# Specialized Crankset vs. Dura Ace 7900 Crankset



## sjackman (Jun 8, 2008)

i am about to buy a 2011 tarmac pro, and i am trying to decide between ordering the fully built up dura ace model of the bike (with the specialized crankset and OSBB), or ordering just the tarmac pro frameset and building the bike up with a full dura ace 7900 groupset (including the dura ace 7900 crankset). the money looks to be about the same. i ride about 180 miles a week (mostly climbing), i weigh about 190-195 lbs, and my ftp is about 360 watts. i race a little (i'm a men's C collegiate racer), but mostly i just love going for long challenging rides, and want high quality equipment that will last. what do you guys recommend? also, if i get the frameset and buy the dura ace groupset separately, is the tarmac pro frameset bottom bracket threaded for english or italian? should the front derailleur be braze on, 31.8 clamp, or 34.9 clamp? thanks for your input.


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## ukbloke (Sep 1, 2007)

sjackman said:


> i am about to buy a 2011 tarmac pro, and i am trying to decide between ordering the fully built up dura ace model of the bike (with the specialized crankset and OSBB), or ordering just the tarmac pro frameset and building the bike up with a full dura ace 7900 groupset (including the dura ace 7900 crankset).


The Dura Ace 7900 crank-set is very nice, and IMHO one of the best choices out there. You could also go with the 7950 compact if that's more appropriate for your hill climbing. You would want an English BB and braze-on FD. The Specialized crank-set and OSBB saves some weight, and looks quite nice, but doesn't have the same reputation as the Dura Ace. I wonder if there might be some other component of the build that would sway your decision - eg. wheelset, would you pick something other than the Roval Fusee SL given the choice? Also if you look at the specs, the Pro DA bike only has 3 Dura Ace components (shifters, FD and RD) hardly a group-set. Note that the Pro frame-set is only available in white, while the Pro bike is mostly black which might influence your decision.


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## sjackman (Jun 8, 2008)

thanks for the feedback. i was indeed intending to get the 7950 compact crank from shimano, not the standard size. i would also be getting the compact (50/43t) specialized crankset swapped in if i went that route. i had noticed that the dura ace bike comes with ultegra brakes, cassette, and chain, and was factoring in the cost of upgrading those (swapping them out through my LBS) when i said the cost was about the same between the two bikes. i was also assuming that i was going to sell the wheels the bike comes with for $400-$500, as i already have a wheelset that's much better suited to a rider my size (dt swiss 240s front hub, powertap sl+ rear hub, dt swiss rr585 rims, 28/32 sapim cx-ray spokes). in fact, i have a hunch that the dura ace rig (with 7950 crank) might come in cheaper overall (though prices are very sketchy at the moment, i'm still getting them confirmed at my LBS). also, according to the specialized website and my LBS, the frameset is available in either the white/red or the black/blue option. but, am i right in reading that it sounds like you'd recommend the dura ace crank over the specialized crank?


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## PJ352 (Dec 5, 2007)

JMO, and I have no firsthand experience with either the current DA or Spec BB30 cranksets, but I'd definitely go with the the Pro frameset w/ standard BB and build from there. Between Specs BB30 and their CF cranksets there have just been too many issues. Shimano's cranksets/ BB's may be a little less bling, but they're near bullet proof, IME.


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## DAG on a bike (Jun 19, 2010)

PJ352 said:


> ...Specs BB30 and their CF cranksets there have just been too many issues...


too many issues? What exactly?

I've been using my CF compact for 18 months now and never had the slightest hint of a problem.


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## PJ352 (Dec 5, 2007)

DAG on a bike said:


> too many issues? What exactly?
> 
> I've been using my CF compact for 18 months now and never had the slightest hint of a problem.


It's well documented that the earlier Spec cranksets (chainrings) were trouble prone and it took more than a couple of design changes (and years) to correct the issues. Same with the current BB30's. Seek (here on RBR and elsewhere) and you shall find (the specifics). I did.


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## ewitz (Sep 11, 2002)

I find it hard to believe that this is even a decision.

The nicest part of the whole 79XX series of componentry is the crankset. The ramping and pinning is to a large part what makes the front shifting so quick. And you are giving that up for the potential to save a few grams?


