# Converting cranks from standard double to compact double (Ultegra)



## Gordon Gekko (Jan 24, 2008)

I am planning to convert from a Ultegra 53/39T crank set to a Ultegra SL 50/34T crank set and have a couple of questions. 

1. It looks like the part I need is FC-6650G. Can anyone confirm this? Also, I noticed there was an earlier version numbered FC-6600. Aside from the weight difference (the FC-6650G is 45g lighter), were there any other improvements to FC-6600?
2. Where can I get the best price for this part? Any internet or mail order vendors you would recommend? 
3. Is there anything else I need to purchase or consider with this swap? Since I moving from one Ultegra to another, I assume the conversion is straight forward. 

Thanks. 

*My specs:*
Bike: 2007 Felt F3.
Size: 54 cm (I'm 99% certain this is the size; I'm 5' 10"). 
Cranks: 172.5 mm Ultegra 53/39T (I'm 99% certain this is the length).
Derailleurs: Dura-Ace F/R (2007 vintage)
Shifters: Dura-Ace (2007 vintage)


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## TempestRS4 (Oct 15, 2008)

Can you put smaller chainrings, 50/34 on your current crankset? Would that be cheaper?


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## Gordon Gekko (Jan 24, 2008)

TempestRS4 said:


> Can you put smaller chainrings, 50/34 on your current crankset? Would that be cheaper?


I was told no by my LBS.


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## TempestRS4 (Oct 15, 2008)

Ahh, right, the bolt circle diameter for the compact crank is smaller. 110 vs 130. Sorry


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## android (Nov 20, 2007)

G = SL meaning grey. A 6600 is a silver 130 bcd 53/39 crank. A 6601G is basically the same thing in grey. Shimano usually used xx50 to denote a compact crank and xx03 to be a triple. 00/01 are typically standard cranks.

Yes, 6650G is the compact Ultegra SL crank. It is stock with 50/34 rings on it. 

If your existing crank is 10 speed Ultegra 6600 series, then you just loosen and remove the left side crank arm, pull out the unit from the right side of the bike, then put the new one in just the opposite. 

You should definitely torque the bolts on the left crank arm using a torque wrench.


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## Gordon Gekko (Jan 24, 2008)

android said:


> G = SL meaning grey. A 6600 is a silver 130 bcd 53/39 crank. A 6601G is basically the same thing in grey. Shimano usually used xx50 to denote a compact crank and xx03 to be a triple. 00/01 are typically standard cranks.
> 
> Yes, 6650G is the compact Ultegra SL crank. It is stock with 50/34 rings on it.
> 
> ...


Thanks. This is very helpful. Any recommendations as to where to buy the cranks?


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## Suge206 (Nov 20, 2008)

Ebay!


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## Dajianshan (Jul 15, 2007)

My builder installed an Ultegra 6600 traditional crank on my bike when he built it up although I wanted a compact (traditional was easier to find). He was finally able to find the 105 50/34t set that fit right on. My drivetrain is all Ultegra... except...


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## RoadCube (Nov 22, 2006)

Need to move the FD down to compensate for the smaller 50 ring. I am not sure to the clearance distance with the 50 but that info should be on the web
RC


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## tarwheel2 (Jul 7, 2005)

I am making a similar conversion to my commuter bike. The best prices I found for Shimano compact cranks were at some of the British/Irish web stores like probikekit, chainreactioncycles, wiggle, totalcycling, ribble, sjs. However, they are often out of stock when you find something you want to buy. Shipping can be more expensive, but wiggle and chainreaction offer free shipping if your total order exceeds a certain amount. Probikekit currently has free shipping to the US.

Sometimes you can find comparable or even better prices on eBay. I ended up ordering a Campy Centaur compact crank from eBay, because the British stores were out of stock and I found one on eBay that was within a few dollars.


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