What Frame Material Is The Best For A Tandem?
03-16-14, 05:03 AM
#26
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There are a lot of myths being brought to the front here.
The OP's aluminum frame was anodized based on a corrosion concern. It is known that aluminum alloys, especially the more exotic versions, are prone to corrosion and with it crevasse cracking. Aluminum or any metallic has the known property to build in stresses at any cross section change of the material. Also, all metallics can fatigue and fail. This is the proverbial beer can that is bent so many times until it fails. In these cases, known limits of elasticity are exceeded.
As for composites and in particular carbon based materials that are commonly used. Fatigue does not occur to the fibres. Carbon structure failures would happen in two formats. First is an adhesion failure, second is the explosive or catastrophic failure wherein the epoxies have no adhesion failure, but the carbon fibres are pushed beyond limits and fail violently.
To classify carbon superior on account of not having a frame fail is not a good statement either...it simply means that it is overbuilt, however the mode of failure when comparing metals to composites forces the designer to not even consider the implication of the carbon failure. In essence it would be ugly.
As for UV, that is a concern of the resin system. Depending upon the final use of the carbon fibres, in general terms, this determines the base material the fibres are made from and / or how many fibres are bundled together for processing. Aerospace fiber bundles are typically made from PAN, while other industry fibers can also be made from PAN, or other base materials, such as tar pitch or Rayon, may be utilized. Regardless of the process and base material, all fibres are produced at extremely high temps in a controlled environment. The idea of UV affecting carbon fibres is the equivalent of UV affecting the remnants of a campfire.
There is a lot more to the which is the best than what supports you fanny down the road.
PK
The OP's aluminum frame was anodized based on a corrosion concern. It is known that aluminum alloys, especially the more exotic versions, are prone to corrosion and with it crevasse cracking. Aluminum or any metallic has the known property to build in stresses at any cross section change of the material. Also, all metallics can fatigue and fail. This is the proverbial beer can that is bent so many times until it fails. In these cases, known limits of elasticity are exceeded.
As for composites and in particular carbon based materials that are commonly used. Fatigue does not occur to the fibres. Carbon structure failures would happen in two formats. First is an adhesion failure, second is the explosive or catastrophic failure wherein the epoxies have no adhesion failure, but the carbon fibres are pushed beyond limits and fail violently.
To classify carbon superior on account of not having a frame fail is not a good statement either...it simply means that it is overbuilt, however the mode of failure when comparing metals to composites forces the designer to not even consider the implication of the carbon failure. In essence it would be ugly.
As for UV, that is a concern of the resin system. Depending upon the final use of the carbon fibres, in general terms, this determines the base material the fibres are made from and / or how many fibres are bundled together for processing. Aerospace fiber bundles are typically made from PAN, while other industry fibers can also be made from PAN, or other base materials, such as tar pitch or Rayon, may be utilized. Regardless of the process and base material, all fibres are produced at extremely high temps in a controlled environment. The idea of UV affecting carbon fibres is the equivalent of UV affecting the remnants of a campfire.
There is a lot more to the which is the best than what supports you fanny down the road.
PK
03-16-14, 12:05 PM
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Not sure I'd trust a CF guy on that, I can find you steel builders who say otherwise. The independent stuff I've seen was inconclusive, but cf does fatigue over cycles regardless of stress, like aluminum. Steel and ti don't. I agree that it might be theoretical in application and I'm not a CF assplodes guy...I get your point.
03-16-14, 12:11 PM
#28
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03-17-14, 09:37 AM
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I don't know... I mean... storage? I'd crack too if I was rode hard and put away wet for 10 years"
That's a new one to me, can you explain how a frame will develop cracks by being idle for 10 years?
" I have a friend who owns a bike shop and he flat out won't deal with tandemists. I get a pass because my stoker is blind."
I don't know any bicycle shops in the Bay Area that would turn down work on a Tandem, as it is income to the bike shop.
"Seriously, if I ran Santana I'd void your warranty."