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## Scott in MD (Jun 24, 2008)

I have a 2008 Tarmac with an Ultegra crank and a 2009 Cannondale Slice tri race bike with a BB30 OEM crank ... actually a SRAM Force labled Cannondale .... and I love the BB30. My next Tarmac will absolutely be a BB30 crank. I like Shimano ... but I'd buy the frame and install a DA crank when BB30 configuration comes out. No question. I've ridden both and it's not even a question for me.

And it's not a couple of grams lighter ... it's a couple of ounces.


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## Dr_John (Oct 11, 2005)

> I'd buy the frame and install a DA crank when BB30 configuration comes out.


Maybe I'm misunderstanding this statement. I've never seen any mention of Shimano planning to release BB30 cranks. And a threaded BB with BB30 adapters pretty much defeats the purpose of BB30.


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## Scott in MD (Jun 24, 2008)

I haven't either .. I am just assuming they will before too long. Press-fit bearings make so much sense, and I think Shimano has to serve this application at some point. (You can also get the press-fit adapters that accomodate DA-style external threaded bearings, but this kills the lighter weight benefits of BB30 and at least Cannondale says "don't take them out once you put them in a carbon frame" but there is a tool to remove the adapters ... my LBS has removed the BB30-to-integrated adapters sucessfully).


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## PJ352 (Dec 5, 2007)

Scott in MD said:


> I haven't either .. I am just assuming they will before too long. Press-fit bearings make so much sense, and I think Shimano has to serve this application at some point. (*You can also get the press-fit adapters that accomodate DA-style external threaded bearings, but this kills the lighter weight benefits of BB30 and at least Cannondale says "don't take them out once you put them in a carbon frame" but there is a tool to remove the adapters ... my LBS has removed the BB30-to-integrated adapters sucessfully)*.


I think you're confusing things. There is one type of BB30 adapter that allows the use of standard threaded BB's that C'dale recommends not removing once installed:
http://www.universalcycles.com/shopping/product_details.php?id=29424
The third bullet says it all.

There is another type (shims) that do essentally the same (but integrate the BB bearings) and can later be removed for BB30 use:
http://www.bikeman.com/CR1243.html?...utm_medium=GoogleBase&utm_campaign=GoogleBase

If your LBS removed the first type, they'd likely void the manufacturers warranty.


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## crumjack (Sep 11, 2005)

Forum contributor "Starnut" says the adapter is removable by any decent mechanic without issue.

Other solutions such as the Rotor adaper you can hear about in the Interbike video to the right sounds like a simpler solution much less susceptible to creaking than a loctited adapter.

Yep, speshy had some chainring issues years ago as did SRAM. Improvements have apparently been made. If you get the spesh crank and don't care for the rings, you can always pick up SRAM, TA, Rotor or whatever else you like...


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## PJ352 (Dec 5, 2007)

crumjack said:


> Forum contributor "Starnut" says the adapter is removable by any decent mechanic without issue.
> 
> Other solutions such as the Rotor adaper you can hear about in the Interbike video to the right sounds like a simpler solution much less susceptible to creaking than a loctited adapter.
> 
> Yep, speshy had some chainring issues years ago as did SRAM. Improvements have apparently been made. If you get the spesh crank and don't care for the rings, you can always pick up SRAM, TA, Rotor or whatever else you like...


No offense meant to the forum contributor, but while he can offer an opinion and post experiences, in the event of a problem he doesn't dictate a manufacturer's warranty policies, so I doubt the mention of 'Starnut' is going to result in getting a claim processed.

I agree that Rotor's BB30 adapter is (in theory) a superior alternative to the others, but I'm not so sure about those oval chainrings.


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## Dr_John (Oct 11, 2005)

> I am just assuming they will before too long. Press-fit bearings make so much sense, and I think Shimano has to serve this application at some point.


You're more optimistic than I am. BB30 has been out for quite some time, and I haven't seen a single mention of Shimano considering adopting it. Hope I'm wrong, but it reminds me of the no compact 7800 Dura Ace crank. I don't buy the "Dura Ace is for pros, and pros don't use compacts" since they made a 7800-series triple. It just wasn't in the plan/design for that series.


