Turning up your limb weight

Turning up your limb weight

The modern Olympic recurve bow uses a system for attaching the limbs to the riser called the International Limb Fitting (ILF) system. Hoyt designed this system in the 1980’s (Hoyt now call this the “Grand Prix” system) and have since evolved and developed a new system call Formula. The two systems, ILF/Grand Prix and Formula are not interchangeable so be careful when you’re choosing risers and limbs, make sure they use the same system…

Both systems do however allow for limb weight adjustment. When referring to limb weight we’re not referring to the physical weight but rather the draw weight of the limbs.

The limb bolts on the riser, where the limbs attach to the riser, are used to adjust the limb weight either up or down. Turning the limb bolts in will increase the limb weight and turning the limb bolts out will lessen the limb weight but be careful not to turn the limb bolts out too far, always leave enough threads turned in to ensure the bolt cannot slip out. In general, you should not adjust the limb bolts with the bow strung, there is significant stress and pressure on the limbs and limb bolts while the bow is strung.

The short version.
To adjust the limb weight you would turn both top and bottom limb bolts the same amount and the same direction (in/out).

Okay, don’t panic, it’s not really so bad…
The sentence above is the simple version, but there is something you need to be aware of and take into account when adjusting your limb bolts and that is the tiller.

The tiller is the sum of the upper tiller minus the lower tiller (see the diagram above). You don’t want a negative tiller (lower tiller greater than the upper tiller). Some archers set a zero tiller but the “norm” is a positive tiller but don’t exceed 5mm. The upper and lower tiller is measured from where the limb meets the riser out to the string, perpendicular to the string.

The longer version…
Before you adjust the limb bolts, string your bow and measure and make a note of the tiller and brace height (the brace height is the distance from the throat of the grip to the string).
Then unstring your bow and loosen the limb bolt locking bolts on the reverse side while holding the allen key in the limb bolt, to prevent the limb bolt turning while loosening the locking bolt. Turn the limb bolt a set amount in increments of quarter, half, three-quarter or full turns. Lightly tight the locking bolt, again while holding the allen key in the limb bolt.
Now repeat the same process on the other limb bolt ensuring you turn it the same direction and amount as you did on the first limb bolt. Lightly tight the locking bolt.
Now restring your bow and check the brace height, adjusting if necessary. When your brace height is as it should be then measure the tiller. If the tiller is not within the acceptable range, or it’s negative, then you’ll need to adjust either top or bottom limb bolts, possibly only a small amount.
Turning the limb bolt in (tightening) will bring the string closer to the riser and turning the limb bolts out (loosening) will move the string away from the riser.
Once your tiller is set correctly, unstring your bow and tighten up the locking bolts, while holding the allen key in the limb bolt.

Comments are closed.