MILD STEEL, CHROME-MOLY STEEL, OR ALUMINUM

As with nearly everything one could mention there is good and bad aspects of the various materials available to use to fabricate a tadpole trike. I am only going to talk about the three most common …. mild steel, chrome-moly steel, and aluminum. I am not considering carbon fiber or titanium since they are not very common and are expensive.

Mild Steel — Two things immediately come to mind when talking about a trike made of mild steel —  inexpensive and heavy. Perhaps a third thing pops into my thinking … entry level trikes such as … well, I guess I better not name names here. Most trikes are made of either chrome-moly or aluminum. There is nothing wrong with mild steel construction. It is strong (although not as strong as chrome-moly steel) and has some give and take to it which is good. By that I mean it offers some flexibility vs. being stiff and unforgiving. This makes for a better ride than material which is stiff and non-flexible. It is cheapest and easiest to weld and can be re-welded if it breaks. Mild steel can/will rust if exposed. Most people don’t want the extra weight involved so they stay away from mild steel. Besides most trikes made of mild steel come with lower quality components. Like I said, most are considered “entry level” trikes. A tadpole trike made of mild steel is generally about 7 to 10 pounds heavier than one made of chrome-moly steel or aluminum (although they can be heavier).

I want to insert something here: Please do not misunderstand me. There is nothing wrong with a mild steel trike. However, they are not generally as popular as chrome-moly or aluminum. Those who manufacture trikes realize this and so the trikes they offer made of mild steel are lower cost trikes. To keep the cost down and sell them they obviously can’t and don’t use as high of quality components as higher priced trikes. It doesn’t mean that there is anything wrong with them. It simply means that the old adage holds true … you generally get what you pay for. If you want the best components on a trike you will pay more for them. Again, it doe not mean that the components used on a trike made of mild steel won’t provide years of good dependable service. Originally the Catrike Trail trike came with lower quality components than what Catrike installs on this model now. Of course, the price of the trike was a lot less back then than what it is today. I have replaced all of the lower quality components with much higher quality ones since I bought it. Of course, in doing so I  have spent a lot more money than what the original trike cost which came equipped with lower quality components. It was well worth the cost involved to upgrade to better components.

Chrome-Moly Steel — a very good choice as it is nearly as light as aluminum and is stronger. It also flexes some so provides a good ride. It is more expensive than mild steel and more expensive to weld. Welding chrome-moly steel is a specialty and can only be successfully done by a qualified weldor using special welding equipment. Chrome-moly steel can rust although not as badly as mild steel. Also the rust is usually only surface rust.

Aluminum — the lightest of the three metals and most expensive. Like chrome-moly aluminum is also a specialty when it comes to welding. Aluminum is somewhat stiffer than the other two metals meaning that the ride will be slightly harsher. Aluminum is one material that dare not flex like the mild steel and chrome-moly steel. If it were to flex it would shorten its life considerably. As far as frame repairing goes, aluminum is not very repairable. After it’s welded, an aluminum frame must be heat treated. Once it’s been heat treated, further structural welding will weaken the frame. Sometimes very small things can be fixed, but if something crucial breaks or bends, the frame is done for. I personally would not let this scare me off. If the initial fabrication work was done correctly you should get long service out of an aluminum trike. Catrike is a very high quality trike and made of aluminum. Alize, Catrike, TerraTrike and Sun offer a lifetime warranty on their frames. There may be others but if there are I don’t know of them. Most manufacturers offer warranties of a limited number of years such as 1, 5, 7, 10, etc. The fact that lifetime warranties are offered on aluminum frame trikes speaks of their expected service. Manufacturers would not offer such a warranty if they expected to have to replace a lot of frames.

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Here is an excerpt from a forum on this subject:

“I’m wondering. Is an aluminum frame bound to fail at some time of its life? If well maintained to prevent rust, will steel outlive an AL frame?”

