Bicycle Mechanics - Campag Centaur 2005 bottom bracket

Does anyone here know for sure what's inside a Centaur 2005 bottom bracket? It's called 'Centaur' rather than AC-H or AH-S like the previous ones and has internal notches for the tool, rather than the external notches. I've had bad experiences with the older model and want to know if the new one is actually any better. I seem to remember reading somewhere that the internals were the same as Chorus, but I might be imagining it... Can't find the answer on the Campag web site either.

cheers

Does anyone here know for sure what's inside a Centaur 2005 bottom bracket? It's called 'Centaur' rather than AC-H or AH-S like the previous ones and has internal notches for the tool, rather than the external notches. I've had bad experiences with the older model and want to know if the new one is actually any better. I seem to remember reading somewhere that the internals were the same as Chorus, but I might be imagining it... Can't find the answer on the Campag web site either.

cheersit's supposedly upgraded. If it's like chours, the cartridge bearings can ce gotten to for replacement by pulling off the threaded end cups.

What problems did you have with the AC-H and AC-S? I got over 15000 miles out of my original AC-S, and replaced it in Jan of 04 with an AC-H.

Only real drawback with the AC-H is that it's heavier than a BB-6500 or Chorus so it ends up being the weak point in a Centaur groupset, if you're racing. Otherwise it's fine. It is certainly smooth enough and low maintenance. I'm running one right now.

Only real drawback with the AC-H is that it's heavier than a BB-6500 or Chorus so it ends up being the weak point in a Centaur groupset, if you're racing. Otherwise it's fine. It is certainly smooth enough and low maintenance. I'm running one right now.Yeah, 66 grams will keep you off the podium every time. But you make about 20 back by running the centaur crank over the chorus.

I had no problem with the 66 grams, but I did have a problem with the play in the thing after only 5000km and the resultant drivetrain roughness and noise. I don't want that again... Otherwise the Centaur setup is great.

Yeah, 66 grams will keep you off the podium every time.

Sydney, no one said that these trifling masses is a big deal or could change outcomes. Many people, certainly not me, will spend spend three times as much on a stem that weighs 66 grams less, that is a fact among racers and competitive club ride guys. My acknowledging the perception that the AC-H was the perceived weak point in the Centaur gruppo is not tantamount to your implication.

Sydney, no one said that these trifling masses is a big deal or could change outcomes. Many people, certainly not me, will spend spend three times as much on a stem that weighs 66 grams less, that is a fact among racers and competitive club ride guys. My acknowledging the perception that the AC-H was the perceived weak point in the Centaur gruppo is not tantamount to your implication.Excuse me, but weren't you the one that mentioned weight as being the drawback . I'm sure I had the comprehension switch in the on position,but I'll be sure to reset it this morning.

http://tinyurl.com/3o882

It has been upgraded the new centaur should be last years chorus. just like last years chorus was the previous years record for the most part.

But there will always be the fact that Chorus=asymmetrical, Centaur=symmetrical
factor. I have not checked out the new Centaur 2005 BB but I just remembered in contrast with my previous posting that at least one reliable source, Suzy Jackson, had issues with AC-H that were not connected with its weight, but rather its lifespan, I believe. Thing is, Greenfish sells them for $15.95, so you could buy three. One other disad of AC-H and AC-S, SC-S, is the installation tool, which is slip-prone. I can get the cups tight enough with that thing so I have never heard a peep from the BB, but others differ.

For those who want Centaur primarily for the "ergopower with low mass for low $" you could consider dispensing with Campag crankset altogether and go for a third-party brand. I'm impressed with Ritchey WCS V double (130mm BCD, not 110) with BB-6500, but Ultegra, FSA, and Truvativ are good alternatives too. IF you are on the other hand a religious devotee of Campagnolo, this is out of the question! Left ergos have no problem shifting over any crankset.

Thanks guys, my understanding was that the new one was last year's Chorus as rastabike stated. I hope so. Can't afford to upgrade cranks as well as buy a new bottom bracket, so this thing better be good and last longer than 5000km...

Here is some information found on the Campagnolo website regarding two of these bottom brackets.


CENTAUR™ Bottom Bracket
ITA, EN ; 111mm
cartridge b.b. - hollow axle - light alloy cups and spacer - for double and triple cranks with seat tube Ø 28.6 mm
233 g

AC-H™ bottom bracket
ITA, EN ; 111mm, 115.5mm
cartridge b.b. - hollow axle - light alloy cups - for double crankset: axle L. 111mm - for triple crankset: axle L. 111mm for Ø 28.6mm seat tube- for triple crankset: axle L. 115.5mm for Ø 32 or 35 mm oversize seat tube
288 g

This seems to imply to me that you cannot run the CENTAUR™ bottom bracket with any seat tube diameter other than 28,6 mm.

