Motorad

So, if the Dura Ace 7803 triple gruppo has the better rating and shifting design ... but you wanted a 50x39x30T crankset ... can you buy the Dura Ace 7803 triple gruppo but substitute its 52x39x30T crankset (FC-7803) for the Shimano 105's 50x39x30T crankset (FC-5603)?

If you can make such a purchase ... would the shifting quality of the DA triple gruppo still be the same when using the Shimano 105's crankset (with 50T large ring)?

Is such a replacement of the crankset commonly done, when buying a DA triple gruppo?

mtnbk3000

why not just change out the chainrings

grolby

1. Please don't call a Shimano group a "gruppo." It's an Italian word that is pretentious at best, even when referring to an Italian group. On a Japanese product, it's just plain silly. It's a group! What's wrong wit the English word?

2. There's no problem with this (although downgrading the crankset is unusual, to say the least), but I would re-check the specs on that 105 crankset. There is not a road triple in the world (and especially not a Shimano 105 road triple) with stock 50-39-30 rings. That top ring is definitely a 52. As such, I don't see much point in this change. If you want a 50T top, why not go for a compact crankset?

Motorad

How about calling it a gluppo, using Japanese phoenetics? Following are the specs from Shimano's 105-page:
* Rear Speeds 10
* Chainring Combination 50-39-30T
* PCD 130mm/74mm
* Splined Crank Yes
* Crank Arm Length 165/170/172.5/175mm
* Chain Supper Narrow HG for 10-speed
* Bottom Bracket Included
* Chain Line:45mm

I am not clear whether you can just convert a DA 7803 triple crankset ... by replacing the 52T-ring with a 50T-ring. I was assuming the thickness and diameter of the DA chainrings was very specific for the DA chain and DA rear derailleur. I was assuming the best method to assure smooth DA-shifting was to replace an original crankset (52x39x30T) with an original crankset (50x39x30T). Is my thinking off base here?

What would be best, to maintain the smoothest shifting: replace FC-7803 triple crankset with FC-5603 triple crankset ... or ... get FC-7803 triple crankset and replace 52T chainring with a 50T chainring?

Sheldon Brown

You can. However, that's not what I would recommend.

I'm sure Shimano would like for you to assume that, but it's false. Chainrings have nothing to do with rear derailers, and there's nothing weird about the Dura-Ace big ring. It's the middle and small rings that are oddball, and that's the reason I always strongly advise against buying Dura-Ace triple cranks.

You would be much better off with Ultegra or 105 which use standard chainrings at all three positions.

If you want 50-39-30, 105 would be your best option, because that is a standard set with them.

This would likely result in infinitesimally better shifting from the 39 to the 50 than if you replaced a 52 with a 50 on a standard 52-39-30 set.

The former would be a teeeeeeeensy bit better, and you would have a much more versatile set, where you would have the option of replacing the 30 with something more useful at a later date, if you decide that you would like to have some serious low gears.

"Smoothness of shifting" is really a non-issue in this instance, either of these would work just dandy...but Dura-Ace is for wealthy suckers.

Sheldon "105" Brown

BluesDawg

Aside from Sheldon's good reasons, if you get the 105 crank, you will no longer be tempted to call your mixed bag of components a gruppo or group or grouper or groupetto or whatever. Besides, aren't you already planning to deviate from the full group with your choice of brakes, brake levers and shifters?

well biked

That's a great post, Sheldon. Thorough and concise.

solveg

Thank you for the "gruppo" lowdown.

I have been trying to use the stupid word for 3 months now, thinking it was the correct bike jargon. I don't even own* any Italian components and I could never remember how to spell the stupid word.

Motorad

Thanks for very good input, and maybe I should call my collection the Shimano Bag-O-Stuff?

Another thing I'm confused on ... while keeping with the OP. As far as I can tell, you can not buy Shimano stuff directly from Shimano. But on my last adventure of buying a Shimano gruppo ... er ... Bag-O-Stuff ... it seems the vendors only sold their components as a full complement of specific groupings (DA, Ultegra, 105) ... at least to keep cost down.

I'm pretty sold on the 50x39x30T (you got me thinking BluesDawg), which should keep me in the middle four cogs for the gear inches I use, and should allow me (51 yrs old, 63" ht) use of the big ring at least half the time. So, Sheldon has sold me on the 105 triple crankset. With that in mind: With the 105-triple crank, what would result in a better drivetrain:
* DA-7803 components powered by a 105-5603 crankset. I'd spend the extra bucks if this is better.
* Shimano 105-5603 components which includes a 105-5603 crankset.

BluesDawg

You can most definitely buy Shimano components individually. You can also buy component groups, usually for a discount from the price of the individual components. Usually you can make a certain number of deletions or substitutions from the full group. Ask your LBS about it or look around online.

DMF 

There are definite differences in the thicknesses of the chain rings of each Shimano group. You can't (or shouldn't) mix chain rings between groups. If you want a triple group, it makes more sense to me to buy a 105 or Ultegra group than Dura-Ace. Probably 105 since the shifters are double-triple compatible.

Replacing a 52 with a 50 ring makes no sense at all.

Deanster04

Nothing wrong in using the word "Gruppo" to discribe the set of components. Simply means the same as group. I am sure the japanese aren't insulted. After all we ARE a world economy as the president says.
I had the same issues with campy going to a 30/40/50 chainring setup. I happen to just buy a set of chain rings. If I were to do it again I would go for the Veloce crankset as it would be less expensive and work as well.