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## crumjack (Sep 11, 2005)

PJ352 said:


> No offense meant to the forum contributor, but while he can offer an opinion and post experiences, in the event of a problem he doesn't dictate a manufacturer's warranty policies, so I doubt the mention of 'Starnut' is going to result in getting a claim processed.
> 
> I agree that Rotor's BB30 adapter is (in theory) a superior alternative to the others, but I'm not so sure about those oval chainrings.


One thing I should have mentioned is he is a CDale dealer and has actually dealt with these issues which is why I mentioned him. Certainly if there are concerns regarding warranties I recommend checking with your local dealer and/or product rep before proceeding. 

To answer the original question, you can't go wrong either way. In my mind, a DA build deserves a DA crank whereas SRAM leaves me more open to mix and match. Go with what your gut says and not what some random internet voices (including mine) are saying.


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## RkFast (Dec 11, 2004)

If I could bump this up, Im also considering a Tarmac SL3 and want DA7900 across the board. So I would order the frameset with the threaded, english BB. 

Question is....is this really taking away from the frame's stiffness or longevity in any way? If I maqy use a NASCAR analogy, by going with a threaded, non BB30 BB am I putting a "restrictor plate" on the bike?

I understand that BB30 is lighter and the claim is that its a stiffer setup as well. But DA cranks with a standard BB are featherweight and really, really stiff in their own right. Plus lets be honest, either way I build this bike (BB30 or non), its going to be ~15lbs and really lightweight. 

Again, my concern is the frame....by leaving BB30 out am I leaving out any of the frame's good attibutes? Outside of any benefit the cranks, themsevles might provide does a threaded BB Tarmac FRAME "ride different", is different in stiffness or ANY other attributes than a BB30 one?


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## PJ352 (Dec 5, 2007)

I'm of the mind that BB30 (and similar) is a mix of marketing hype and a step towards future modular/ proprietary frame designs, so taking my biases into account, I think there is zero difference in the Tarmac with and without OS BB's. 

To verify this, you could submit a question to customer service (their response time is excellent, IME) - I'm predicting they back up my claims. And in the absence of any controlled study on this topic, Spec's feedback is likely the most reliable you'll find.


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## RkFast (Dec 11, 2004)

So I did and Spesh says get the BB30 and convert it to threaded, as they feel all manufacturers will be going to a BB30 (or similar) setup in the future.


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## PJ352 (Dec 5, 2007)

RkFast said:


> So I did and Spesh says get the BB30 and convert it to threaded, as they feel all manufacturers will be going to a BB30 (or similar) setup in the future.


I'm sure that option would work out fine for you, but I'm equally sure that you'll likely be riding your next frame by the time BB30's (or similar) become the standard - or maybe more accurately, threaded BB's will become obsolete. 

I'll temper that with the fact that Shimano is now marketing 'BB30 type' (I think they call them BB86?) adapters, so that IMO lends some credibility that the conversion might actually happen.

EDIT: It's actually called Shimano's press fit system.
http://www.parktool.com/repair/readcalvinscorner.asp?id=231

http://techdocs.shimano.com/media/t...001/SI_0053A_001_En_v1_m56577569830625426.pdf


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## ukbloke (Sep 1, 2007)

PJ352 said:


> I'll temper that with the fact that Shimano is now marketing 'BB30 type' (I think they call them BB86?) adapters, so that IMO lends some credibility that the conversion might actually happen.


The interesting thing about the Shimano press-fit system is that it works with the existing Shimano cranks. It should have similar weight/simplicity/performance advantages of BB30 (though I don't consider them a big deal). One can argue whether it has the same stiffness given that it keeps the existing Shimano crank spindle diameter (~24mm?) rather than the BB30's 30mm. Crank spindle stiffness has never been a big concern of mine!

Of course, you'll need a new compatible frame to go along with Shimano's press-fit system. Not clear what frame that was on the Park Tool site - some generic Taiwanese carbon frame? And this almost certainly means that Shimano will not do BB30 compatible cranks. I guess Shimano will release this as an alternative BB when they have some bike manufacturers lined up. It is very easy for Shimano - they are basically just selling a new BB bearing - but not really a whole lot of money in it for them. I suspect that this is coming more from manufacturers wanting to sell new frames, and Shimano filling that need to avoid further erosion of market share to SRAM.


