Materials (specifically steel), ride feel, and build details

[J.Higgins]

Perhaps the OP should look for a smaller version of his old steel Serrotta?

[NHAero]

It's not hard to size the diameter and wall thickness of the main tubes of a bike frame such that the same stiffness is achieved regardless of whether it is steel, titanium, or aluminum. The lower modulus metals will need more diameter or wall thickness or both.

I spent a lot of time analyzing this and with others testing many frames for their stiffness in bending and torsion in 1973-74.

You can read about it here and here.

In a bike frame, the tube that has the most significant challenge for the titanium and aluminum builder is the chainstay, because clearances are tight, and larger diameter is the strategy to maintain strength and stiffness while lightening the structure.

Originally Posted by Peter P.

Yet titanium DOES have a different spring rate. One spring manufacturer compares a titanium spring and a steel alloy spring with equivalent function. The titanium spring is 3" shorter for the same functional properties. Had they been the same length, their capacities would be considerably different.

Same with bicycle frame tubes; they way titanium and steel respond to flexing are different; like guitar strings of different materials.

The OP is not going to find that "feel" of his old steel Serotta, in a titanium frame.

[vespasianus]

Originally Posted by rain dogs

Columbus still makes SL tubing, and it is easily available. I think it is ever so slightly improved (Omnicrom) from the SL of old old days, but pretty similar. I'm hardly an expert.

If you want the same lightness and feel of an old slx frame, but made today, that'd likely be your best bet in Columbus. You can get 2,54cm top tubes, and 28,6 down tubes in 0,8/0,5/0,8

Everything else that is really thin wall - Spirit, Life etc. is oversize, no?

Zona is not so different and could be built with small diameter tubing. 0.8/0.6/0.8

Tommasini still sells the Sintesi with old style tubing (Columbus Neuron). Very sweet ride and at your weight, could be perfect.

[jasonification]

Originally Posted by J.Higgins

Perhaps the OP should look for a smaller version of his old steel Serrotta?

I wish!!! keeping my eyes peeled

[jasonification]

Originally Posted by vespasianus

Tommasini still sells the Sintesi with old style tubing (Columbus Neuron). Very sweet ride and at your weight, could be perfect.

Great option. will look into that

[HenryA]

Way over thinking this. Mostly because you don't know what tubing is in most bikes. Sure its got a sticker on the frame that says "Magic Carpet Tubing" but which Magic Carpet Tubing and what thickness? What butting?

Talk with the person who is building your new frame and tell them what you like and don't like in the way the bike feels, then let them do their thing.

If you're buying something like another used Serotta, consider whether your weight is in the normal range for your height/frame size. If so, the frame should be good for what you want.

[jasonification]

Originally Posted by HenryA

Way over thinking this. Mostly because you don't know what tubing is in most bikes. Sure its got a sticker on the frame that says "Magic Carpet Tubing" but which Magic Carpet Tubing and what thickness? What butting?



Talk with the person who is building your new frame and tell them what you like and don't like in the way the bike feels, then let them do their thing.



If you're buying something like another used Serotta, consider whether your weight is in the normal range for your height/frame size. If so, the frame should be good for what you want.

While I agree that I'm probably overthinking it, I actually really appreciate all the knowledge I'm getting from the forum! On another note "magic carpet tubing" sounds like a perfect sticker for my next bike..

Sent from my HD1907 using Tapatalk

[Mark McM]

Originally Posted by Peter P.

Yet titanium DOES have a different spring rate. One spring manufacturer compares a titanium spring and a steel alloy spring with equivalent function. The titanium spring is 3" shorter for the same functional properties. Had they been the same length, their capacities would be considerably different.

(sigh.) There are multiple variables that affect the stiffness of a structure, including the material properities (modulus) and the geometry (diameters, lengths, thicknesses, etc.). When changing the material of a component (change in modulus), you can modify the other variables to maintain the same stiffness. Bicycle frame tubing is made in many diameters and wall thicknesses, so you can achieve the same stiffness whether using steel, titanium or aluminum.

It is true that titanium has a different modulus than steel - but modulus is not stiffness. Stiffness is function of both modulus and geometry. By varying the geometry (diameters, wall thicknesses), you can make titanium tubes the same stiffness as steel tubes, and they will react the same under load.

[tbike4]

Ritchey Logic. That is the answer, maybe. I don't know what tubes are used but it's my go to steel bike most of the time. With a 9100 group and 1400 gram wheels, the best 25's on there it is a fun ride.

My first “oh wow” moment on a steel bike was a Serotta Atlanta. I have a Tommasini Tecno Extra with shaped Columbus Genius tubes that has the magic steel feeling. Early 2000's I think.

[muz]

Originally Posted by Mark McM

By varying the geometry (diameters, wall thicknesses), you can make titanium tubes the same stiffness as steel tubes, and they will react the same under load.

Yes, but the converse may not be true. If you try to make a steel bike with the same stiffness as titanium, the tubes may not have enough dent resistance. Maybe not true for super high tech steel alloys like 953.

[Mark McM]

Originally Posted by muz

Yes, but the converse may not be true. If you try to make a steel bike with the same stiffness as titanium, the tubes may not have enough dent resistance. Maybe not true for super high tech steel alloys like 953.

I assume you mean at the same weight. That could be true - lower density materials can have a stiffness-to-weight advantage, as long as they are not space constrained. (For example, as NHAero noted above, chainstays are highly space constrained, so there is little opportunity to make them stiffer without increasing weight). But this discussion wasn't about making frames stiffer than steel, it was about making frames as "springy" (flexy) as steel tubes. Which can certainly done with titanium.

As an example, I have a bike with an exceptionally flexy frame. It's not just a matter of being able to "feel" it, you can actually see it When you stomp on the pedals, you can see the crank/chainrings flex from side to side. When you flick the handlebar bars quickly right and left, you can see the torsional flex in the front triangle as the frame twists. What is the frame made out of? Oversized titanium tubing (2002 Lightspeed Ghisallo).

[robt57]

My first Strong road frame built in 2000 is Foco [called Life now]. Still have it.

It isn't all Foco, TT is OX Plat and the DT is a pear shaped from I forget what Colubus set. I had it built after finding a few litespeeds too flexy 1996-2000]. Granted I didn't get into a Vortex or Ultimate due to price and crit geoms then.

I was a 190 lb muscle monster 20 years ago, and the 3.75lb powder coated frame was plenty stiff. He built it for what I wanted then. Decade later I pulled the AME fork for an HSC3 for some cush, it worked. I weight 200 now, more right after winter, and it is stiffer than I need by plenty as I ain't no monster in the power dept 20 years later @ 64.

It has a steel fork now as well. My 753 frame I have is a lot more flexy, but planes well pushing it for what constitutes FTP these days. But is surely a more forgiving roll....