Is there a science to building metal bike frames?

[Black Dog]

Originally Posted by joevers

You're right.

For a lot of these modern bikes though, they would consider the frame, fork, seatpost, stem, bars, and sometimes even the wheels as their frame design and sell them together as such. There's not much benefit to copying the design of metal round tubed bikes because they don't have the same constraints and characteristics. A lot of modern cockpits on Cervelo, Cannondale, Specialized etc. are absolutely one of the biggest design features of a bike, and they're really not designs that are possible with metal bikes.

I guess take that for what it's worth. You're right that it's not an apples to apples comparison, but that's kinda the point. Composite frames don't have the design constraints and as such can be modified quite far from the design of a normal steel bike. The S5 is an example of a bike that in no way is influenced by metal frame design and as such uses its own seatpost, stem, and bars so it's not directly comparable to something like a Richard Sachs which obviously does not have those things.

All good points, but how many watts does the integrated bar and stem save? You can put analogs of an integrated bar stem on a metal bike. As for seat post, again this is a minor gain and you can also run somewhat aero seat posts in a metal bike (besides the fact the seat posts sit in very dirty air). Internal cables have been available on metal bikes forever as well (not completely internal, granted). You can run very aero wheels on any bike. At the end of the day, it is tube shape, tube placement, some exposed cables, and some improved bar/stem integration. When added up this still does not provide the massive speed differences that are being claimed, even with round tubed steel frames.

[fa63]

Technically speaking, of course there is a science to building metal bike frames. Heck, there is an entire field called materials science dedicated to understanding how materials behave

But in reality, I imagine most builders are limited to what is available to them from tubing suppliers. Some might have the name / cachet to collaborate with tubing manufacturers to develop their own tubing, but this seems rare. Others might have the means and tools to butt their frames in-house based on a rider's specific needs, but I would be surprised if they actually "crunch the numbers" to decide exactly where and how much butting needs to take place. Instead, it is probably based on their previous experiences (though I could be totally wrong).

[Mark McM]

Originally Posted by fa63

But in reality, I imagine most builders are limited to what is available to them from tubing suppliers. Some might have the name / cache to collaborate with tubing manufacturers to develop their own tubing, but this seems rare. Others might have the means and tools to butt their frames in-house based on a rider's specific needs, but I would be surprised if they actually "crunch the numbers" to decide exactly where and how much butting needs to take place. Instead, it is probably based on their previous experiences (though I could be totally wrong).

And for lugged frames, builders are further limited by the availability of lugs, which limits tube shapes and diameters, and also limits joint angles.

For carbon frames, a molds can be quite expensive, and "once the mold is set" you can't change the shape of the mold/frame. However, carbon frame builders can relatively easily change the fiber types, layers and layups, which can allow them to tune the performance characteristics of the frame.

[Frankwurst]

Just ride.

[vespasianus]

Originally Posted by GregL

http://www.thetallcyclist.com/wp-con...Seven-Test.pdf

What is interesting is that current steel frames are running in the 1800 gram range - pretty much identical to an old neuron tubes bike from 1985.

Now the new OS Spirt tubing is very different than those old small diameter tubes but still...

[qnz]

Originally Posted by uber

To the OP, I am wondering why you are asking this question?

I like window shopping bike frames and I see beautiful IG posts from custom builders like Stelbel, no22, donhou, mosaic, and the list goes on. They each will build you a bike with custom geo. What they differ in is what metal they use, bottom bracket choice, and shape of the tubes.
But what if the geo you request is ass or what if the titanium frame you choose isn't as fun to ride than if you picked Columbus spirit tubing? Each builder will make you a bicycle shaped object but no "testing" that it is a good combo.

But what I've been reading is there is no best choice and you should pick the prettiest bike that gives you the warmest fuzzy feeling inside.

[martl]

Originally Posted by Black Dog

All good points, but how many watts does the integrated bar and stem save? You can put analogs of an integrated bar stem on a metal bike. As for seat post, again this is a minor gain and you can also run somewhat aero seat posts in a metal bike (besides the fact the seat posts sit in very dirty air). Internal cables have been available on metal bikes forever as well (not completely internal, granted). You can run very aero wheels on any bike. At the end of the day, it is tube shape, tube placement, some exposed cables, and some improved bar/stem integration. When added up this still does not provide the massive speed differences that are being claimed, even with round tubed steel frames.

Agree. I did comparison tests a while ago, same bike, different wheels.
Put the bike and wheels in my car and drove to an olympic rowing site - square course, wind shielded by banks, 4km absolutely level test track.

One set of classic low profile rim (cxp33), a set of deep cfk rims 12/20 spokes, one run with a rear disk.

We all agree that the wheels make the biggest difference aerodynamically on a bike?


I had a hard time measuring differences. At a test speed of ~36km/h between best and worst setup there lay maybe 10 Watts or 1/2 a km/h at same Wattage (meaured by SRM Pro). That is significant in a TT, but we are talking a full TT setup vs. climbing wheels here.

Now, how much does that NASA approved aero brake cable routing bring, that will noticeably catapult me across a parking lot, you were saying?

[uber]

To the OP.
I totally get it. Even with all the testing that a larger company might employ, at the end of the day, it is what you like to ride. The proof is always in the riding experience, so test riding is pretty valuable to me. To your point with a custom builder, we are relying on their experience to figure out material choice, angles, etc to make the bike perform and feel the way we request. And at some point, it is a leap of faith in the builder. Sometimes it doesn't work and sometimes it is magic.
With all the objective testing, I did not care for a Tarmac or Venge, but a Bianchi Oltre 4 felt great. I had a stock steel frame from a builder that was drop dead beautiful but just "meh" to ride. Sold it. A custom geo frame from the same builder rides perfectly for me. Get on a Sachs, Pegoretri, Speedvagen or DeSalvo. All steel, all different experiences.
Have you ridden any particular bikes that you love or don't love?

