# need help replacing Omega Compact MegaExo crankset



## rasputinlv (Aug 27, 2011)

Hi guys. I just got cannondale caad8 6, which came with Omega Compact MegaExo crankset.
I would like to get crankset with 53/39. I'm new at this and having hard time understanding and finding crankset that would fit to my frame.
Please help if you have any info.
Thanks an advance.


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## omgBikes (Dec 12, 2009)

I apologize if you know some/all of this, but I'm just not sure about the extent of your experience. Your frame is using an "english" bottom bracket - meaning there are threads in the frame, and external cups with bearings are threaded into the frame. The crank, with it's integrated spindle, goes through the cups and frame, and the left crank arm is clamped to the end of the spindle.

If you wouldn't be opposed to getting a new bottom bracket as well, you can use essentially any crank that uses a standard, threaded bottom bracket, so *not* BB30 cranks. You could use any FSA crank with your current bottom bracket cups though, since they are the FSA style (but again, not their BB30 cranks).

I know some people mix and match bottom bracket and crank brands - for instance, using an FSA crank with Shimano bottom bracket cups and vice versa. I don't because I'm too lazy to think about it and make sure it's all OK, but some people have great success. 

On SRAM/Truvativ cranks, the end of the spindle actually tapers to a smaller diameter than other brands, so the non-drive side bearing on their bottom bracket cups has a smaller inner diameter. For this reason, you can't mix SRAM cranks with other brands' bottom brackets or SRAM bottom brackets with other brand's cranks.

So long story short, you should be able to buy any standard FSA crank, or any standard, threaded crank and bottom bracket from another company and be fine. You would need to move the front derailleur up a bit to account for the bigger rings, and maybe get a new chain so it's longer. Hope this helped.


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## rasputinlv (Aug 27, 2011)

Hi.
Thank you veyr much for reply. Actually I'm so new at this, just few days ago I found out what bottom bracket is 
I guess I don't mind getting new BB, looks like most of them come with them. 
Would this feet? :
With MegaExo BB
BB-6000
DESCRIPTION & MATERIALS
• MegaExo oversize cartridge bearings
• MegaExo alloy bearing cups
SIZES
• Ø24mm spindle
• BB Cups - BC-1.37” x 68mm or M36 x 70mm
BB WEIGHT
• 101 g

Its Gossamer Pro MegaExo.
I'm also thinking about upgrading to 10 speed


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## omgBikes (Dec 12, 2009)

Yeah, that would work fine.


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## rasputinlv (Aug 27, 2011)

Great  Thank you very muc.
So these are the numbers are need to look for to feet my frame?: BB Cups - BC-1.37” x 68mm


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## Mr Evil (Aug 12, 2011)

I just did a quick search, and it looks like the FSA Omega has a 19mm spindle instead of the more common 24mm, in which case that bottom bracket won't fit your current crankset.

You don't need a complete new crankset + BB though, you can replace just the chainrings. You will need a pair of 53/39 chainrings with a 110mm BCD (110mm is the standard for compact cranksets, compared to 130mm for normal ones).


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## omgBikes (Dec 12, 2009)

The first number is the diameter of the bottom bracket shell in the frame, and the second is the width of the bottom bracket shell of the frame. 

So yes, they are the correct numbers, and you will just see many manufacturers and websites say "English" bottom bracket, but that's what they mean, and that's what you have.

Like your previous post with the details of the bottom bracket: "• BB Cups - BC-1.37” x 68mm or M36 x 70mm". M36 x 70mm (or 36mm x 70mm) is "Italian" threading. There are very few bikes anymore with that size, but it's still out there.


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## omgBikes (Dec 12, 2009)

Good catch Mr. Evil. I didn't realize that.

And it seems pretty tough to find a 53/39 with a 110 BCD


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## rasputinlv (Aug 27, 2011)

OK, looks like I'm stuck with what I have then 
Thanks guys.


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## Gimme Shoulder (Feb 10, 2004)

You can get 53 and 39 chainrings in 110 bolt circle to fit your current crank. Google TA Chainrings.


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## rasputinlv (Aug 27, 2011)

Wow, found them!
Thank you guys for your help.


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## AndrwSwitch (May 28, 2009)

Can you really spin out 50/11?

Sorry for the "that guy" moment.

If you're set on doing this change, consider a whole new crankset that's already a standard double. Something like the Shimano Tiagra model would be a little nicer than your Omega, have a better bearing (IME. I think the BB-4000 is a POS) and it may not cost you a whole lot more - TA chain rings are not the cheapest. Shimano rings are really nice, IME, even the relatively cheap ones.


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## rasputinlv (Aug 27, 2011)

That's funny you mentioned Tiagra, because rest of my stuff is Tiagra. Bike is cannondale caad 8 6. I'm going to take a look at Tiagra crankset then as well.
Thanks.


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## frdfandc (Nov 27, 2007)

The Omega FSA external BB crank has a smaller spindle than the other external style cranks on the market.

So no matter what you choose to install, you will need to replace the bottom bracket cups.


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## rasputinlv (Aug 27, 2011)

That would be fine. I guess I'm missing what is BB and what is caps.


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## AndrwSwitch (May 28, 2009)

http://techdocs.shimano.com/media/t.../FC/EV-FC-4600-3144_v1_m56577569830753741.pdf


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## Gimme Shoulder (Feb 10, 2004)

Actually, the easiest way to get a more aggressive gearing with what you've got is to simply put a 11-23 cassette in the back. I'm guessing your bike came with a 12-25. If that is the case, then if you were to swap in the 53/39 ringset you propose, your top gear would be 53/12 = 4.417, and your granny would be 39/25 = 1.56. But if you just swapped in a 11-23 cassette with your current 50/34 ringset, your top gear would be 50/11 = 4.545, and your granny would be 34/23 = 1.47. Pretty close comparison. In fact, the granny is even a little lower.


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## rasputinlv (Aug 27, 2011)

Ended up getting whole new bike:SuperSix ultegra and asked shop to put 39/53
problem solved 
Thanks guys.


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