If you ask me, the most significant part of a bicycle would be the frame. Everything else is just accessories. And one thing that determines the frame quality is the bicycle frame tube thickness.
It needs to be just the right size otherwise, it can feel too weak or too heavy. Neither of them is good. But I think it’s better to have a heavier sturdy bike frame rather than a lightweight weak bike frame.
In most cases, beginners can’t figure out which tube thickness their bikes should have. But you also have to take the frame material into account. For the same thickness, a steel frame will provide much better weight support than an aluminum frame.
We have many things to talk about. Let’s discuss.
Bike Frame Tubing — What to Know About It
The crucial part a frame plays in a bike’s performance, and durability is determined by two things — tube diameter and tube wall thickness.
When we say the thickness of the tubing, we mean the wall thickness, whereas the tube diameter can mean the inside and outside diameter.
Both wall thickness and diameter determine how robust the frame will be.
Importance of Frame Tube Diameter
Bicycle frame diameter is measured from the inside and outside. If you take the outside diameter and subtract the wall thickness, you get the inside diameter. But what does it have to do with strength and durability?
We know the thicker a rod is robust, it is against loads. The difference between a tube and a rod is just the hole in the middle. But it carries the same principle.
If you want a stronger bike tube, it needs to have a large outside diameter and a small inside diameter. The smaller the hole diameter is, the more resilient it is against heavy loads.
For example, a bike frame with a 4 cm outside diameter and 2 cm inside diameter is weaker than a tube with a 4 cm outside diameter and 1 cm inside diameter. The latter would be much stiffer and stronger than the former.
Importance of Frame Tube Wall Thickness
While the bike frame tube diameter is important, and even more important factor is the wall thickness. The simple formula is; that the thicker the wall, the better it will support loads.
But there is also the topic of maintaining a manageable weight. A tube with a .5cm wall thickness is certainly stronger than a tube with a .2cm wall thickness. But the former tube will also be much heavier than the tube with a thinner wall.
As you can see, it’s not as easy as picking a tube with a thicker wall and a large outside diameter. You have to take the weight consideration into account.
So how would you find the optimum wall thickness for your bike?
How to Choose the Optimum Wall Thickness and Diameter?
Let’s explain something. A wider tube can be more forgiving about the wall thickness than a narrower tube. The structural strength relies on the amount of material.
Suppose you have two tubes with the same wall thickness but different outside diameters. Which one would be the stronger one?
Yes, it’s the wider one.
The formula goes like this: the tube’s strength increases as the cube of its diameter increase. So, a 4 cm wide tube is 8 times stronger than a 2 cm wide tube. A mere 2 cm can make so much difference.
However, it will also be heavier than the narrower tube. You can cut down the weight by reducing the wall thickness, which will also mean a reduction in its strength.
But you can cut down wall thickness only so much. There’s a limit to it.
So, the trick to choosing the optimum diameter and wall thickness would depend on experiments. Fortunately, users do not have to do it as the manufacturers have found a few optimal measurements that the industry follows currently.
Bike Frame Tube Sizes
- Road bike frame shell width: 68-70mm
- Newer Mountain bike frame shell width: 68-78mm
I think we now have a pretty good idea of why choosing the right bicycle frame tube thickness is important. There are so many things that affect the integrity and structural strength of a bike.
Fortunately for you, the set industry standards are there to make sure users feel right at home riding their bikes. But don’t just emphasize the tube measurements. The material selection is just as important.