Bike Theory For Dummies: Flanges

From Rookie’s Keyboard,

Hello, friends

Good news. I have prepared a very special Bike Theory Lesson (BTL) for you. It was inspired by a very nice fixie bike that I saw the other day. 

Honestly, I am not the biggest fixie fan on the planet, but I can’t deny that the owner of that particular unit deserved massive points for color matching and overall style. The frame was some majestic blue, and the hubs were reflective purple. 

It doesn’t sound like the best combination on paper, but trust me – it was glorious. Sadly, I couldn’t take a picture. It passed by me too fast…and my smartphone loads slowly anyway. But I live in a small town and who knows..we may meet again. 

But let’s get back on track. 

That particular fixie had a high-flange front hub – one of the reasons why the color was standing out so much. 

I know that many rookie cyclists can’t tell the difference between high and low-flange hubs. 

Today, we are changing that in ELI5 style:

The flanges of a hub are the parallel rounded ends (collars) to which the spokes of the wheel attach. A high-flange hub has flanges of a larger diameter. A low-flange hub has flanges/collars of a smaller diameter. 

It’s really that simple.

The images below explain the above in more vivid detail. 

High-flange Hub (HFH)
Low-flang Hub (LFB)

So, what are the important properties of high-flange hubs?

  • Lateral Rigidity of The Highest Order

The bracing angle is formed by a line perpendicular to the middle of the hub/axle and the spokes on each side. 

The taller the flange, the larger than angle becomes. A larger angle makes the wheel more resistant to lateral stress. 

That extra stiffness is considered beneficial in the world of track cycling because it minimizes power losses (softness always kills energy transfer). And since track bicycles aren’t designed for comfort, stiffer is always desired.

But if we are talking about daily cycling, ultra-rigid wheels could be uncomfortable to ride, especially if the tires are narrow too (e.g., 25mm or less). 

  • Attractiveness

HF hubs, especially in vivid colors or chrome, are like a gracious ornament on a gazelle. They just stand out and make you look at them. 

And let’s be honest, we all want bikes that have some character to them. We want other cyclists to look at our wheeled pony and nod in agreement…or at least stare with a curious look.

Of course, high-flange hubs look best on slim steel bikes designed for speed on paved roads. 

It’s also not super uncommon to see HF hubs on a BMX, although the practice is getting out of style.

  • More Ground

The large flange provides more space allowing larger gaps between each spoke (extra strength) as well as the use of more spokes (if needed). 

Low Flange Hubs

Low-flange hubs are the current standard and are found on most modern bicycles. 

Their strongest points are:

  • Compliant

The smaller bracing angle (explained above) makes the wheel more compliant (flexible) and results in a softer ride. But, to be honest, fellas, there are far too many factors involved in how a wheel behaves. 

It would be erroneous to conclude that a wheel with a low-flange hub is always more comfortable. Other parameters such as wheel size, tire width, rim material, spokes, and the lacing of the wheel influence ride quality.

  • Lower drag

The more compact profile of the hub and the small bracing angle make the wheel more aerodynamic. I know that most people may not care about this property, but for the sake of details, I will mention it.

  • Availability + Disc Brake Ready

High-flange hubs are difficult to find whereas the low-flange models are available everywhere, and some are compatible with disc brakes. 

There are two main ways to connect a disc rotor to a hub – centerlock (Shimano) and the 6-bolt system. So, if a hub has one of those, it’s compatible with disc brakes. 

What about weight?

As you might guess, when all parameters are equal, high-flange hubs weigh more. The discrepancy varies between 10-40% depending on the manufacturer and the particular model. 

But to be accurate, you will be hard-pressed to find the same hub available in both formats for an accurate comparison to take place. And those 40% may seem like a lot, but when presented in grams they could translate to only 80-100. 

You also have to take into account that high-flange hubs could require slightly shorter spokes, but not as short as one might think. How much shorter depends on the used lacing method. 

If the spokes are radial, then high-flange hubs will require notably shorter spokes. In that case, the shorter spokes will compensate for the extra weight of the hub (not that it matters).

Radial lacing means that the spokes go towards the hub in a straight line, and if their length is projected, they will go through the heart of the hub. The image below makes it all clear and reduces the need for lengthy descriptions.  

Radial Lacing

However, this is not how most wheels are laced. The “cross” method is a lot more common, and in that case, the spokes are tangent to the hub. 

“Tangent” originates from the Latin word “tangere,” which means “to touch.” A tangent is a line that touches a circle at one point on its circumference without entering its interior.

A tangent line/spoke does not pass through the hub if extended and has only a single point of contact with the periphery of the hub. 

The two most common tangent spoke-lacing methods are 4x and 3x. 

In the first case, each spoke crosses 4 spokes on the same side of the hub. As the image below shows. 

And of course, in the 3x case, each spoke crosses 3 spokes on the same side of the hub. 

The green spoke crosses 3 red spokes.

So, what does all of this mean for us, the rookies?

While it’s nice to be familiar with the technical benefits of both hub models, it all comes down the aesthetic preferences. 

Yes, I said it. And that’s the truth. It’s indeed mainly about looks.

Calm down, though, I will tell you my preferred setup for maximum aesthetics and performance.

If you run a low-flange hub on the rear wheel and a high-flange hub on the front, you will get the best of both worlds, at least theoretically.

Most of the stress during standard riding is on the rear wheel as it supports about 70% of the rider’s weight (it depends on the geometry of the frame). Therefore, it makes a lot of sense to use a rear hub that will make the wheel more compliant. 

Also, the rear hub is not on display, especially when the bike has gears, and you won’t be getting style points for it anyway.

Meanwhile, the front hub is always visible (even more so when you have rim brakes) and supports less weight. Thus, it makes sense to put a high-flange hub on it, preferably in a nice color. 

But as I’ve already said in many other posts, all that matters is to go out and ride.

Don’t obsess. 

Just ride, brother. 

Until next time,

– Rookie






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