The reason for purchasing a Santana in the first place was how they said their warranty was the best, and yes, we did pay $4200. for this bike in 1996. From the Santana site is: All Santana frames are fully warranteed to the original owner against defects in materials and workmanship with no time limit.
"At least they are talking to you and offering to fix the frame, maybe even replace it."
Well, they don't respond to emails in a timely manner, I did have to call them and they needed for me to send them the frame for inspection. That is as far as it has gone. Hopefully this week, I will have an answer.
"Your frame, repaired by Santana should be perfectly serviceable for the rest of you and your mrs.'s natural lives."
This to me is the gray area, the frame has cracks on different ends of the frame. One crack, ok, repair it, two cracks, perhaps the frame hardness is too great. It would be a pity to have the frame repaired, painted and then have another crack show up in another area.
"BTW riding a tandem really isn't the best way to lose 50ish. It's too efficient. You need to waste energy in a big way. You're my age, I know what I'm talking about."
I disagree, back when we were tandeming, our total team weight was 300 lbs, now our team weight is 350. Riding a tandem to me equals the teams ability, and if you think that you didn't get the workout needed in the ride, you have your choice of adding more mileage or adding more climbing.
"So... cut your sugar intake by 1/2 or more. Do not replace it with Sucralose or Aspartame, Only Stevia or Xylitol. Skip lunch once in awhile. Do not snack. You aren't going to burn enough calories cycling so you have to keep them from going in in the first place. Some people call this dieting but I won't. It's lifeting. FWIW."
We do not add sugar or any other sweeteners, we have been on the low carb thing for many years (just good carbs) and stay away from junk food. It's all about calories in verses calories out, that is one big reason for me to get us both out riding again. And I do look forward to the company of my stoker (wife) on this journey!
Thanks for your thoughts, Mike
H
That's a new one to me, can you explain how a frame will develop cracks by being idle for 10 years?
" I have a friend who owns a bike shop and he flat out won't deal with tandemists. I get a pass because my stoker is blind."
I don't know any bicycle shops in the Bay Area that would turn down work on a Tandem, as it is income to the bike shop.
"Seriously, if I ran Santana I'd void your warranty."
The reason for purchasing a Santana in the first place was how they said their warranty was the best, and yes, we did pay $4200. for this bike in 1996. From the Santana site is: All Santana frames are fully warranteed to the original owner against defects in materials and workmanship with no time limit.
"At least they are talking to you and offering to fix the frame, maybe even replace it."
Well, they don't respond to emails in a timely manner, I did have to call them and they needed for me to send them the frame for inspection. That is as far as it has gone. Hopefully this week, I will have an answer.
"Your frame, repaired by Santana should be perfectly serviceable for the rest of you and your mrs.'s natural lives."
This to me is the gray area, the frame has cracks on different ends of the frame. One crack, ok, repair it, two cracks, perhaps the frame hardness is too great. It would be a pity to have the frame repaired, painted and then have another crack show up in another area.
"BTW riding a tandem really isn't the best way to lose 50ish. It's too efficient. You need to waste energy in a big way. You're my age, I know what I'm talking about."
I disagree, back when we were tandeming, our total team weight was 300 lbs, now our team weight is 350. Riding a tandem to me equals the teams ability, and if you think that you didn't get the workout needed in the ride, you have your choice of adding more mileage or adding more climbing.
"So... cut your sugar intake by 1/2 or more. Do not replace it with Sucralose or Aspartame, Only Stevia or Xylitol. Skip lunch once in awhile. Do not snack. You aren't going to burn enough calories cycling so you have to keep them from going in in the first place. Some people call this dieting but I won't. It's lifeting. FWIW."
We do not add sugar or any other sweeteners, we have been on the low carb thing for many years (just good carbs) and stay away from junk food. It's all about calories in verses calories out, that is one big reason for me to get us both out riding again. And I do look forward to the company of my stoker (wife) on this journey!
