From Rookie’s keyboard

Hello, friends

Today, we are going to talk about curved and straight bicycle forks. I will try to provide you with the most comprehensive comparison of those two “monsters” that you can find online. 

And by the end of it, you will know why I prefer the curved version. 

So, fellas, let’s begin.

Curved Forks Are The Bomb For Custom Frame Builders

The largest advantage of curved bicycle forks is that their offset comes from the curve and can be added later. 

I fully realize that the above sentence is not the most “rookie-friendly”, but don’t worry…it will all make sense in a second. 

The fork offset a.k.a. fork rake is the perpendicular distance between the steering axis and the front axle (the center of the front wheel).

In the graph below, the fork offset is in blue. 

The fork offset influences the bike’s behavior. For instance, a longer offset increases the bike’s wheelbase (the distance between the two axles/wheels) and thus increases stability at the expense of less agile steering.

Obviously, reducing the offset would have the opposite effect – decreased bike stability but more sharp steering. 

The curved variant is a lot more flexible because a builder can keep a large stack of forks with non-bent legs and bend them according to the desired geometry later on. Meanwhile, the offset of the forks with straight blades is already preset and cannot be changed later to suit the plans of the builder. 

Another advantage of curved blades is that they have a slight suspension effect. This effect is amplified by the fact that curved forks tend to be made of steel – a compliant/flexible material.

This doesn’t mean that a straight fork is always harsher…but it usually is…unless it’s made out of carbon. I am not a fan of carbon forks as I consider them too “spoiled” for rigorous riding. 

The cheaper straight forks are made of aluminum – a non-compliant material. That said, one should also take into consideration the tires as they provide a lot more suspension than a rigid fork. 

If the tires are fairly wide (28mm or more), then they will support a low enough air pressure to make up for the harshness of a straight aluminum fork.

Traditional Aesthetics. The final advantage of curved forks that I’d like to point out is that curved forks just look right on classic/vintage bicycles. A straight fork on a similar machine is simply out of place.

The Advantages of a Straight Forks

I am not a fan of straight forks for 2 reasons:

• They don’t have a traditional look.
• They are harsh unless you go for carbon, and I don’t like carbon

But this article will not be complete if I don’t list their strong sides, namely: 

• Easier to Produce Out of Carbon

Carbon straight-blade forks have a simpler shape and are therefore easier to mass produce. Meanwhile, curved carbon forks are a rarity because carbon can get “wrinkles” if molded into a curve. 

So, the financial incentive just isn’t there as the extra quality control and production steps will not be justified in the end. After all, 99% of consumers out there care primarily about the price and the material rather than the shape of their forks.

• Lighter

As a genius would say – the shortest distance between two points is a straight line. In other words, a straight-blade fork requires less material than one with curved blades. Therefore, when all other parameters are equal, a straight fork should weigh less. But to be honest, the difference is negligible. 

• Disc-brakes Ready

Caliper disc brake mounts are a lot more common on straight-blade forks.

• Updated Design

Straight-blade forks look up-to-date- when installed on a modern aluminum or carbon frame. 

So, what should you choose?

The most important part is understanding that the fork’s offset impacts handling. And if you want to preserve the way your bike operates currently, you need a fork with a similar offset to the original one. 

Only then does the shape of the fork come into play. 

Of course, some people may wrongfully conclude that curved forks always have a greater offset and while that’s often the case, it’s not 100% guaranteed. 

How so? 

Well, the offset of a straight-bladed fork comes from the angle between the steerer and the crown and can match that of a curved fork. 

The genius image below explains that exceptionally well. 

If a curved-bladed and a straight-bladed fork have the same offset, then the material comes into play. As mentioned, I’d stay away from aluminum forks with straight blades unless the tires are at least 28mm. If you have a rigid MTB or a gravel bike with some 40mm tires, then it doesn’t matter all that much.

If you’re running a road machine with thin tires (25mm or less), then a carbon straight-blade fork or a steel curved fork would be the logical options for their compliance. 

I’d goal with the steel as I am not the biggest carbon fan primarily due to its looks and lack of toughness on impact. 

The Axle-To-Crown Lengh Is Also Important

To fully preserve the original handling of your bike, you will also have to match the axle-to-crown length (ACL) of the potentially new fork and the old one. 

The ACL is the distance between the front axle of the wheel and the fork’s crown.

If the new fork has a longer ACL, the front end will get higher. Or in more complicated words, the head tube angle of the bike will get slacker and some of the rider’s weight will shift to the back.

A slacker head tube angle will make descents slightly easier because the front wheel is further in front of the rider and can “eat” the irregularities. The downside is decreased control at slow speeds and more difficult climbing due to weight shifting to the rear. 

A fork with a shorter-than-needed ACL will have the opposite effect – a steeped head tube angle making climbing easier and descending more dangerous due to the greater chance of flipping over the handlebars. 

And there you have it friends,

Another article that should make biking dilemmas slightly easier to solve. 

Until next time, 

– Rookie