this method.

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    For some unknown reason Compare the pricing of an FSA bottom bracket to a Shimano one - and despite the price, the FSA one is a POS with about 1/3 the life of a much-less-expensive Shimano. I've had one FSA crankset - never again. Aug 22, 2022 at 10:36
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    @AndrewHenle Words can't express how this comment is simultaneously funny, sad, and relatable. Ultegra BB was 18€, cheapest MegaExo I can find is nearly 50€. I guess I'll cough up the dough for a Shimano crankset when I get the chance, but right now I'll concede defeat and get a LBS to deal with this.
    – jayded-bee
    Aug 22, 2022 at 11:35
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    @AndrewHenle I was trying to be charitable :) I agree that a simple Shimano setup is the far better way to go.
    – MaplePanda
    Aug 23, 2022 at 2:41
  • For the sake of posterity, now that the situation has been resolved and as much as I dislike this crankset, the bearings in my MegaExo BB are a standard 6805-2RS. Item code MR066 to be specific, but I think any one will fit: most 24 mm BBs use something similar. Point being, it seems that the plastic cap/spacer over the top of the bearing is what really holds the axle. It would appear that the Shimano and FSA plastic caps have different internal diameters, in line with your comments about the different axle dimensions.
    – jayded-bee
    Sep 6, 2022 at 21:45
  • Since these caps are relatively easy to obtain, it might be possible to use a Gossamer crankset with a Shimano BB (or vice-versa) if the spacers are replaced. As it comes from the factory, however, a SM-BBR60 is so tight on a FSA axle that the friction sips quite a bit of power. Also, wrt to the comment about the lower failure rates of the bearings Shimano uses: The Ultegra BB I purchased is purposefully made so that replacing the bearings on your own is impossible. The FSA BB is fully serviceable in this regard, if one has the right tools to pull and press the bearings into the cups.
    – jayded-bee
    Sep 6, 2022 at 21:45

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