“It depends on the way the frames are made, including the exact steel(s) used [there are many different steels, with widely differing properties, ultimate yield strengths, corrosion resistance, and fatigue limits], the tubing diameters [other things being equal, larger diameters will usually be stiffer and more durable], and the wall thicknesses [very thin-walled steel frames are often not particularly durable].
The same sorts of things can be said for aluminums and various types of aluminum tubing.
Some aluminum frames will far outlast most steel frames.
Some aluminum and steel frames will be about equal in longevity.
Some steel frames will far outlast most aluminum frames.
“Is an aluminum frame bound to fail at some time of its life?”
There are strong, well built aluminum frames that can easily last a lifetime.
Rider weight, strength, and riding style have a lot to do with it.
What causes most frames to fail eventually is repeated high stresses.
A 120-pound rider who has a gentle riding style, and rides on smooth roads, can make a frame last for centuries.
A muscular 240-pound hard-riding athletic type who rides aggressively on steep and rough off-road surfaces and high-speed downhills on a regular basis will destroy most frames, steel or aluminum, in short order.”

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Many homemade trikes are made of mild steel since it is easy and cheap to work with. I made my first tadpole trike and I made it out of mild steel. It was fine, but it most definitely was quite heavy.

Most trikes are made of one of these metals. The better ones are made of either chrome-moly or aluminum. Mild steel just doesn’t seem to be very popular when it comes to tadpole trikes.

As I was reading while writing this article I read on a forum where someone was asking about using JB Weld epoxy on an aluminum bike frame to repair it. I had to laugh although it certainly would not be funny when it failed and something bad resulted. As a professional weldor with over 55 years experience and the highest certification obtainable in manual arc welding (my main interest was always repair welding) I had my own welding business for over 25 years before retiring. Many times customers came to me wanting me to repair weld some item that they had tried to use JB Weld on before bringing it to me. I have used JB Weld myself numerous times. It is a good epoxy but it certainly is not the same as welding and I think they chose a very poor and misleading name for their product which is sad as so many people buy into it thinking it will perform miracles so to speak. The truth is it is about worthless for many of the things people try using it for.

As to the concern over weight … on comparable trikes, one  made of aluminum and the other made of chrome-moly steel, the latter will probably weigh 2 to 3 pounds more than the aluminum one. So it is not a significant amount.

One factor to consider for those who care about such things is that whenever there is flexing there is a loss of efficiency. Whether it be boom flex, seat frame movement or anything else it makes a difference. The less flexing or movement of the frame (including the seat) the more effective pedaling along will be.

Speaking of boom flex this can be quite noticeable in some trikes. Catrike has the best designed boom in the trike industry. They have engineered their boom so that it has very little flex. It has internal reinforcement built into it. It is patented.

Anyone who would like to read more about the metallurgy information click HERE , HERE and HERE. There are many websites one can check out on this subject. HERE are the Google search results for the topic.

metal comparison chart

Truly it is very much a science and many various factors come into play. I mean just how many chuck holes can a trike hit and remain unscathed?

And now for a plug for Catrike —

 my Catrike Trail front view

 I already mentioned making my first tadpole trike and that I made it out of mild steel. I then bought a new Catrike Trail which, of course, is made of aluminum as are all Catrikes. I readily admit that I am prejudice. I don’t think there is a better tadpole trike made than Catrike regardless of the price paid. I know others who have other brands and all I can say is “thank you Catrike” … I prefer mine over any of the other brands. I think Catrike is better engineered and are top quality thru and thru. I am not pleased with some of the decisions at Catrike which have been made in more recent years. I am mainly referring to the fact that the Catrike Trail model is no longer the same trike it was when I bought mine.

catrike trail frame

The frame design has changed from their fabulous one piece simple design (known as “space frame”) to one with an adjustable seat back and a redesigned rear frame all of which adds two more pounds of weight. And now they don[‘t even offer it in anything other than their new folding design which is even heavier and more expensive. It kind of reminds me of the Ford Thunderbird. It started off as a sports car and ended up becoming another Detroit barge. Oh how I wish Catrike still had the trike I originally bought. Well, I guess they are going to do whatever they are going to do. But I sure miss what they first offered as I think it was by far the best design of them all. And not everyone wants or needs a folding trike or an adjustable seat back.

