In a previous post, Formula fittings are compared to ILF. In this post, a deeper dive into the Formula limbs.
A 2009 Hoyt product catalog introduced the system
NEW PARALEVER MOUNTING SYSTEM
The Formula limbs innovative, all-new cross-carbon multi-laminates work in concert with the Paralever Mounting System and extended limb design to reshape the limb stress curve for unmatched smoothness before the shot. The Paralever mount also manages vibration after the shot, with more than 40% less limb stress in the critical riser interface area. The result: increased smoothness in the clicker zone and a substantial velocity advantage with ultimate accuracy. The Paralever mount also further reduces limb alignment tolerance, allowing for rock-solid alignment stability and 0.005” increment adjustment capability using the ultra-reliable Hardlock alignment module.
Formula system components feature two riser lengths and three limb lengths for combinations ranging from 66 to 72 inches in length, and from 22 to 50 pounds measured to ATA standards.
The Formula Series Limb Dampening Bushing allows the use of accessories like the FUSE Recurve Shock Rod or even a simple Doinker suppression mount – to absorb vibration before it gets to the riser. This patent-pending feature is exclusive to the Formula Series.
The Formula Patent
A traditional archery bow includes a handle assembly, a bowstring, and at least one connection apparatus. The handle assembly includes a riser, an upper limb, and a lower limb. The upper and lower limbs each include a proximal end connected to the riser and a distal end. The bowstring extends between the distal ends of the upper and lower limbs. The at least one connection apparatus is mounted to at least one of the upper or lower limbs. An accessory such as a bushing or stabilizer may be mounted to one of the limbs with the connection apparatus.
In my view, the two distinct features are:
- Longer fitting compared to the ILF
- Limb dampening bushing
The change in geometry on the Formula limb (about 1.5 inches longer) will change the physics of the limb. The longer working segment of the limb will change the drawing and loading characteristics of the limb. In theory, the total length of the limb could be made lighter since the thick, heavy part of the limb doesn’t have to be as long. Lighter limbs will change the energy dynamics of the bow in general.How would a normal human test this? It would require Hoyt to make identical risers in both the Formula fitting and the ILF (“Grand Prix”) fitting. Then, identical Hoyt limbs in both fittings and an incredibly robotic archer shooting statistically random sessions (hot, tired, indoor, etc). This would be fantastic, but unlikely since Hoyt doesn’t produce their high end risers in both fittings. They do produce the Horizon in both fittings. As a parent of a young archer, I struggle to think about the nearly robotic archer to launch and measure the results.
Limb Dampening Bushing
From Hoyt Patent
This is the second feature of the Formula is the the threaded socket (bushing) to allow a new class of dampener to attach to the limb and absorb vibration from the limb before it hits the riser. The patent illustration shows this example:
From Hoyt Patent
This sounds logical and it would be neat to see innovation in he limb dampening space.
Photo from Bignani Archery (Italy)
And here is an archive picture of Brady Ellison shooting Formula limbs with a dampener.
Photo from Wired Magazine
You can see the dampener highlighted in yellow. There’s a special dampener on the back of the bow shown in blue. I suspect that might be a Doinker.
In 2017, several years after the introduction of the Formula limbs, the market should have many options. Sadly, there are not a lot of market options. Is the market voting that this technology isn’t living up to the promise?
The dampener used by Brady Ellison appears to be a Sims Limb Saver Node. It was released in 2010. According to Lancaster, it has been discontinued.
The FUSE Recurve Shock Rod also appears to be discontinued.
An interesting question remains. If you attach something like the FUSE dampener to your limb, do you only attach it to the bottom limb? Do you shoot with this apparatus on both limbs? Does only the bottom limb produce vibration? I guess the advantage of the riser based stabilizer is that it can take vibrations out from both limbs.
If you are chasing the top of the line riser from Hoyt, it will be a Formula fitting riser. The Hoyt engineering team may have found a way to get straighter and lighter limbs by changing the ILF into the Formula fitting. Any benefit you receive from the Formula fitting will be wrapped up in total engineering of the premier equipment from Hoyt. I don’t think you will be able to say the limbs were the single secret.