Thanks for your thoughts, Mike
H
Last edited by 1speeder; 03-17-14 at 09:41 AM. Reason: spelling
03-17-14, 10:54 AM
#30
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I'd wait for Santana's response before worrying any further. If it's a warranty repair then there shouldn't be any charge for paint or other associated labor and parts. When I've had frames replaced under warranty (albeit not by Santana) it hasn't cost me anything (other than being without the bike for a short period). I would also tend to trust Santana's judgement on the soundness of the frame. They should have lots of experience by now and presumably don't want anyone riding on frames that may be unsafe with their name on the sides.
Santana's warranty isn't worth the paper it is printed on, (Which is to say it's not printed anywhere. It only exists, as far as I can find, in HTML).
I suspect, it probably won't be the last tandem 1speeder buys as he hoped, but likely the last Santana.
03-17-14, 03:43 PM
#31
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[QUOTE=or a tube with a patch
....just sayin'.......[/QUOTE]
In 60+ years of cycling and repair of countless tubes, I have never had a correctly applied patch fail. Just sayin'
....just sayin'.......[/QUOTE]
In 60+ years of cycling and repair of countless tubes, I have never had a correctly applied patch fail. Just sayin'
03-17-14, 05:48 PM
#32
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10,000 miles on a quality tandem or single bike . . . and frame failure?
At that kind of mileage we consider a bike to be just 'broken in'!
Have had 3 steel custom tandems that lasted/performed well for over 50,000 miles.
Our current c/f tandem has around 40,000 miles on the odo.
Having said that, failure can happen due to crashes, fatigue, or even the builder taking a coffee break and screwing things up!
Have even seen one builder (un-named) smoking a joint while brazing . . .
At least you spotted the break and it did not cause you physical any harm.
Our 2 frame failures and broken fork did not cause us to crash but pilot noted that something wasn't quite right.
It pays to give any bike a regular once-over for any issues.
Good luck and get back to riding TWOgether!
Rudy and Kay/zonatandem
At that kind of mileage we consider a bike to be just 'broken in'!
Have had 3 steel custom tandems that lasted/performed well for over 50,000 miles.
Our current c/f tandem has around 40,000 miles on the odo.
Having said that, failure can happen due to crashes, fatigue, or even the builder taking a coffee break and screwing things up!
Have even seen one builder (un-named) smoking a joint while brazing . . .
At least you spotted the break and it did not cause you physical any harm.
Our 2 frame failures and broken fork did not cause us to crash but pilot noted that something wasn't quite right.
It pays to give any bike a regular once-over for any issues.
Good luck and get back to riding TWOgether!
Rudy and Kay/zonatandem
03-17-14, 08:36 PM
#33
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Apologies, I know it's one of those perennial head ache issues and, as others alluded to, it's an area where it is very hard for a consumer without a metallurgy degree and product expertise in bonding and plastic fibers to determine good information from bad. There is just so much marketing and so much half understood data that I think it's impossible to know myth from reality. I will say that I use the very un-scientific approach of "I've seen more broken CF than steel, so I'll trust steel". That, and I'm not concerned about bicycle weight and prefer the aesthetics of steel. Our tandems also see commuting duty - meaning they are leaned into things - and I just trust steel more (rational or not).
03-17-14, 09:26 PM
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"What Frame Material Is The Best For A Tandem?"
IMHO Cro-Mo or Reynolds 531; steel.
Powder coating will stand up to anything that your body can put out.
IMHO Cro-Mo or Reynolds 531; steel.
Powder coating will stand up to anything that your body can put out.
03-17-14, 09:32 PM
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Don't sweat it, like I said, I'm not an Engineer but I have had a number of them working for me over the years and I have enough materials background/education to be dangerous. I can see where it can be confusing, especially for those of us with no materials education. As PMK pointed out, there is a lot of mythology. Unfortunately CF suffers from it's teething issues from 20yrs ago. CF technology has improved much as the years have gone by and manufacturers have learned what works and what doesn't.
I think the important thing to take from this is that if you purchase a higher end tandem from one of the good tandem builders, you should have a great bike that should last many, many years and tens of thousands of miles irregardless of the the material that it is made from.
