FSA Bottom Brackets - are they different than Shimano?

[FastforaSlowGuy]

The threaded FSA bottom bracket on my CX bike is shot. I've got some Shimano ones laying around, but I recall reading somewhere that FSA cranksets are funky in some way, so that they aren't really cross-compatible (maybe it was a spindle length issue?).

Before I spend my evening tinkering with this, I thought I'd see if my fuzzy recollection is even remotely accurate.

[thegunner]

i thought they were identical - 24mm throughout the spindle. i've mixed a gossamer in with a shimano BB before and that was fine...

[gdw]

What type of FSA bottom bracket do your cranks use? If it's not a square taper bb it might be proprietary and not compatible with anything Shimano offers. These links might be helpful:

http://www.bikeman.com/bicycle-repair-tech-info/bikeman-tech-info/1599-bottom-bracket-types

http://www.bikeman.com/images/stories/RepairTechInfo/externalbbfitchart.pdf

[oliver1850]

I've used Shimano cups with aluminum FSA cranks like Gossamer and Energy. I believe the carbon cranks have a different diameter spindle and won't work with Shimano cups.

[kramnnim]

Paging Exonerv...iirc he said the carbon cranks use a narrower BB.

The alloy ones...seem to have a slightly larger spindle than Shimano, I had to beat a Gossamer into Shimano cups.

[Exonerv]

Just went through this and ended up ordering an FSA 8000 series megaexo BB off ebay for $40 for my K-Force carbon cranks. From my reading on the Zinn site which included a letter from FSA, the carbon FSA cranks require a slightly narrower (1mm) BB. According to FSA the alloy cranks use the 6000 series BB which are compatible with Shimano.

Found it...

http://velonews.competitor.com/2009/01/bikes-and-tech/technical-faq/technical-qa-with-lennard-zinn-the-tall-mans-dilemma_86337

[oliver1850]

Mark, any chance there was some of the fiber bushing that FSA uses on their bearings remaining on the spindle? I've seen that bushing get worn down to almost nothing but any remaining on the spindle might have caused you difficulty in getting the crank all the way in.

There are several aftermarket replacements available branded GUB, Sars, etc.

http://www.ebay.com/itm/WORLDs-LIGHTEST-87g-BSA-68mm-Road-Sealed-Bearing-Bottom-Bracket-BB-Shimano-FSA-/281108990627?pt=US_Bottom_Brackets&hash=item417366caa3

[kramnnim]

No, it was just the steel spindle. It fit into the FSA BB perfectly, but not the Shimano. I should have tried a Shimano crank in the FSA BB...

Edit: Various people on forums have had the same troubles... For example, http://www.bikeradar.com/forums/viewtopic.php?t=12860888

[FastforaSlowGuy]

I think that VN article is what I was recalling. Mine is a carbon crank (K-force or SL-K). The stock BB had this alu sheath between the cups that, combined with the stock spacer, made it too wide for the crank. The result (which others on the interwebs have also documented) is a crankset that is either all bound up or nearly falling off. (FSA fixed the issue in later generations by using a wave washer.)

I could make the DIY tweaks to make it fit, but the bearings are already pretty shot, so I'd rather replace it. Looks like I'll be buying another crappy FSA BB, though.

[Exonerv]

I too reluctantly caved to FSA's proprietary nonsense. As if we didn't already have enough to keep up with when it comes to BB standards.

I elected to pick up a new wave washer ($4 eBay) at the same time I ordered the FSA 8681 English BB.

[oliver1850]

Another FSA would be my third choice. I'd try Shimano first. If that doesn't work, I'd go with one of the aftermarket choices.

[CiclistiCliff]

Shimano uses 24mm spindles.

FSA uses a 24.2 or 24.3 mm spindle.

aka. not compatible. can be done, but not recommended.

[Exonerv]

To complicate matters further, my K-Force crank has no way to tension the bearings except at the crank bolt. Torquing the crank bolt to spec overtensions the wider Shimano BB bearings leading to premature failure of the non-drive side bearings.

[oldpotatoe]

To complicate matters further, my K-Force crank has no way to tension the bearings except at the crank bolt. Torquing the crank bolt to spec overtensions the wider Shimano BB bearings leading to premature failure of the non-drive side bearings.

Geeez, Louezze, nothing personal, and I know it ain't cheap but just get a shimano or Campagnolo crank and be done with it.
Better chainrings, better BBs, better bearings, better better, etc...

[FastforaSlowGuy]

That's exactly where my head was going as I pondered dropping $40 on a new FSA BB. I inherited this stupid thing, so I'm stuck with it for a little while. But once I'm done with CX (which could be after 1 race, who knows), I'm putting it on the block and getting a Shimano crank.

[Exonerv]

Yep...same here. The FSA K-Force crank came with the frame, and I figured for $40 I'd give a compact another try. The darn thing does look pretty nice. In the meantime, I'm sourcing a DA 172.5 7800 or newer crank.