Lift XD Speeds

[B-Rock]

Anyone who shoots a Lift XD please post your setup (#, DL, %LO, arrow weight) and chrono’d arrow speeds. I’m shooting WELL under what I should be with my specs and want to see what kind of speeds yall get.

Mine is 75* lb, 80%, 32.5” draw, 431 TOW at 315** fps. System X strings, bow in spec, tuned, timed.

*limb bolts maxed, only pulls 70#, verified on 3 scales.
** Speed verified on 2 chronos

 

[Mighty Mouse]

I don't shoot a Lift XD but your speed is about what I would expect. Mathews claims the Lift XD can reach "speeds up to 363 fps", which I assume they're achieving at 5 gpp (grains of arrow weight per pound of draw weight) with the draw length maxed out at 33.5". Assuming 10 fps loss per inch of draw length reduction, that equates to 353 fps at your DL with a 350 gr arrow at 70#. 350 gr at 353 fps is 96.8 ft-lbs of kinetic energy (KE in ft-lbs = [Arrow Weight in gr] × [Arrow Speed in fps]² ÷ 450,380). Assuming KE remains constant across arrow weights*, you would get 318 fps with a 431 gr arrow (Arrow Speed in fps = SQRT[450,380 × {KE in ft-lbs} ÷ {Arrow Weight in gr}]) .

*KE actually increases slightly with increasing arrow weight, but the increase is negligible for all practical purposes.

 

[ResearchinStuff]

Pretty sure he's way slow, I think you missed the 75# draw. I know there's some technique involved to install gas strings on a Matthews, but I think the symptom is coming in light on draw weight, not being slow while hitting draw weight.

Is your draw weight measured or just going off the mods?

 

[Mighty Mouse]

Pretty sure he's way slow, I think you missed the 75# draw. I know there's some technique involved to install gas strings on a Matthews, but I think the symptom is coming in light on draw weight, not being slow while hitting draw weight.

Is your draw weight measured or just going off the mods?

OP said he's got 75# mods with limb bolts maxed but it's only measuring 70#. I agree he would be slower than expected at 75#, but at 70# his speed looks about right. He probably needs to put some twists in the cables to get DW and ATA into spec.

Mine is 75* lb, 80%, 32.5” draw, 431 TOW at 315** fps. System X strings, bow in spec, tuned, timed.

*limb bolts maxed, only pulls 70#, verified on 3 scales.

 

[B-Rock]

Pretty sure he's way slow, I think you missed the 75# draw. I know there's some technique involved to install gas strings on a Matthews, but I think the symptom is coming in light on draw weight, not being slow while hitting draw weight.

Is your draw weight measured or just going off the mods?

Thanks for the response. Per usual, once I asked for help online I answered my own question. I scoured YT for reviews of the lift XD and comments with other specs. The arrow speed calc below with their specs matched every single one within 1fps. I entered my info and it was within .5fps, wildly impressed.

I think my suspicion came from assuming my actual # matched my mods and while on the phone with Mathews they said IBO was 434 (lift x IBO) lift xd is 334. And that is what I ran my numbers with on the calculators from my original post.

All that said, I think I’m where I should be.

Arrow Speed, KE and Momentum Calculator — The Arrow Builder

Many online arrow/bow speed calculators use an oversimplified calculation to determine arrow launch velocity. This results in inaccurate results, especially at higher grain weights. Increasing arrow mass always will lead to marginal increases in KE, meaning the bow gets more efficient as grain wei

www.thearrowbuilder.com

 

[OR Archer]

The weight on the mods for the Lift XD do not reflect what the bow is making by design. You have the 75# mods but on that particular bow it will be 70#. That’s why their peak weights are advertised as 50-75# and not 55-80# like on the other Mathews. If you truly want 75# you would have to put the 80# mods on it. That is why you are not seeing the speed or poundage you were expecting. Your pro shop should have known and explained the mod weights to you at time of purchase.