# S-works crankset with 7900 group?



## P.D.E. (Oct 15, 2006)

Anybody using the S-works crankset with 7900?

I'm building up a 09 Tarmac SL2 frameset (BB30) and deciding on which crank to use: S-works or 7900 (with adapter)...the rest of the groupset will be 7900. Wondering how the shift quality and stiffness stacks up against the 7900 crank.


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## Pokey (Apr 15, 2006)

THat's a tough one.

I have an 09 Roubaix SL pro DA.

- Specialized Carbon crankset with OS BB (BB30)
- DA 7900 shifters
- DA 7900 chain
- DA 7900 Front Derailleur

I am less than impressed with (1) the spacing on the Specialized chainrings (Chainline) on their carbon BB30 crankset and (2) the pins/rivets for chain pickup on the large chainring. 

With the position of the chainrings from the factory, they are not spaced correctly which makes proper front derailleur setup almost impossible. With no slack in the der. cable and in the small chainring position, and the Low limiter set in the right spot, When you shift into the large chainring, when the Derailleur clicks into the high gear, there is too much travel on the der (Or more likely the large chainring is too close to the small chainring) so the derailleur almost pushes the chain completely over and off the large chainring. So then you set the high limiter screw to keep from letting the derailleur over-shift but when you do, you never reach the SIS engagement click to lock it in the top position without way too much pressure on the lever.

So the fix for me was to leave some slack in the derailleur cable in the low gear position against the limiter. But this requires an excessive amount of stroke on the front (left) shifter which I can barely make with my smaller hands. But at least I don't have to worry about dropping the chain inside or outside or needing excessive force to get the FD locked in the large chainring position. Once in the proper gear, the cranks are great, but they don't shift well with the 7900.

It's really quite annoying.

Also, there are still 3 positions in the 7900 integrated shift lever for the FD even though they claim they have eliminated the trim settings. There is a trim setting for the small chainring, but not for the large. But with the large movement of the trim setting click and then the large chainring click, there's too much stroke for the specialized chainring spacing. It almost seems as though I have a tripple 7900 FD, but there is no such thing.


The pins on the inside of the large chainring are just flat rivets - no shape to them at all. Seems like they are about 8-9 years behind in technology there from shimano there - they even lag FSA in pin technology. my 2006 FSA chainrings have mre appropriately shaped pins.

Another word of advice - use a 7900 chain, but make CERTAIN you don't put it on inside-out. One side is now different than the other. My LBS put mine on inside-out and I had mad chain such in front from the Large to small chainring. After reading the manual, I realized the chain was on backwards, removed and installed it correctly, and now zero chain suck.

Good luck.

Any idea what that shimano adapter looks like? I am curious to see what it would take to change to a DA crankset.

The Specialized cranks are nice and stiff and seem to be well-made. Too bad the spacing seems way off.

Maybe the LBS messed something else up too though.


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## cyclequip (Oct 20, 2004)

The design of the new DA makes clean shifting with S-Works cranks very difficult. The new DA cranks are SOTA when used with the rest of the 7900 gruppo and provide by some measure the best front gear shifting around.
The adaptor is basically a threaded barrel that fits inside the BB30 shell and uses an Italian thread BB to screw in (and can be properly tightened with the counter-threaded bearing inserts). Included in the adaptor kit are 2 large washers to face up to the BB shell.


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## Pokey (Apr 15, 2006)

cyclequip said:


> The design of the new DA makes clean shifting with S-Works cranks very difficult. The new DA cranks are SOTA when used with the rest of the 7900 gruppo and provide by some measure the best front gear shifting around.
> The adaptor is basically a threaded barrel that fits inside the BB30 shell and uses an Italian thread BB to screw in (and can be properly tightened with the counter-threaded bearing inserts). Included in the adaptor kit are 2 large washers to face up to the BB shell.


Sounds like you have played with this combo a bit. Any idea if using different chainrings would improve the specialized carbon cranks? I don't have the s-works cranks, but they look identical. My LBS suggested I swap the chainrings for the non-series Shimano R700 chainrings. I am not sure if that will help. The R700 rings were not designed around the new 7900 series chain which is very specificly shaped. Also the ramps and pins are only part of the story. I am concerned about chainline and chainring spacing being an issue as well.

Any idea if the adapter (BB30 to External) changes the q-factor at all? I like the way the specialized crankarms and BB feel and fit. I have been contemplating getting a 7900 crankset, but not sure how that will change the fit and feel. No doubt shifting will improve.

Thanks...


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## P.D.E. (Oct 15, 2006)

Thanks for the replies so far...

I also asked Specialized customer service about this today. Unfortunately I didn't get a clear black-and-white answer that S-works will work equally good as 7900 cranks w/7900. But they did say the current rings have been improved and shift better than previous generations.

@Pokey: They also said the ring spacing is the same as 7900. (Also note the rings are different on the Pro level cranks vs S-works...but they didn't say if one or the other is better w/7900)

In my case, I'm still not sure what to do. The 7900 crank is definitely more money and weight and (for people with OS BB's) will require an adapter, however it seems like it probably gives better shifting.


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## Pokey (Apr 15, 2006)

The only difference I can tell is the ni-boron coating. Not sure if the ramps and pins are any different, but then they don't show the back side of the chainrings (the business side ;-)

I am almost wishing I got the s-works Roubaix so I'd have a complete 7900 drivetrain.

I was wondering why, it the specialized cranks are so good, the S-Works comes with DA crankset. Improved shifting is probably why (And 7900 is all the hype right now). But they probably know that their chainrings don't shift as well as 7900 and someone spending that much $$ would not settle for anything but the best shifting.

Let us know what you decide and what you think about the performance of whichever decision you make...


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## P.D.E. (Oct 15, 2006)

Did some more research...looks like there might be another alternative here. FSA says they just came out with 7900 compatible chainrings in the last few weeks, not sure if it's even on the website yet. They also confirmed the ring spacing on 7900 crank is the same as any other crank like K-force etc. Available in black or red/white for about $53 (39T) and $85 (53T). It's not "identical" to 7900 as apparently there are some patent issues but they said initial feedback has been "very good." Interesting... if it looks good on the Spec crank and shifts as well as they advertise this might be the ticket.


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## cyclequip (Oct 20, 2004)

Steer clear of the FSA. The design of the DA 7900 rings is chain-specific - hence the off-set chain and the fantastic front gear performance. Specialized don't yet have the rings/spacing/ramp pins in production just yet. Either go full 7900 including cranks or use the S-Works crankset with 7800. Frankly the legs will need to do the talking anyway.


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## P.D.E. (Oct 15, 2006)

cyclequip said:


> Steer clear of the FSA. The design of the DA 7900 rings is chain-specific - hence the off-set chain and the fantastic front gear performance. Specialized don't yet have the rings/spacing/ramp pins in production just yet. Either go full 7900 including cranks or use the S-Works crankset with 7800. Frankly the legs will need to do the talking anyway.


You haven't convinced me (yet) not to give the new FSA rings the benefit of the doubt. FSA says they are designed to work well with 7900 and Barloworld has been using 7900 with FSA rings all year.


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## cyclequip (Oct 20, 2004)

P.D.E. said:


> You haven't convinced me (yet) not to give the new FSA rings the benefit of the doubt. FSA says they are designed to work well with 7900 and Barloworld has been using 7900 with FSA rings all year.


Absolutely no need to convince you....... You make your bed, you lie in it. 

In which case I'll not tell you what Chris Froome (the rider in the pic) had to say about that Bianchi after he rode a mate's Speshie.


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