When you want to buy a recurve bow, there is one important decision you have to make: ‘’do I buy a Formula or ILF bow’’. You should take this decision very carefully since you can’t attach ILF limbs to a Formula bow and vice versa. Therefore you are getting locked in the particular fitting you choose. If you want to switch between these two fittings, you will have to buy a complete new bow.
Most archers know that these two limb fittings aren’t cross compatible, but most archers don’t know the pros and cons of both fittings. The fittings are very similar, the Formula fitting looks just like a stretched out ILF fitting. So what’s the actual difference?
Formula and ILF are mechanically very similar. The major difference is compatibility; ILF is widely used by almost all manufacturers, while formula is mostly supported by Hoyt. ILF limbs are available in a large price range, from cheap to expensive. Formula limbs, on the other hand, tend to be more expensive
This answer is a bit simplified though, therefore if you want to know the full story and get some advice, keep reading! I will first explain the idea behind both fittings. Next up I will discuss some benefits of formula. At the end of this article, I will discuss my experience with both fittings and give advice on what I should choose.
The idea behind these limb fittings
To explain the difference between ILF and Formula, we need to dive into the history of both fittings. The fitting we now know as ILF was first introduced by Hoyt in the 1980. Originally the ILF fitting was introduced as the Excel fitting, since the entire Excel line was equipped with this fitting.
The fitting was very popular, because it was very easy to add limbs, and you could adjust the tiller and center shot. Before this fitting was introduced every bow manufacturer had their own proprietary limb fitting. Therefore it was impossible to assemble a bow with limbs and a riser from different manufacturers.
Since Hoyt was and still is the leading brand in target archery, most manufacturers switched to the Grand Prix fitting. Since more and more manufacturers used the fitting, most archers started to call it the International Limb Fitting (ILF).
In 2009 Hoyt introduced the Formula fitting, although the fitting is very similar, they claim that you can shoot more accurate with it. Since 2009 only a few manufacturers have adopted the Formula fitting and in general most Formula limbs and risers tend to be very expensive.
So what are the differences?
We now know that Hoyt introduced both the ILF and the Formula fitting, but what is the big difference? Well there are two distinct mechanical differences, the limb fitting is longer and it features a bushing to attach a dampener. According to Hoyt these features offer more stability because the longer limb has a different stress curve. Also the dampeners allow you to additionally dampen any vibration. In general these differences don’t really make a big difference. In the Olympic Games archers shoot with both Formula and ILF limbs and there doesn’t seem to be a significant difference.
There is one significant difference, between ILF and Formula and that is compatibility. Since so many manufacturers adopted the ILF fitting you have hundreds of choices of limbs. Therefore you can mix and match risers from different manufacturers. Since so many manufacturers have adopted this fitting, you can get really cheap limbs, but also very expensive. Therefore, cheap beginner limbs and expensive professional limbs can both be purchased with an ILF fitting. Sadly this isn’t the case for the Formula fitting, since the fitting is mostly used by archers with deep pockets; there are no cheap options available. Therefore most beginning archers start with an ILF bow.
Just for clarification: this is a joke. The one on the right is a real ILF fitting, but since the Formula fitting is so similar to ILF, you would almost say that it's just a stretched ILF fitting.
Why Hoyt introduced Formula
So, why did Hoyt introduce the Formula fitting? Before I will turn to speculation, let me first discuss the reasons Hoyt gave for introducing Formula.
Different stress curve
When the bow is at full draw, the bow limbs are under a lot of tension. Modern recurve bows are made to optimally distribute this strain, but there are still weak spots. When a bow breaks, it is rarely at point or near the riser; it is most often right in the middle of the limb. This section is most vulnerable for breaking, because it bends the most; this is called the stress curve.
By extending the limb design Hoyt claims that they flatten the stress curve thereby removing vibration. They also claim that they can make lighter limbs because the material has to be less thick. I won’t go into the details of these claims, but in general I don’t think they are a huge difference.