I think the important thing to take from this is that if you purchase a higher end tandem from one of the good tandem builders, you should have a great bike that should last many, many years and tens of thousands of miles irregardless of the the material that it is made from.
03-17-14, 09:34 PM
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03-17-14, 10:02 PM
#37
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NOPE, I owned 2 Yeti MTB's back in the day (before suspension forks), Cro-Mo and powder coated, these frames didn't last long before I had rust stains coming out of everywhere on the top tube. So, I don't believe in powder coating! Even the old Salsa stems coating's failed under my sweat!
Mike
Mike
The ultimate though is electro-less nickel Stop rust + wear on road + mountain bikes | Electroless Nickel Plating
03-17-14, 10:44 PM
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Mike; there has been quite a bit of work on powder coat since then, due to environmental regulations around the world it has become the choice paint. Proper application is critical.
The ultimate though is electro-less nickel Stop rust + wear on road + mountain bikes | Electroless Nickel Plating
The ultimate though is electro-less nickel Stop rust + wear on road + mountain bikes | Electroless Nickel Plating
Thanks for your info,
Mike
03-18-14, 07:25 AM
#39
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Here is a good article from an authoritative source:
Frame Materials for the Touring Cyclist
Basically, how a bike ride depends not only on frame material, but also on tubing diameter, tubing thickness, geometry, how it is built, wheel choice, saddle choice, etc.
So, it is not only what material you use but also what you do with that material.
Also, what is "best" for one application may not be the best for another.
My first tandem was a chinese $150 Ebay steel tandem whose pedals fell off on the first ride, and chains constantly drop when switching gears. I worked with it enough to be able to ride the thing on the Houston-Austin MS150 the following week. We now ride on an aluminum mountain tandem, a home made carbon fiber hybrid, and a titanium road (with newly installed DI2). To me, they were/are all best bikes. We appreciate them all for the joy and memories they each provided us.
CJ
Frame Materials for the Touring Cyclist
Basically, how a bike ride depends not only on frame material, but also on tubing diameter, tubing thickness, geometry, how it is built, wheel choice, saddle choice, etc.
So, it is not only what material you use but also what you do with that material.
Also, what is "best" for one application may not be the best for another.
My first tandem was a chinese $150 Ebay steel tandem whose pedals fell off on the first ride, and chains constantly drop when switching gears. I worked with it enough to be able to ride the thing on the Houston-Austin MS150 the following week. We now ride on an aluminum mountain tandem, a home made carbon fiber hybrid, and a titanium road (with newly installed DI2). To me, they were/are all best bikes. We appreciate them all for the joy and memories they each provided us.
CJ
03-18-14, 08:09 AM
#40
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Mike; there has been quite a bit of work on powder coat since then, due to environmental regulations around the world it has become the choice paint. Proper application is critical.
The ultimate though is electro-less nickel Stop rust + wear on road + mountain bikes | Electroless Nickel Plating
The ultimate though is electro-less nickel Stop rust + wear on road + mountain bikes | Electroless Nickel Plating
03-18-14, 08:14 AM
#41
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If we're talking high end performance, high cost tandem, I don't think there's much doubt that you could make an amazing CF tamdem frame. But the CF frame that is most widely available is using older technology that pretty much is no longer used for CF singles , outside of the custom market.
The practical limitations on building CF tandems keep welded magnesium, and aluminum in the game as reasonable alternatives to CF.
All that said our next tandem will likely be CF, but we haven't ruled out a Paketa.
__________________
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
You could fall off a cliff and die.
You could get lost and die.
You could hit a tree and die.
OR YOU COULD STAY HOME AND FALL OFF THE COUCH AND DIE.
03-18-14, 08:18 AM
#42
Senior Member
With my limited background, here are my generalized opinions on the materials:
Steel - Heavy, durable, and easy to build. Bad tendency to rust. Good for touring bikes.
Aluminum - Cheap, light and better corrosion resistance. Larger diameter tubing needed.
Good for inexpensive bikes.
Carbon fiber - Light and stiff. Nice moldability for irregular shapes. Poor crash survivability. Great for light race bikes. Bad for mountain bikes.