Is this true, and why would that be? Q-Factor? Shell width?

One other disad of AC-H and AC-S, SC-S, is the installation tool, which is slip-prone. I can get the cups tight enough with that thing so I have never heard a peep from the BB, but others differ.


Bingo!

It's a craptacular design for installation/removal.

Bingo!

It's a craptacular design for installation/removal.

You guys need to get the Tacx BB tool for said BB. It threads into the spindle. No slipping.

agree with Waldo...the Tacx BB cartridge tool is best to reduce tendency to strip the female splined BB interface as compared to using the Park BBT-5 splined plug which is also used on Campy's rear cassette lockring. I believe its a matter of how its done. You have to keep a fair measure of axial force on the BBT-5 plug with that level of torque to keep the splines from stripping. Using an open end wrench may not be the best approach. Better to use a socket over the plug (with torque wrench) with the palm of your hand putting a fair measure of axial force on the plug. The BB torque spec BTW is about the same as recommended for the rear cassette as shown below so the spline does have sufficient diameter and surface area to accomodate that level of torque. Kind of reminds me of the comparing 12 point sockets to 6 point...most who wrench a fair amount know which offers the best engagement without stripping.
George

Probably a stupid question but a Veloce 115.5 AC-H bottom bracket can be used with my 2006 Centaur Triple Crank right? I have a 32mm seat tube. Thanks

It has been upgraded the new centaur should be last years chorus. just like last years chorus was the previous years record for the most part.

This is another Urban Myth...That was true in the 90's and the carbon parts but, is not strictly true today although the slipping wrench and dinged paint in installing the AC-H improved with the internal tool adjustment on the new centaur BB.

The new Centaur is beautifully machined and finished. It's also very smooth. I'm running one now on my Daytona 10 sp bike. It functions light years ahead of the old AC-H version. Actually, it's on par with Chorus for less money.


Tim

agree with Waldo...the Tacx BB cartridge tool is best to reduce tendency to strip the female splined BB interface

And there are many other manufacturers that make such BB tool. It's just something that makes sense - in fact, my first BB tool had that feature.

You guys need to get the Tacx BB tool for said BB. It threads into the spindle. No slipping.
I'm not familiar with the older Campy bb tool but can a suitable length M8x1.0 bolt be run through the tool and threaded into the spindle end to clamp the tool in place?

I do this with a Park BBT-2 used for Shimano square taper bottom brackets and it positively prevents the tool from slipping.

I have a newer ('06) Chorus bottom bracket and both the Park BBT-5 and Performance's Spin Doctor (Lifu) Campy bb/lockring tools. Both can be clamped in place with a bolt if necessary.

There's a post in here somewhere that says a QR skewer can be used to hold the Campa BB/cassette tool (new style BB) so that it won't come off and possibly break something while applying torque.

There's a post in here somewhere that says a QR skewer can be used to hold the Campa BB/cassette tool (new style BB) so that it won't come off and possibly break something while applying torque.
I use the QR skewer to hold the Park BBT-2 in place when working on Octalink (works with ISIS also) bottom brackets. If the Campy square taper axle is hollow I guess it could be used there too.

It's easy to keep a BBT-5 from stripping the splines in a Centaur or other Campy BB...just fit the tool onto the cup, then put a few washers over it and loosely thread a crank fixing bolt into the spindle to keep everything in place. The only difference between this approach and the pricey Tacx tool is that the Tacx fixing bolt is spring loaded so that it keeps a constant force on the splines as the cup moves in or out, whereas with the crank bolt trick you have to stop periodically to adjust the bolt tension (depeinding on whether you are installing or removing the BB) in order to keep the tool firmly engaged but not binding.

One nice thing about the the BBT-5 (besides cost) is that you have the capability of using a torque wrench via a readily available 1" deep socket if you want, whereas the Tacx is too bulky be useable with commonly available sockets (though I'm sure you could find something with enough effort and money).

You can also use a similar trick for an AC-S or AC-H, you just may need bigger washers depending on which tool you're using. I have the Park spanner, and I think at one point I ended up using a left-side crank arm as a sort of washer. It was bulky enough to keep the Park tool in place (had I known about the Tacx tool at that time it would have saved me a lot of grief however)