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## ukbloke (Sep 1, 2007)

The Shimano system is indeed typically called BB86 and is found in higher end Scott and Giant bikes. There's a good listing of all the new BB "standards" here.

The way I see it is that if you are going to use a Specialized frameset with SRAM (or Specialized's or FSA's crank) get the OSBB, but if you are going to use Shimano get the regular BB. If you honestly think that in the future you will want to swap crank-set then get OSBB and use an adapter. If you are planning to run Shimano it doesn't really make sense to me to get the OSBB and the adapter in the hope that they bring out a BB30 crank-set - all indications are that they will not.


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## PJ352 (Dec 5, 2007)

ukbloke said:


> *The interesting thing about the Shimano press-fit system is that it works with the existing Shimano cranks.* It should have similar weight/simplicity/performance advantages of BB30 (though I don't consider them a big deal). One can argue whether it has the same stiffness given that it keeps the existing Shimano crank spindle diameter (~24mm?) rather than the BB30's 30mm. Crank spindle stiffness has never been a big concern of mine!
> 
> Of course, you'll need a new compatible frame to go along with Shimano's press-fit system. *Not clear what frame that was on the Park Tool site - some generic Taiwanese carbon frame?* And this almost certainly means that Shimano will not do BB30 compatible cranks. I guess Shimano will release this as an alternative BB when they have some bike manufacturers lined up. It is very easy for Shimano - they are basically just selling a new BB bearing - but not really a whole lot of money in it for them. I suspect that this is coming more from manufacturers wanting to sell new frames, and Shimano filling that need to avoid further erosion of market share to SRAM.


Yes, Shimano's press fit system can be viewed more as an alternative to their Hollowtech ll BB's to be used in OS BB's, so (my) saying that it lends itself to the conversion (to BB30) isn't really accurate. More, it's a mechanism allowing the use of Shimano's cranksets in OS BB's.

There may be others, but Fuji lists Shimano's system in some of their 2011 bike specs:
http://www.fujibikes.com/bike/details/altamira_3_0


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## grn (Sep 17, 2010)

*specialized cranks*

I have now cracked a lockring on my Specialized cranks 3 times in less than three years, resulting in a squeaky creaking crank. Combine this with the two other sets of Roval wheels that have cracked in 2 years and the Specialized tires that last about 1000 miles and you have a company that does not build durable equipment. I have also broken 3 buckles on Specialized shoes and the replacements are impossible to find. They should keep concentrating on their frames and give up the rest of the stuff that is generally overpriced crap; including the very flexy S-Works chainrings. Buy the Shimano, you cannot go wrong with Shimano performance, reliability and value.


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## jnbrown (Dec 9, 2009)

I am pondering the same question. I am really drawn to the S-Works cranks mainly due to their looks and theoretically they save almost 200g of weight over my Ultegra 6700 cranks.
Not sure if it would make much differnce in stiffness though although its a possibilty.
It seems that the S-Works frameset and cranks just go together and its what Contador, Schleck and Cancallera have been riding.


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## Ronman (Feb 12, 2007)

I read some Shimano literature many months ago on their 7900 gruppo, which of course highlighted the 'new and improved'. I was interested in why they still do not have a BB30 offering, and in that literature they explained, however briefly, why they stayed with the 24mm spindle. According to their literature, they found the 24mm spindle to be the best design when comparing the stiffness of 24mm vs 30mm, and increased rotational resistance of the 30mm vs 24mm (I can't remember the exact technical jargon used). I read this to mean the 24mm spindle delivers the necessary stiffness without the increased rotational resistance (surface friction) of the 30mm spindle. 

An interesting sideline to this (to me anyway) is the on-going development in F1 and motorcycle engine design, i.e., high rpm engines, where engineers are constantly experimenting with crank journal diameter. They like larger diameter journals for stiffness, but the frictional losses of the greater surface area eats up valuable power and generates unwanted heat. The outcome is a compromise providing acceptable stiffness and friction losses. 

Obviously we are talking major differences in rpm between a bicycle crank and F1/motorcyle engine, but the point is not without merit it seems.


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## RkFast (Dec 11, 2004)

"Flexy chainrings"?

Eh?


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