|? Bianchi XL Boron...Dedacciai EOM 16.5....Perogetti GGM..??||sprockets2|
May 20, 2002 8:04 PM
|Several questions for those of you in the know:
1. Does the XL Boron use the Dedacciai EOM 16.5?
2. How/why does the GGM (which has that tubeset) use HUGE diameter tubes (like an old Cannondale), and what appears to be constant diameter-and quite thick-stays. The chain stays are slightly squished for that oval effect.
3. The XL Boron has almost normal looking tubes, and a more traditional taper in the stays. If these bikes are using the same tubes, I am stumped. Any comments are appreciated. Thanks in advance.
|re: ? Bianchi XL Boron...Dedacciai EOM 16.5....Perogetti GGM..??||Rusty Coggs|
May 21, 2002 5:14 AM
|I don't know that that the Biachhi xl boron is the same as eom16.5,as bianchi tends to be pretty unspecific about exactly hat they are using. But, I have never seen EOM hyped as having Boron in it.In any event,EOM is drawn into many different configurations depending on who specs it.Therefore appeaances mean nothing.|
|Dedacciai tubing info||Nessism|
May 21, 2002 5:29 AM
|Dedacciai likes to use a steel that they call 18MCDV6. They use both heat treated and non-heat treated versions of this material depending on the application. The EOM 16.5 tubes are further treated to a media blast process similar to shot peening to relieve stress and ward off crack propogation. I'm not sure how the Bianchi tubing falls into this family, but it should be in there somewhere.
As far as the tube sizes go, the "standard" EOM 16.5 road tubeset, as listed on Dedacciai's web site, indicates the use of the "huge" tube sizes - not sure about the chainstays though. The EOM 16.5 tubes are quite thin so maybe these diameters are needed to stiffen up the frame? By choosing smaller tubes, the Bianchi frame is likely to be more flexable.
Check out the following link for some tubing specs. When looking at the ultimate strength numbers listed for the steel materials, keep in mind that this number is the maximum strength and not necessarly the the strength of all tubes in that set.
|Dedacciai tubing info||slow-ron|
May 21, 2002 7:29 AM
|From Bianchi's web site, XL boron is water quenched, tempered & heat treated for a final tensile of 1800n/mm^2. No mention of bead blasting or shot peening. Thickness is .06mm at the butts and .04mm in the center but they don't provide the O.D.
Sir Ness, doesn't standard Dedacciai tubing have a lower tensile number?
If so this might explain why Bianchi can build the bike slightly smaller O.D. tubes and still get a decent ride out of it vs. EOM 16.5 pipes. The Bianchi tubes would be more rigid but the moment of inertia would be lower. Both bikes would, relatively speaking, resist torsion or deflection about the same.
Just a thought.
|Dedacciai tubing info||Nessism|
May 21, 2002 8:36 AM
|Frankly speaking, I was just assuming that the metal used for the Bianchi tubing would be the same as the Dedacciai branded stuff. Maybe they're using a special material and/or special heat treatment process for Bianchi. Or maybe, their is some confusion between ultimate strenght vs. yield strength? Not sure. Dedacciai states Rm = 1600 N/mm**2 but I'm not sure what Rm means.
Stronger metal is not stiffer metal since it is the Modulus of Elasticity (E) that determines stiffness. E does not change much within a family of materials and pretty much all steel materials have the same value - 30 Mpsi.
Given that, the Bianchi tubes will be more flexable since they have a smaller moment of inertia as you noted. As a note, some people have reported failures of these super light Bianchi frames. I'm not sure what the failure rate is however so this information may not be significant.
|Dedacciai tubing info||slow-ron|
May 21, 2002 10:56 AM
|In my reasoning I forgot that even if the yield goes up, E and G remain constant. Shouldn't have slept during that college course.
Does it really matter how much more the tubing companies are able to increase the ultimate strength of these tubes? In my mind it doesn't matter whether you can bend it 5" or 8" until it breaks, it still bends more than you want for a bicycle frame.
May 21, 2002 11:28 AM
|One nice thing about the stronger materials is that they are harder to dent given the same wall thickness. Other than that, their is a point of dimishing returns on the strength increases.
One other thing about these super high strength steels, often the material elongation property goes down as strength goes up past some point. The elongation is important since it relates to brittleness - or lack there of.
|Some info from the Bianchi website||Nessism|
May 21, 2002 10:24 AM
|Regarding the steel tubing they use:
"Dedacciai, which has created special tubes for Bianchi, produces a steel with exceptional characteristics. It's a particular microalloyed HSLA material (High Strength Low Alloy) initialled 18MCDV6HT which has reached the amazing breaking load 1,400 N/mm2. The Dedacciai tubes have triple thicknesses, special profiles like LTP (Low Torsion Profile) studied to reduce the lateral torsion of the frame in the acceleration phase and the weight thanks to asymmetric reinforcements in the development and differentiation in the thicknesses."
May 21, 2002 1:06 PM
|Bill--who posted the race story below--has a Pegoretti Marcelo and may have some answers for you. I've had a quick spin on his bike and a short (maybe 6 miles) test ride on the XL Boron. My marginally imformed thoughts:
1) Both bikes are light--built with good components and good wheels these were two of the lightest steel bikes I've seen anywhere.
2) Both bikes offered appealing--although somewhat different--rides. You feel a bit more flex with the Bianchi, but not so much as to be annoying at all (I'm 180 lbs or so--and I stomped pretty good on a climb on the Bianchi and didn't have problems). The Pegoretti felt more solid--beefy-assed-chainstays-from-hell seemed to shore things up. Solid, but not over-built--it's a really nice bike IMO.
3) I cannot imagine what you get with the GGM. My understanding is that the GGM offers even bigger over-sizing (or whatever you call it), especially on the down-tube and rear triangle. Maybe this is cool, but I'll note that the Marcelo is by no means a wimpy frame--really: this is a solid ride. So, unless you're a really big rider I'm wondering what the extra reinforcement (and weight) of the GGM is good for (and whether it's even desireable).
|I don't know squat about the technical details. BUT . . .||bill|
May 21, 2002 1:30 PM
|from what I've read and heard and picked up in dark alleys, the decision to spec the larger tubes for the GGM are as much cosmetic as anything. The GGM is bound to be a little stiffer than the Marcelo, which I believe is the same tubing (same wall thickness) with the same steel with tubes of marginally less diameter than the GGM, the resulting bike being a tad lighte than the GGMr, but the Pegoretti website and all of the marketing materials I've looked at don't tout any stiffness difference between the two bikes. All they say is that the GGM is supposed to look like an aluminum bike. A Cannondale wannabe (Pegoretti certainly seems obsessed with all things 'Murican). Style, not substance. I also get the idea that the GGM, with the larger tubes, is maybe a technical challenge, built because he can. |
I was a little worried that the Marcelo would feel too stiff, because it is supposed to be a little stiffer than the other steel Pegoretti's but for the GGM, but it's not too stiff at all. It's maybe a little stiffer than my Litespeed Natchez (1998 vintage). As Dan says, the Pegoretti is solid (much more solid than the LS) without really feeling stiff. For crit racing, you may even want a stiffer bike.