# What are Bottom Bracket Spacers for???



## Rhino4Five (Nov 5, 2009)

I am converting my double to a triple. The new crankset it a FSA Gossamer Triple MegaExo. Specifically, the bottom bracket is BB-6000 w/24 mm spindle diameter.

I think I need to insert 2.5 mm spacers between the bearing cup and center sleeve. Which side does this go on, and what is this used for? Does it only go on one side? I've looked at the tech docs, and I cant seem to figure it out. 

And while I'm at it, the BB is 68/70 mm. How can it be both? What does it mean? 

Thanks in advance.


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## Miles Tougeaux (Feb 16, 2011)

Some triple external bearing cranks do use a spacer on the non-drive side. I don't see mention of this being necessary on either of these tech docs:

http://erinabikeworxonline.com/downloads/MegaExo.pdf

http://www.fullspeedahead.com/stora...3_ZS080-FSA_BB-6000_4000_Road_Crankset_v5.pdf

Did you receive a spacer with your crank/bb?

68 = English bb shell
70 = Italian


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## Rhino4Five (Nov 5, 2009)

Yup, there was a spacer around the driveside bearing cup. This crankset and BB were previously installed, so I just assumed the spacer was installed between the driveside bearing cup and center sleeve.

I also was unable to gain anything from the tech docs. But thank you for looking them up.

Can anyone tell me when the spacers are used? That might help me figure out the installation.


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## durielk (Jan 8, 2011)

I got a used FSA mega external without instructions or spacers. I installed it and the whole crank would move side to side, left to right, when everything was tightened up. I measured the amount of play, about 2mm with a feeler gauge. I got a spacer at the LBS, and installed it on the non-drive side, my existing FD did not require adjustment & chain line was good. If your FD/chainline needs to move out to the right, you can add the spacer on that side. If you assemble and you don't have side to side play, forget about it and put it in the spare parts box.


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## frdfandc (Nov 27, 2007)

On the bikes at the LBS I work at with the FSA Gossamer Triple, no spacers are used.

And as was posted up previously, the FSA tech doc does not show any spacers as being required.


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## bon_gabs (Feb 2, 2010)

spacers are needed only if you're using the external BB on the MTB with etype FD..correct if Im wrong,:idea:


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## alexb618 (Aug 24, 2006)

for mountain bikes


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## Camilo (Jun 23, 2007)

OK, I've not used that particular BB or crank, but....

I had to use drive side spacers on a triple crankset I installed on my Felt ZC frame. This was simply a front derailleur/frame issue. The frame interfered with the front derailleur and wouldn't allow it to move inward far enough to drop the chain onto the inner ring. I had to put spacers on the drive side to move the entire driveside outward a couple of mm to make it work... and work it did, just fine. It did mess up the chainline a little bit, but not in a way that caused any noise or shifting problems. Yes I was using the right spindle length. It wasn't a problem with the clearance between the frame and the chainrings or the crankarms, but just the derailleur and the frame. I'd used the same set up had worked fine on a different frame w/o spacers.

When I recently installed a compact double on the frame - different BB and derailleur - no spacers were needed.

Maybe the person who previously owned the crankset had some specific reason for the spacers because of the specific frame/derailleur, or chainring/seat stay clearance he had. You should install it and see if it works w/o the spacers.


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