Titanium - Light and durable. Great corrosion and scratch resistance. Larger diameter tubing needed for stiffness. Perfect for touring/travel bikes.
Magnesium - ?
CJ
Steel - Heavy, durable, and easy to build. Bad tendency to rust. Good for touring bikes.
Aluminum - Cheap, light and better corrosion resistance. Larger diameter tubing needed.
Good for inexpensive bikes.
Carbon fiber - Light and stiff. Nice moldability for irregular shapes. Poor crash survivability. Great for light race bikes. Bad for mountain bikes.
Titanium - Light and durable. Great corrosion and scratch resistance. Larger diameter tubing needed for stiffness. Perfect for touring/travel bikes.
Magnesium - ?
CJ
03-18-14, 09:22 AM
#43
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Sorry; I do not know the technically incompetent person who told you that colored anodizing would protect aluminum from attack by salty fluids. Anodizing for color is intentionally porous so that the colored dye will soak in, and then be cured. It is actually rather poor at protecting the aluminum underneath because it intended to be colored. All anodizing is porous, and stuff leaches into it, and out of it. It is like a sponge.
Professionally; I am a Mechanical Design Engineer with a very strong background in materials.
In your situation; look at what is used to protect structures in the ocean: electro-less nickel plating on all kinds of metals; brass; zinc plating on steel; etc. Aluminum is generally avoided for ocean applications that need to last a long time (military attack ships do not last a long time).
Luck has nothing to do with it - it is all about proper design and process of the protecting system.
I bet that any company would say that your sweat is an aggressive unreasonable attack on the frame; and chemical analysis would probably show that it is not different from dumping the frame in the ocean.
03-18-14, 09:35 AM
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With my limited background, here are my generalized opinions on the materials:
Steel - Heavy, durable, and easy to build. Bad tendency to rust. Good for touring bikes.
Aluminum - Cheap, light and better corrosion resistance. Larger diameter tubing needed.
Good for inexpensive bikes.
Carbon fiber - Light and stiff. Nice moldability for irregular shapes. Poor crash survivability. Great for light race bikes. Bad for mountain bikes.
Titanium - Light and durable. Great corrosion and scratch resistance. Larger diameter tubing needed for stiffness. Perfect for touring/travel bikes.
Magnesium - ?
CJ
Steel - Heavy, durable, and easy to build. Bad tendency to rust. Good for touring bikes.
Aluminum - Cheap, light and better corrosion resistance. Larger diameter tubing needed.
Good for inexpensive bikes.
Carbon fiber - Light and stiff. Nice moldability for irregular shapes. Poor crash survivability. Great for light race bikes. Bad for mountain bikes.
Titanium - Light and durable. Great corrosion and scratch resistance. Larger diameter tubing needed for stiffness. Perfect for touring/travel bikes.
Magnesium - ?
CJ
Last edited by waynesulak; 03-18-14 at 12:11 PM.
03-18-14, 11:01 AM
#45
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Hi Mike;
Sorry; I do not know the technically incompetent person who told you that colored anodizing would protect aluminum from attack by salty fluids. Anodizing for color is intentionally porous so that the colored dye will soak in, and then be cured. It is actually rather poor at protecting the aluminum underneath because it intended to be colored. All anodizing is porous, and stuff leaches into it, and out of it. It is like a sponge.
Professionally; I am a Mechanical Design Engineer with a very strong background in materials.
In your situation; look at what is used to protect structures in the ocean: electro-less nickel plating on all kinds of metals; brass; zinc plating on steel; etc. Aluminum is generally avoided for ocean applications that need to last a long time (military attack ships do not last a long time).
Luck has nothing to do with it - it is all about proper design and process of the protecting system.
I bet that any company would say that your sweat is an aggressive unreasonable attack on the frame; and chemical analysis would probably show that it is not different from dumping the frame in the ocean.
Sorry; I do not know the technically incompetent person who told you that colored anodizing would protect aluminum from attack by salty fluids. Anodizing for color is intentionally porous so that the colored dye will soak in, and then be cured. It is actually rather poor at protecting the aluminum underneath because it intended to be colored. All anodizing is porous, and stuff leaches into it, and out of it. It is like a sponge.