Al1943

It probably makes more sense to buy the 105 group and then upgrade individual components as the wear out. The front triple derailleur designs are not the same. You'll have better luck choosing the FD in the same group as the crankset.
Yes, the 10-speed 105 triple comes from the factory with 50-39-30 chainrings, not a bad idea.
And BTW the 10-speed D-A triple comes with 53-39-30 chainrings, the Ultegra has 52-39-30 chainrings.
The front derailleurs are designed for those particular rings.

Al

grolby

The linguistics joke isn't funny. Otherwise, whups! I stand corrected. I fell victim to "It ain't in my dealer catalog, so it don't exist" syndrome. Who knows, it might even be in stock at QBP! Anyway, I agree with Sheldon. For what you want, DA = waste of money.

grolby

There's nothing wrong with it, at least not morally, but it's merely the Italian word for "group." It is neither a technical term nor a brand or trade name. Given that English has a perfectly serviceable word that also means "group," (that word being "group"), using "gruppo" to describe any set of components when speaking in English is a silly affectation at best. It's less absurd when referring to an Italian group, but it's still pretty gosh darn silly. It would make just as much sense to refer to a Shimano group with the Japanese word for group - i.e. none.

That's just plain silly. They're all 10-speed groups. Everything is to the same 10-speed spec. Shimano has zero incentive (and lots of disincentives) to build the groups to different standards. Even if it did, the kind of variations in thicknesses necessary to cause a problem are bigger than you think. Your 10-speed chain would sit just fine on a plain old Sugino chainring from 1986. Mix and match Shimano 10-speed rings to your heart's content, no problem will come of it.

As for the 50 instead of a 52, it's not unreasonable. Let it be, eh?

operator

So I was going to buy a gruppo the other day but then WHAMO, I tried to search the forums but nothing came up for the search term "gruppo". So I went to my local LBS and asked them for a shimano gruppo. They said they did not have any gruppos in stock. So I said got any Campy gruppos? No? What the heck? What kind of a bike store doesn't carry ANY gruppos at all?

So I left the store dejected that I didn't get a chance to even see a gruppo let alone purchase one. Man, I was really itching to put one of those gruppos on my bike. I also didn't get to take a look at the spec sheet for the weight of aformentioned gruppos. Maybe it would've been a heavy gruppo. Who knows. Gruppos 4tw!

Also can anyone recommend a good place to purchase some gruppos? I looked at probikekit but some of their gruppos weren't very inspiring.

DMF 

A word of advice: Have a clue (and do some thinking) before engaging mouth. Read.

Care for a little habaņero sauce with that crow?

DMF 

And if it doesn't?

DMF 

Works for me.

Not only does the DA triple have different thickness rings, it uses a unique(?) 'D' ramp-and-pin arrangement. No, you cannot "just replace the ring".

Your thinking strayed off base with your original assumption that DA is notably better than e.g. 105.

Rutnick

Sheldon,

What's "oddball" about the Dura Ace inner and middle rings? When I ran Dura Ace double, I replaced the inner ring with an Ultegra.

Not sure why a 50 outer ring vs 52...barely any change.

With this logic...just get a R700 and have nearly the best of both.

DMF 

The 7803 inner ring is now 92mm BCD. Everything else is 74mm. The middle ring is unusually thick and is the unique D-type.

Again, he was talking about the DA triple - a very different animal from the DA double.

Rutnick

ahh...

My bad. I've never used a road triple except friction shift a touring bike and that's using a 25 year old crank.

Sheldon Brown

Right.

I always dis the Dura-Ace triple that locks you in to the *-39-30 gearing, but there's nothing wrong with the Dura-Ace double, if a double with minimum size of 38 teeth meets your needs.

Sheldon "Twos And Threes" Brown

grolby

I'll have some relish actually. I don't what got into me in this thread. I can only assume that I was having a bad day. Sorry!

That said, in what way is this a problem? Is the issue one of the spacing between rings not matching the shifter throw? Of the rings not being able to be installed? My assumption was the "thickness" being discussed was the thickness of the teeth, and that the 'problem' was that an Ultegra chain would not engage properly with, say, a 105 ring. In this case (this is what I thought was meant), there would be no problem - all 10-speed chains and rings are to the same spec. Making the thickness different where it is bolted to the crank is still pretty stupid, but it's believable stupid - and appears to be reality stupid. Sorry about the confusion.

Motorad

Okay, here's a double-chainring swapping question for the gang:

I have a Dura-Ace double crankset Bag-O-Stuff waiting at my LBS, along with my roadie bike frame. NOTE TO SELF: do not say gruppo ... do not say gruppo ... do not say gruppo ...

My DA double ring Bag-O-Stuff came with a 53-39T crankset ... to save money when I bought an available DA double crankset group ... that we intended to swap the outer 53T ring for a 50T. It was my original idea to wind up with a DA 50-39 double crankset ... and a 10-Speed (DA-CS-7800)) 12-27 cassette, when I bought the DA double crankset group.

However, having put 500 miles on my Saluki in Southeast Michigan, I now know that I need gears lower than 39/27 (hey, I'm old). Now that I'm learning how to properly number-crunch gear inches (thanks to you guys), and see the gear inches provided by a 700 x 25C ... 50-34T ... 12-27 10-speed, I'm mighty tempted to go with my current DA double crankset ... but to replace the 53-39T (50-39T) with a separate crankset: 50-34T.

Said all the above to ask the following question:

With my current DA-7800 double crankset Bag-O-Stuff ... and with the Shimano upgrades as of this point ... what would be the recommended 50-34T crankset for my DA 7800 group: The FC-R700 (apparently no special front derailleur required) ... or ... the 2008 Ultegra SL's FC-6650-G (will this work with the 7800 group?)?