Regardless of which of the materials you select for a trike I hope you enjoy the trike and it serves you well. And may we all …

KEEP ON TRIKIN”

REPAIR WELDING OF A CRACKED ALUMINUM FRAME

fellow tadpole rider I know stopped by my house recently. (His stop had nothing to do with this subject.) While he was here he told me that the frame of his ActionBent trike was broken at the crucifix. He mentioned getting it welded. Being a professional weldor (now retired) I told him that the aluminum frame is heat treated and that complicates things as far as welding it. I cautioned him about not just taking it anywhere to get it welded … that he needs to find someone who is not only very knowledgeable but capable of doing the job right. I want to state upfront that although I am a very good weldor and was highly certified, I make no profession of being very knowledgeable and capable of doing the repair weld on his trike. First of all, I no longer have the welding equipment needed and most certainly I don’t have the means of heat treating the aluminum (nor the knowledge of how to do it). I have welded a lot of aluminum in my life and was certified in aluminum welding, but this is a specialty. I am not familiar with it. And I would think that it is  probably not easy to find someone around who is knowledgeable, qualified and equipped unless one is in the right place such as a large city. I doubt if such a welding business exists around my area. I would rather imagine that going this route is not something usually done. I would think that purchasing a replacement frame is the more common way to go. Of course, some manufacturers offer free replacement under warranty. In the case of ActionBent they are defunct … totally out of business … gone … history. His other option is, of course, buying another trike … which he mentioned. It might be the more practical solution to his dilemma. I know that this problem is not uncommon so I thought I would post this article about it. It also happens with chrome-moly steel frames and mild steel frames although they are much simpler to make welding repairs on. I would highly recommend adding gussets to strengthen the joint where the crack occurred. The manufacturers should have done this to begin with. As a professional weldor and fabricator I would have if I were designing and building a trike.

Here is a picture of a cracked frame right at the edge of the weld on the crucifix:

cracked sun trike frame

It is not something you want to see on your trike. This particular trike is made of chrome-moly steel.

Repair Welding of Heat Treated Aluminum

Some trikes are made from 6061 T-6 aluminum, but the better ones are made from 7005 aircraft grade aluminum. All Catrike frames are made from 7005 aircraft aluminum alloy. All this adds complexity into the picture … knowing what you are dealing with and what needs to be done.

more on welding heat treated aluminum

When my 2009 Catrike Trail frame developed a hairline crack at the edge of the weld on the underside of the crucifix I was concerned as I know it could get worse and in time fail. If they would have put a gusset on the back side of the crucifix like they did on the front side I don’t think this would have ever happened.

cracked frame (weld) 001

So I contacted Catrike knowing that they offered a lifetime warranty on the frame. They readily replaced the frame although certainly not without cost to me much to my disappointment. The “space frame” that I had was no longer made so they sent their new frame. I much prefer what I originally had and wished they would have just taken my frame back and repaired it or replaced it with another one like it, but they don’t offer either so I was stuck with having to deal with the new frame. Although I appreciate Catrike standing behind their product and replacing the frame for me I was not (and am not) pleased with the outcome of not being able to get the same frame I had. Everyday I ride it I wish I had the old space age frame instead of this new design. I just don’t think much of the new design. The space age frame was far superior. Sometimes I regret having the frame replaced under warranty. It is possible that the hair line crack in the weld would have held up fine and given many more years of service. I will never know the answer to that matter. At the very least I could have delayed getting the replacement and kept riding my trike as is hoping for the best. At least up until the time it would fail I would have a superior frame.

Anyway, if you are having or do have this problem of a cracked weld or tubing on your trike keep in mind what you are up against here. If the job is not done right you will probably end up in deep doo doo. Having sudden failure in a weld or frame could be very dangerous. It could happen if the job isn’t done right.

Be safe out there!