# Centaur Black/Red - More Torx?



## wannabeSWIFTer (Mar 8, 2006)

I picked up the Centaur Black/Red group because I didn't want to go 
to 11 speed. All my other bikes (and wife's) are Campy 10 speed.
I also think the Black/Red group looks really slick.

Anyway, I'm building up the bike and was surprised by how many
bolts are now using Torx instead of Allen.
The chain ring bolts are Torx.
The shifter clamp bolts are Torx.
I think the rear derailleur hanger is Torx, and this is really where my
question comes in. Every rear derailleur I've ever put on used a 5mm Allen wrench. The derailleur manual says to use a 5mm Allen, but a 5mm does not fit. A 4mm is too small. It looks like a Torx, but my torx 27 was too small and 30 too big. The inside (frame side) of the derailleur took a 27 and I was able to thread it on the hanger from the inside of the frame. 

Anyone else run into this?

Seems I used to be able to carry a single 5mm key and could adjust almost everything on the bike. Now I need a 5mm, some torx, 4mm 
for my stem. Why all the variability?

And the crank bolt, who the hell has a 14mm Allen key on hand. I sure didn't.

Just felt like ranting a little.


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## roadworthy (Nov 11, 2011)

wannabeSWIFTer said:


> I picked up the Centaur Black/Red group because I didn't want to go
> to 11 speed. All my other bikes (and wife's) are Campy 10 speed.
> I also think the Black/Red group looks really slick.
> 
> ...


People rant about the silliest of things.
For a given head size/fastener dia. torx offers greater tool bit surface engagement and hence lower tendency to strip relative to torque applied. They have their place.


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## cs1 (Sep 16, 2003)

roadworthy said:


> People rant about the silliest of things.
> For a given head size/fastener dia. torx offers greater tool bit surface engagement and hence lower tendency to strip relative to torque applied. They have their place.


While that might be true you didn't answer his question. Is it a Torx or not?


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## roadworthy (Nov 11, 2011)

cs1 said:


> While that might be true you didn't answer his question. Is it a Torx or not?


Take a reading class.


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## DrSmile (Jul 22, 2006)

It's neither. The rear derailleur has to be tightened from the inside of the derailleur hanger (and yes it's torx). It's one of Campy's new complications. Campy moved to torx because a lot of their bolts are no longer steel. Anything aluminum is going to be Torx.


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## jmoryl (Sep 5, 2004)

I don't know if this applies to Campy, but I've heard that Torx is popular with auto manufacturers because it works better with automated/robotic assembly systems. Are there any engineers out there who can comment?

Aluminum bolts? I rather doubt that.....


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## DrSmile (Jul 22, 2006)

jmoryl said:


> I don't know if this applies to Campy, but I've heard that Torx is popular with auto manufacturers because it works better with automated/robotic assembly systems. Are there any engineers out there who can comment?
> 
> Aluminum bolts? I rather doubt that.....


What are you doubting? Campy specifically states that these bolts are aluminum. As per the OP's original question, the chainring bolts are aluminum (have been even before they went to Torx), and the shifter clamp bolts are aluminum (went to Torx at the same time they switched to aluminum). The brake retaining nut is also Torx on models where the nut is aluminum and not steel (most models now). Some of the rear derailleur hanger/pivot bolts are titanium depending on the model. This is the reason they went to Torx. 

If you don't believe me take a magnet to the bolts. You'll see pretty rapidly which ones are or aren't steel. And no, they aren't stainless.


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## DrSmile (Jul 22, 2006)

To demonstrate this further:










Those are all Campy shifter clamp retainers. The top (and middle left) are the new aluminum ones. Note the top left one failed on me due to corrosion. The bottom ones are all steel ones that have started to corrode. I have replaced both types with Ti ones.


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## roadworthy (Nov 11, 2011)

jmoryl said:


> I don't know if this applies to Campy, but I've heard that Torx is popular with auto manufacturers because it works better with automated/robotic assembly systems. Are there any engineers out there who can comment?
> 
> Aluminum bolts? I rather doubt that.....


Dr. Smile is correct about bolts being aluminum to reduce weight. But torx are becoming pervasive jmoryl for the simple fact that they improve engagement and mitigate tendency to strip for same level of torque applied to allen screws. If you look at a torx fastener, you can measure the amount of surface area contact increase...its considerable. Allen configuration is also closer to a round shape and a Torx config. has contact surfaces more opposed to direction of prevailing torque. Torx are the present and the future. In fact, I just built a deck with torx deck screws. If you haven't used these, they are the bomb. Much less axial force required for much higher torque application compared to Philips which of course has less torque cabability compared to an allen.


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## jmoryl (Sep 5, 2004)

Dr. Smile - thanks for the examples.... I'm just glad most of my Campy stuff is older!
My mid-2000s Record crankset (square taper) has Al chainring bolts, which I knew about. But the others: I would swap them out too, probably for stainless if possible.

I've heard the arguments about Torx contact surface area being superior, but I'm still not convinced. Most of my Campy allen head fasteners seem deeper than the equivalent Torx versions, so less likely to strip. This seems to be borne out by my experiences working on cars (I never strip anything on my bike because I'm really careful there and the fasteners are easier to access).


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## flatlander_48 (Nov 16, 2005)

jmoryl said:


> I've heard the arguments about Torx contact surface area being superior, but I'm still not convinced. Most of my Campy allen head fasteners seem deeper than the equivalent Torx versions, so less likely to strip.


They are superior. But, you second sentence above is the clincher, so to speak. Where possible, bike folks like to use low-head screws. And yes, the hex heads are deeper which means the head is taller which means that the screw Weighs More than a low-head version. So, the Torx has more contact surface for the same type head. But when you compare a low-head Torx to a standard height hex head, the wrench contact area may be about the same but the Torx will be lighter in the low-head configuration.


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## roadworthy (Nov 11, 2011)

flatlander_48 said:


> They are superior. But, you second sentence above is the clincher, so to speak. Where possible, bike folks like to use low-head screws. And yes, the hex heads are deeper which means the head is taller which means that the screw Weighs More than a low-head version. So, the Torx has more contact surface for the same type head. But when you compare a low-head Torx to a standard height hex head, the wrench contact area may be about the same but the Torx will be lighter in the low-head configuration.


Well stated. Lower head height for the same engagement and same resistance to stripping at higher torque range with less tool penetration. Lower screw head height is less intrusive and weighs less when counting grams in bike applications. Further a shallower torx screw is a bit less sensitive to wrench angle compared to a deeper female allen hex.


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