From Rookie’s keyboard,
Let’s get to the point.
Hi-Ten steel frames should be avoided at all cost. And that’s coming from me – a cyclist who’s big fan of steel.
The three main reasons are:
- They’re heavy and weak.
- They’re heavy and weak.
- They’re heavy and weak.
Did I say that they’re heavy and weak?
The term Hi-Ten steel stands for high-tensile steel.
Tensile strength is a measurement of how much pulling a material can withstand before deforming, breaking, or tearing. Even though Hi-Ten steel is marketed as a strong material, its tensile strength is not as high as one might think.
- The tensile strength of Hi-Ten 1020 Steel (the most common type used for bicycle frames and forks) is 420 MPa or 60900 PSI.
- Meanwhile, the tensile strength of 4130 Steel Cr-Mo is 670 MPa/97200 PSI.
That’s 37.4% more than what Hi-Ten steel offers.
The discrepancy creates the following issue.
If a hi-ten steel frame has to match the strength of a Cr-Mo frame of the same size, the builder will have to use thicker and consequently heavier tubing.
I am not a weight weenie myself, but even I can’t close my eyes to the difference because it’s substantial.
When I was a kid, I had the pleasure of riding my sister’s MTB – a cheapo 26-er going under the name Cross Vendetta. The bike was as entry-level as it gets and had a Hi-Ten steel frame that felt heavier than a loaded barbell.
Sure, I was a weak teen, but the heaviness of that bike formed a core memory in my brain. Nonetheless, I used it to deliver newspapers in the local neighborhood when I was 16. I digress.
The point is that the low tensile strength of Hi-ten steel offers two lose-lose possibilities:
Option 1: Strong + Heavy
Option 2: Light + Weak
If you study the market and compare Hi-ten and Cr-Mo frames, you may be surprised how many Hi-ten steel frames weigh about as much as the Chromoly models.
Don’t get excited. The light weight comes at a price – they’re a lot weaker.
The reality is that it’s all about marketing at the expense of strength. As Cr-Mo frames gained popularity, Hi-ten frames started to get lighter and consequently weaker too.
The aftermath?
After a pile of broken/bent/totaled frames accumulated, new Hi-Ten frames were naturally labeled as “pot metal”.
For reference, the old-school Hi-Ten steel BMX bikes were strong but often reached weights around 35-38lbs/16-17kg.
At the same time, Chromoly frames weigh about 23-27lbs/10.5-12.2kg (a 30% difference).
In short, when a Hi-Ten steel frame is made 30% lighter to match the weight of a CR-Mo model, it immediately becomes at least 30% weaker than its “ancestors”.
Hi-Ten Steel Frames Are Stiffer Than Concrete
If you’ve ever ridden a Hi-Ten bike, you will immediately notice that the frame feels too stiff despite being made out of steel – an otherwise compliant/flexy/springy/comfortable material.
Why is that?
Once again, it comes down to the lack of strength.
Hi-Ten steel has a lower modus of elasticity than Cr-Mo. The term modus of elasticity indicates the effort needed to bend a material.
Logically, one can conclude that if Hi-Ten steel has a lower modus of elasticity, it should be more flexible.
Well, the equation is more complicated.
Since the Hi-Ten steel frames are weaker, they cannot be “butted” like Cr-Mo models.
Butting is a process during which manufacturers remove material from parts of the frame that aren’t extremely stressed and add material to the more critical points. The result is a stronger but also more compliant frame.
The strength of Cr-Mo frames makes it possible to use “aggressive” butting; the weakness of Hi-Ten frames prevents that process.
So, ultimately, Cr-Mo frames end up being more compliant than Hi-ten rivals despite having a higher modus of elasticity.
I’m sorry, but Hi-Ten loses another round.
Mixed Frames Suck Too (100% not sorry)
Some BMX frames contain both materials – Cr-Mo and Hi-Ten. The goal is to improve the frame’s strength via the Cr-Mo parts (e.g., the front triangle) but also keep the unit affordable by using Hi-Ten for the remaining sections.
In practice, that strategy sucks for 2 reasons:
- Welding different alloys creates more opportunities for errors.
- The frame is still not as strong as possible while being relatively expensive.
So, in the end, you get a pricey frame without the strength.
Another hard pill to swallow is this:
An event that would badly damage a full Hi-Ten frame will do about the same to a mixed one.
So, why bother, brother?
Cr-Mo Frames Could Be Very Cheap
If you’re planning to buy a vintage MTB or road bike, don’t even look at Hi-Ten frames. Seriously.
You can EASILY acquire a Cr-Mo frame for both types on the second-hand market. In some cases, you may even get an entire bike for a few bucks.
I got my retro road bike (Centurion Futura) with Cr-Mo tubing for 100 bucks. I’ve also bought a retro MTB with Cr-Mo tubing for 30 bucks.
At those prices, one would be a fool to even think of purchasing anything Hi-Ten.
As far as BMX bikes are concerned, things get more complicated because many of the Cr-Mo frames on the second-hand market (at least where I live) come in small quantities, cost a lot and are abused to no end.
Thus, it’s often better to buy new.
Yes, it will cost you a lot more than a Hi-Ten unit, but at least you have the peace of mind that your frame is less likely to disintegrate under you (nothing is 100% certain).
But I don’t have the money…
I get it.
If you don’t have the money, but you are serious about riding BMX, save.
Get another part-time job. Drive an Uber (if that’s an option). Save your lunch money…
Find a way.
I don’t want to sound like your math teacher, but that’s my advice, nonetheless.
Hi-Ten frames aren’t that cheap and suck on multiple levels. So, save, save.
I am not the richest person in the world either. In fact, I lost my job six months ago, my girlfriend left me a few days before this post, but I still wouldn’t buy a Hi-Ten frame as it has all the downsides of steel and none of the benefits.
There you have it, my friends.
Never forget that Steel is Reel…apart from Hi-Ten, of course.
Until next time
– rookie
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