In archery we obsess about vibration, because it makes your shots less accurate. Dampeners are one way to combat vibration, which are often used in combination with stabilizers. If you want to know more about stabilizers, dampeners and vibration in archery, I would recommend reading the following article: ‘’Stabilizers – how they work and what to buy’’
According to Hoyt having dampeners directly on your limbs directly removes additional vibration. I see how that might be the case, but these dampeners do not help decrease vibration before the shot, but only after the shot. The goal of these dampeners is to increase the lifespan of your bow and not to improve your accuracy, therefore these devices are often called ‘’limb savers’’. Removing vibration after your release doesn’t improve your accuracy, but it does reduce the strain on your bow.
Archers often see this as a new feature in the Formula lineup, but actually the bushing is just moved from the riser to the limb. Almost all ILF risers have a bushings which allow you to add an upper and lower stabilizer or two dampeners. The formula risers on the other hand don’t have these bushings, because the extended limb already takes up a large part of the riser, therefore there is simply no space for them.
I am not going into the details on what is better, having the bushings on the riser or on the limb, because I simply don’t know. But you should know, that also most ILF limbs allow you to attach upper/lower stabilizers and dampeners. The bushings are only at a different location.
The real reason
You probably noticed that I am quite skeptical on these reasons; Hoyt claims to introduce the Formula fitting. I like innovation in general; it keeps the sport modern and helps us shoot better. But I think these changes aren’t really innovations, they are just changes to the fitting, without any major change in the technology.
I am quite certain the Formula fitting was just the work of smart marketers. We know Hoyt has a very good marketing department, if you look at their website and marketing materials, you can see that they know what they’re doing. By introducing the Formula fitting in the premium line of Hoyt, they lock people into Hoyt equipment. If you ever want to change your limbs, you have little choice but Hoyt. It’s just like how Apple keeps introducing new charging ports to get more people to buy new expensive cables.
I know some people will disagree with me since a lot of people really like Hoyt. To be honest, I also like Hoyt, they sell really nice equipment and their products always look superb. But the Formula fitting is not the work of years of innovation or anything, it’s just a marketing gimmick, in my opinion.
Since I have both owned a Formula and multiple ILF bows, I would like to share my experience. Many archers claim that Formula equipment has a smoother draw and shoots more accurate. Indeed the Formula Carbon Quattro limbs have one of the smoothest draw I have ever felt. These limbs cost around $600 new, so for a solid comparison you should compare it to ILF limbs of a similar price point. If you compare these limbs to similar priced ILF limbs, you will notice very little difference; both will have a very smooth draw.
The problem is that many archers are comparing the expensive Formula limbs to cheaper ILF limbs, and yes than you will feel that Formula limbs have a smoother draw. This is just why many people claim that Iphones are faster than Android phones, because they compare a $700 Iphone with a $200 Android phone. If you choose two products of a similar price point, this big difference in performance will disappear.
This doesn’t mean that Formula bows are crap and that you should never buy one. It just means that you shouldn’t buy a Formula bow, because you believe it will perform better, that is just not the case. If you really want the top of the line Hoyt bow, go ahead and buy a Formula bow, it’s just a matter of personal preference.
Which I would choose
If you carefully read my article you probably already know my answer, in most cases I would recommend an ILF bow. I started with an ILF bow and I switched my limbs a few time to increase the draw weight. A fellow archer from my local club, offered me to sell him his bow, with Formula Carbon Quattro limbs. I really liked how the bow felt and compared to my cheaper bow, the draw was way smoother. Therefore I decided to buy this bow.
After I while I wanted to change the limbs, since I was so used to ILF I thought I could get a pair of inexpensive limbs, but I was horribly wrong. The cheapest limbs I could get at that time were? $350 and that wasn’t worth it for me at that time. Therefore I switched back to my old ILF bow and bought better limbs for it.
The moral of the story is, if you want to buy a Formula bow, be prepared to commit this bow fully to the Hoyt. One archer on the forum ArcheryTalk fittingly described it:
‘’There is no difference between ILF and Formula, except compatibility, which means that you in essence married to Hoyt’’
So if you want to use Hoyt equipment anyway, go ahead and buy a Formula bow!
Buying new limbs
If you want to buy a new bow or a new set of limbs, I would recommend reading the article below. In that article, I will discuss in detail what you should consider when buying limbs.