Another Defy question - crankset upgrade?

[glambx]

Everyone here has been so helpful! I have one last question.

According to the specs sheet I've got an FSA crankset + bearing:

Gossamer MegaExo 30/39/50
SA Gossamer, Internal Press Fit

The bearing seems pretty lousy with a lot of friction. The shifting is lousy, and I don't need a triple chainring (I thought I was receiving a compact).

I'd like to upgrade to an Ultegra 50/34.

What am I getting myself into?

Do I need to order any adapters, or a new bottom bracket?

I was planning to order this:

Shimano Ultegra FC-6750 Compact Crankset - Components Sale

Is that all I need?

 

[alfeng]

According to the specs sheet I've got an FSA crankset + bearing:

Gossamer MegaExo 30/39/50
SA Gossamer, Internal Press Fit

The bearing seems pretty lousy with a lot of friction. The shifting is lousy, and I don't need a triple chainring (I thought I was receiving a compact).

I'd like to upgrade to an Ultegra 50/34.

What am I getting myself into?

Do I need to order any adapters, or a new bottom bracket?

I was planning to order this:

Shimano Ultegra FC-6750 Compact Crankset - Components Sale

Is that all I need?

In theory, you don't need to order a new BB since FSA MegaExo & Shimano Hollowtech II can use the same external BB.

I have both FSA MegaExo & Shimano Hollotech II cranks ... I don't think the FSA BBs are "lousy with a lot of friction" ... so, there may be either a maintenance issue or something else may be amiss with your BB.
​

Because you feel that your BB is tight, you may as well replace the cups/bearings with a set of Hollowtech II BB cups since they aren't very expensive.

The same BB TOOL is used to remove/install either a MegaExo or a Hollowtech II BB.

It could simply be that whoever installed the crank over-tightened the adjusting bolt ... try loosening the two bolts that secure the non-driveside crankarm ... back the large adjusting bolt out of the BB spindle ... turn the crank through a couple of rotations ... put the adjusting bolt back in place ... tighten the two bolts on the crankarm.
​

BTW. GREASE IS YOUR BIKE'S FRIEND!

Now, as far as the shifting, while the 6750 crankset would be a sweet addition to almost any bike, it may only marginally improve your shifting ... and, you will probably weep when the time comes to replace those chainrings.

IMO, there are two things you could do to improve your shifting ... the first is to change the derailleur cables & housing ... AND, when you do, you must give serious consideration to lightly lubing them even if they are either Shimano OR Campagnolo cables & housing.

With Shimano shifters, I found that using standard, COILED Brake Cable housing works well ... maybe, better. OTHERS have disagreed on this point ... and, maybe they are right.

The OTHER thing which will more drastically improve your shifting would be to change to Campagnolo shifters ...

Yes, I know your bike has a Shimano drivetrain ...

The attached pic is one of my bikes which happens to have a "Compact" FSA MegaExo crank + Campagnolo 10-speed shifters + XTR rear derailleur + a really vintage (c1979) Shimano Dura Ace front derailleur. The front derailleur works great, and other than requiring an extra click (4-clicks, total ... which may be the prior norm for Campagnolo front derailleurs -- who can remember?) than with with my preferred Shimano front derailleur (6500/6503) which uses 3-clicks between the inner & outer chainring.

You can readily find a set of new, 10-speed (non-QS, non-PowerTorque) Campagnolo shifters for less than $200 +/- ... a more mundane "Compact" crank (either FSA or Shimano) certainly doesn't have to cost more than $100. Add about $35 for some new Hollowtech II BB cups. If you are a wise shopper on eBay, then you can probably get all of it (less the BB tool) for under $200.

 

[glambx]

Thanks alfeng.

I'll take off the left crank arm like you suggested and check to make sure it's not just too tight.

Now they you mention it, I'd be surprised if that wasn't the problem, because I can't imagine it's supposed to come this way.

So, in theory I could just pull the bearings, spindle and crank arms, and replace them straight up with the Ultegra's?

 

[alfeng]

So, in theory I could just pull the bearings, spindle and crank arms, and replace them straight up with the Ultegra's?

The way the external BBs are designed the bearings are (except on Campagnolo cranks) in the cups ... and then, a plastic seal covers the bearing ... it is designed as a low-maintenance assembly which user never has to open ...

You could theoretically tap the existing bearings OUT and press new bearings IN, and then put the plastic seal back in place ... but, I suspect your LBS would charge as much for a pair of bearings as a new BB might cost.

Anyway, presuming the FSA BB which is in your bike is 'okay', then you would just remove the old crank (you may need to tap it out with a RUBBER mallet ... or, place a block of WOOD on the end of the spindle & lightly tap the block of wood), slide the new crank in place, put the non-driveside arm on the spindle so that the arm is 180º opposite the driveside arm, put the large (Shimano's is plastic) adjusting bolt in place ... tighten, but not too tight ... then, tighten the pinch bolts.

A light grease on all of the metal-to-metal contact surfaces is generally a good idea.
​

BEFORE you put the non-driveside arm on, the crank should spin smoothly (presuming the chain is not in place) ... if it doesn't, then there may indeed be a problem with the bearings OR (less likely, but always possible) the BB shell may actually need to be faced (this should have been done before the initial assembly) ...

I found that NONE of my frames needed to be faced ... at least ONE person declares that the BB shell always needs to be faced.

 

[alienator]

So, in theory I could just pull the bearings, spindle and crank arms, and replace them straight up with the Ultegra's?

Yup. It's a simple switch.

 

[glambx]

Excellent.. that's what I was hoping for!

 

[Peter@vecchios]

Thanks alfeng.

I'll take off the left crank arm like you suggested and check to make sure it's not just too tight.

Now they you mention it, I'd be surprised if that wasn't the problem, because I can't imagine it's supposed to come this way.

So, in theory I could just pull the bearings, spindle and crank arms, and replace them straight up with the Ultegra's?

Yes and make sure the frame is prepped. I see hundreds of frames every year and most need to be prepped, faced and chased. Not just a couple of my own but customer's frames. sigh....

 

[glambx]

Yes and make sure the frame is prepped. I see hundreds of frames every year and most need to be prepped, faced and chased. Not just a couple of my own but customer's frames. sigh....

This.. sounds important.

What do you mean exactly?

 

[Peter@vecchios]

This.. sounds important.

What do you mean exactly?

Being in a service oriented bike shop I see many frames per year..new and old, and most need to have the BB and headtube 'machined' a wee bit to ensure the 'faces' of the BB shell and headtube are parallel. Making them parallel will ensure the bearings in the HS and BB are not canted at all and will make for long life and smooth operation. Essential for 'metal' bikes, not really possible with carbon frames altho these seldom have BB 'faces' that are parallel. BUT taking a tool to the shell can compromise the way the metal BB shell is attached(glued) to the BB shell causing early failure.