Yo-yo science experiment challenge: how much does your string stretch in play?

(Thomas Bellotti) #24

Wow that’s super cool of you to do, dude.

And good job on the experiment. The question was an interesting one I hadn’t even considered.

I’ve never seen something so awesome on any forum/message board. Quite the opposite usually haha. Seriously though, this place is awesome. Just discovered yoyos a little over a week ago, already own four (n12,purple line, node, and my favorite-my SHUTTER) and instantly understood the pictures of massive collections on here.

This community is great, and I’m loving the hobby too

TLDR: You people are cool people

(ChrisFrancz) #25

Don’t be a stranger - when not throwing, read, like, reply, repeat,

(Thomas Bellotti) #26

Hey thanks dude. I’ll try to remember to chime in once in a while, though I’m usually a chronic lurker.

I’ll be reading as much as possible, because I know next to nothing, and fortunately this place seems surprisingly active.

Thanks for the welcome


Nobody wants to do any STRING SCIENCE for a free, mint Shutter? Let me post a pic of the goods to encourage more SCIENCE!

(Justin ) #28

I totally forgot about this! I’m definitely making a post soon :wink:

(Mk1 Yoyos) #29

Starting my experiment today. Two prestretched, two regular, and I discovered I can’t tie knots accurately. All strings are 1/3 nylon, 2/3 poly.

(⛷ Noisy Lurker) #30

Type 6, type 8, poly, cotton, purchased, home brew? Same yo, different yo, weight of yoyo, humidity, time left unwound from yo before comparing, molecular structure, microscopic differences and color v.s. uncolored; DUDE I’M NOT GOIN BACK TO SCHOOL! So just shutter me out!

Let’s face it, you’re not stringing me along! I just can’t be stretched like that.

(Justin ) #31

I’ve completely my personal experiment! Here’s the rundown:

I tested the stretch of three different strings: YYSL Ammo, Kitty Fat, and Kitty Nylon (Fat). YYSL Ammo was used with my SF L (a very not good idea, I forgot that Ammo is thicc), Kitty Fat was used on my Unparalleled Abuction, and Kitty Nylon was used on an old YYF CZM8.

Some Notes:

  • I started the started the strings at the 1 inch mark on the tape measure for accuracy, so subtract 1 from any length you see in pictures.
  • The order of individual pictures will always be Ammo, Kitty Fat, Kitty Nylon.
  • I played with each yoyo for at least 3 hours. I got pretty close to my changing point for my Kitty strings, so I feel like this was a good stopping point, when taking into account the lifetime of the string.
  • Results may vary!! Measuring new string without stretching can be relatively inconsistent.
  • The results section will be separated into three categories: Raw, Looped, and Stretched. The Raw section measures the string before the loop is tied. The Looped section measured the looped string. The Stretched section measured the played string.
  • For the Looped and the Stretched sections, I am measuring from the bottom of the string to the bottom of the tied loop.
  • There will be a final table at the bottom for a concise data display.



As you will see in the following photos, the string is not completely straight, so I am including an uncertainty of ± 0.25 inches for each measurement.

  • Ammo = 45.5 ± 0.25 inches
  • Kitty Fat = 50.25 ± 0.25 inches
  • Kitty Nylon = 50.25 ± 0.25 inches


The looped string was stretched a bit, as I had to tie the loop tight. I am however keeping the same uncertainty, as I feel the amount I stretched the string while tying to be negligible.

  • Ammo = 42.5 ± 0.25 inches
  • Kitty Fat = 43.25 ± 0.25 inches
  • Kitty Nylon = 42.85 ± 0.25 inches


The string has stretched significantly, so I am reducing the uncertainty to ± 0.1 inches.

  • Ammo = 45.8 ± 0.1 inches
  • Kitty Fat = 46.25 ± 0.1 inches
  • Kitty Nylon = 45.55 ± 0.1 inches

Data (in inches):

Raw Looped Stretched Δlength
Ammo 45.5 42.5 45.8 3.3
Kitty Fat 50.25 43.25 46.25 3
Kitty Nylon 50.25 42.85 45.55 2.7


My data definitely lines up with my observations during play. As the hours progressed, I noticed that the Ammo string was the most bouncy, and the Nylon the least, which would likely translate into their respective ability to stretch. I suggest you all to also try this to see what you guys get and how it differs! Also, I think the best follow-up to this experiment is to see if stretching the string beforehand will prevent the string from stretching any more during play! The end goal of course is to find the best way to keep your string length as consistent as possible. I’m curious if string tension has anything to do with stretch. Maybe a string that comes less tightly wound will not stretch as much?

Thanks for your time guys! I hope this isn’t too long.

TL;DR String stretched about 3 inches. Out of Ammo, Kitty Fat, and Kitty Nylon, Nylon stretched the least and Ammo the most.


Awesome! :clap::clap::clap:

I got a little confused when you said looped, I thought you meant you used it in a looping yo-yo :grin:

I am curious, can you do a quick follow up… wouldn’t throwing stretch the string way more than simply pulling on it with your hands? Maybe you could do a quick test, see how much you can stretch a string with your bare hands. My theory is, it won’t be near as much as actual play stretches it…

(Justin ) #33

Should I try and stretch the string out as much as possible?


Sure take one of those three string types and see how much it stretches from your “normal” stretching regimen with bare hands. I do not pre-stretch any of my strings… is that a thing one should do??

(Justin ) #35

Alright. I pulled out a fresh Ammo string and vigorously hand-stretched it for about a minute.

Pre-stretch on top, post-stretch on bottom:

Almost the same result as my experiment! This is the major benefit of pre-stretching the string. You force all of the stretch out of the yoyo string so you can have a more consistent string length if you care about that.

Here’s Brandon Vu also recommending that you stretch your string for consistent length. (Around 3:13)


I did a quick experiment using only hand stretching

Left to right:

  • Dark = YYSL Type X
  • Lemon/Lime - YYSL Plutonium (fatter)
  • Blue - YYSL AMMO (fattest)

Before hand stretching

After hand stretching

Let’s see…

  • Type X – ~7cm → 12cm
  • Plutonium – 11cm → 14cm
  • Ammo – 8cm → 11cm

So 5cm, 3cm, and 3cm of stretch respectively?

I found a good technique is to put the measuring tape on a doorframe and extend it to the floor… then use a piece of tape to get all the strings at the same height at the top of the doorframe, like so, and let gravity pull the strings straight.

That said, I did mess up a few things here, and I’ll improve on if I try this again:

  • the end knot that I was using to line things up came out of the blue ammo string (!) so I couldn’t put the knot back exactly where it was for the stretched version.
  • gravity isn’t quite as effective as I would like to pull the strings to full length, there’s some wiggle in the strings.

I do like hanging everything on the doorframe though and using the tape to line up the knots!


Brandon Vu did something similar… go from 2:20


Yes that was already linked above! It was just a plain link though so hard to see.

Closeup of his post stretching results. He puts new string on the same yo-yo with the old string still on it (!) so he can do a direct comparison of old (stretched from play) and brand new strings:


the tied bit is his old string, he marked the new string at the very same length immediately after putting it on, so between that and the blue mark is how much it stretched. He calls it 3cm which is definitely about what I saw in my results, but I think it’s a bit more after real play.

(Justin Thompson) #39

So is that all for the Shutter Science? And good job guys, Im definately stretching my strings before play from here on out.


so… you don’t want a shutter? ill take it for you! just kidding, i wont deprive you

(Justin Thompson) #41

Oh no, I’d graciously accept a Shutter. Hence the question.




We still need to hear @markd’s results. If you want to string science, go for it! The more science the better!