Professionally; I am a Mechanical Design Engineer with a very strong background in materials.
In your situation; look at what is used to protect structures in the ocean: electro-less nickel plating on all kinds of metals; brass; zinc plating on steel; etc. Aluminum is generally avoided for ocean applications that need to last a long time (military attack ships do not last a long time).
Luck has nothing to do with it - it is all about proper design and process of the protecting system.
I bet that any company would say that your sweat is an aggressive unreasonable attack on the frame; and chemical analysis would probably show that it is not different from dumping the frame in the ocean.
Thank you for your information! I was told by the bike shop when I was looking at a road bike tandem back in 1996 that this would be the best coating because of my sweat issue. I have read that there is also a sealer that could be applied over the anodizing to seal the coating. This is way over my head, so I have no clue if the sealing was part of Santana's anodizing procedure, or if this sealing process would seal out the salts from my sweat. There is no sign of corrosion inside or outside of the frame tubes from my sweat, just light staining ( a difference of color) in the purple anodized color. I don't believe the sweat is the cause of the cracks since 1 of the cracks is in the rear stokers seat tube where my sweat never reached.
It's going to be interesting what Santana is going to come up with.
Thanks again,
Mike
03-18-14, 11:36 AM
#46
Senior Member
As someone who sweat profusely (I was sweating in 50 degree temp biking this morning), live in the drenching humidity of the Texas gulf coast, and occasionally ride my bike on the beach, I am very concerned about the corrosion issue. Cheap stainless steel bolts will rust here after a few months. If rust is an issue, titanium is the way to go. Even changed all my bolts to titanium. Also, 3M makes a thin clear film used on car to prevent scratches. It's great on the top tube and the chainstay to keep them clean and shinny.
CJ
CJ
03-18-14, 12:26 PM
#47
Senior Member
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Like stainless steel, titanium does not have a very good wearing surface and tends to gall as a fastner if too much force and speed are applied. Mixing the material, SS on steel or Ti on steel is ok.
03-18-14, 02:47 PM
#48
Junior Member
Thread Starter
Join Date: Feb 2014
Location: San Diego, CA
Posts: 90
Bikes: 2017 BMC Road Machine, 2014 Niner Air 9, 2022 Niner RLT, 2020 Niner Jet 9, 1993 Santana Rio, 1996 Santana Sovereign, 1996 Santana Picante,2005 Santana Team Scandium
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Just Talked With Santana
Just got off the phone with Santana, they are going to repair the frame cracks (under warranty) and give me a discounted repaint rate for $250. which I feel is reasonable. I am having them add a disc brake mount to the frame while they are at it for an extra $75. The frame will still be covered under their life time warranty, so if the frame does crack again, you bet I will be pushing for a new one. Oh yeah, updating the steel fork to a carbon one too! Now I just need to figure out what paint color to go with, perhaps pearl white?
Mike
Mike
03-18-14, 03:55 PM
#49
Clipless in Coeur d'Alene
Repair a corroding AL frame? Crazy. Pay for a repaint when they appear to admit it is a warranty issue? Crazy.
You asked for opinions... well, FWIW mine is to not throw more money into this frame. Instead, ask for a significant (and I do mean SIGNIFICANT) discount in a new frame from them. Otherwise walk or run ...
Peace.
You asked for opinions... well, FWIW mine is to not throw more money into this frame. Instead, ask for a significant (and I do mean SIGNIFICANT) discount in a new frame from them. Otherwise walk or run ...
Peace.
Last edited by twocicle; 03-18-14 at 04:27 PM.
03-18-14, 04:35 PM
#50
TKramer
Join Date: Aug 2012
Location: San Diego
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Bikes: Paketa V2r, Co-motion Equator Co-pilot, Bingham BUILT. tandem
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They are only "discounting" the repaint because they don't have to bead blast off any original coating. They'll simply surface prep, prime and paint over the anodized finish.