[gibbo]

The science or “magic” of a small boutique frame builder is the ability to get to know their customer and actually build a frame specific to that customers needs and desires. If you can articulate what you characteristics you desire a good builder should be able to deliver a particular geometry and tub set to match. On top of that you can spec details like BB, HS, cable routing, paint..... end result should be bliss! I think material is only one aspect of the build, Ti, steel, or carbon can all make great bikes, but a bike built for the masses will never be quite the same as something crafted by hand specifically for you.

Just my 2 cents.....


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[fa63]

The question is, how does a frame builder go about the process of choosing the appropriate tubeset for a given rider? Do they have a mathematical model where they enter the desired parameters and it calculates the correct tube size? This seems unlikely. It is more likely that their selection is based on their past experiences, based on feedback from similar riders, projected to the current customer. If true, this seems like it could be problematic, as most people who have paid for an expensive custom frame are likely biased as to how the frame rides so the feedback may not be very accurate.

While it is also science to experiment and use the data/feedback to drive your decisions, but what happens if the feedback loop is inaccurate because of human psychology?

Originally Posted by gibbo

The science or “magic” of a small boutique frame builder is the ability to get to know their customer and actually build a frame specific to that customers needs and desires. If you can articulate what you characteristics you desire a good builder should be able to deliver a particular geometry and tube set to match. On top of that you can spec details like BB, HS, cable routing, paint..... end result should be bliss! I think material is only one aspect of the build, Ti, steel, or carbon can all make great bikes, but a bike built for the masses will never be quite the same as something crafted by hand specifically for you.

[.RJ]

Originally Posted by fa63

but what happens if the feedback loop is inaccurate because of human psychology?

Of course it is - we're full of bias. But the builders are all using off the shelf tubing, so the possible combinations are pretty limited, its hard to go too far off the reservation.

[charliedid]

Originally Posted by qnz

I like window shopping bike frames and I see beautiful IG posts from custom builders like Stelbel, no22, donhou, mosaic, and the list goes on. They each will build you a bike with custom geo. What they differ in is what metal they use, bottom bracket choice, and shape of the tubes.
But what if the geo you request is ass or what if the titanium frame you choose isn't as fun to ride than if you picked Columbus spirit tubing? Each builder will make you a bicycle shaped object but no "testing" that it is a good combo.

But what I've been reading is there is no best choice and you should pick the prettiest bike that gives you the warmest fuzzy feeling inside.

These builders you mention design and build the bike around a series of measurements and ride quality/usage desires not you.

I could be wrong but I don't think any of them let you choose the geo or tubing.

Frankly the "no testing" comment is dubious IMO these people know and ride the bikes they make every day.

[parris]

OP the way it worked when I ordered my Kirk several years ago was that there was a number of body measurement sheets, current bicycle measurement sheets, a question sheet about my preferences, experiences, issues, etc. Then there was a good number of email as well as phone contact so that DK could get an understanding of what I was looking for.

After the process he designed a frame set and sent me the bike cad drawing.
There was then more communication with for lack of a better term "Q&A". He was able to answer the questions easily and the reasoning behind the choices he came up with for the whole package of frame design.

It's important to trust the chosen builder for his/her design chops. They as a general group are very good at answering those questions that come up design and build wise. Many of them will not build a bicycle with whacked out geometry or tubing spec. Their name and reputation goes on the down tube of every frame that goes out the door.

My understanding is that other good experienced builders all pretty much follow similar good working practices.

[gibbo]

Originally Posted by parris

OP the way it worked when I ordered my Kirk several years ago was that there was a number of body measurement sheets, current bicycle measurement sheets, a question sheet about my preferences, experiences, issues, etc. Then there was a good number of email as well as phone contact so that DK could get an understanding of what I was looking for.

After the process he designed a frame set and sent me the bike cad drawing.
There was then more communication with for lack of a better term "Q&A". He was able to answer the questions easily and the reasoning behind the choices he came up with for the whole package of frame design.

It's important to trust the chosen builder for his/her design chops. They as a general group are very good at answering those questions that come up design and build wise. Many of them will not build a bicycle with whacked out geometry or tubing spec. Their name and reputation goes on the down tube of every frame that goes out the door.

My understanding is that other good experienced builders all pretty much follow similar good working practices.

This is very similar to my experience with Baum. The process takes time, but it is worth it.


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[gibbo]

Originally Posted by fa63

The question is, how does a frame builder go about the process of choosing the appropriate tubeset for a given rider? Do they have a mathematical model where they enter the desired parameters and it calculates the correct tube size? This seems unlikely. It is more likely that their selection is based on their past experiences, based on feedback from similar riders, projected to the current customer. If true, this seems like it could be problematic, as most people who have paid for an expensive custom frame are likely biased as to how the frame rides so the feedback may not be very accurate.

While it is also science to experiment and use the data/feedback to drive your decisions, but what happens if the feedback loop is inaccurate because of human psychology?

I don’t think small builders are using mathematical models. Experience and feedback from customers, combined with riding what they build is the method typically used. It seems to work quite well for most builders, but it is important or a purchaser to do their research and find a builder that has experience creating something similar to what you want.


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