I would like please to ask which one is the main differences in playing between bimetal yoyos with side rings and centre rings.
I am not long time into the bimetal world and I can’t deny that from when I am using them I really did understand how much more powerful in every field a bimetal generally is, a very noticeable difference!
Recently I am playing a lot with the Unprld Seiji (side rings) and a full 12 hours with the SU1 (centre rings), I never had a yoyo with centre rings before so this was a completely new feeling for me but very interesting, both yoyos are based on the cognition series so they share some similarities and that’s why I wanted to see if my impressions are fine and use those yoyos as comparison.
While the Seiji seemed more “free” nimble and floaty and you can feel the weight on the sides (like in other yoyos I have for example the Duncan GTR-JS share many similarities with the Seiji) still keeping a great power and stability the SU1 is even more powerful, so fast, the weight is concentrated in the centre of the yoyo or at least is where I can feel the weight, the SU1 seems to follow a “rail” on the string which made it incredibly balanced and very good for tech tricks, I felt like guiding the yoyo between the strings seemed so easy and precise.
The Seiji has a bit more freedom of movement in arm tricks and similar body tricks while the SU1 in horizontal keep a stability that I never have seen before, it just stay there and is so easy to manoeuvre during a zontal combo.
I was wondering if it wasn’t only my impression or other people experience this and also which ones are other main differences between centre and side rims, also because until now I tried only the SU1 with centre rims and also if you want which ones you prefer between the 2 type of rims!
In terms of inertia only the perpendicular distance from the rotation axis is relevant. It does not matter where the mass sits along the axis. So an inside ring with the same diameter and design as an outside rim will give you the exact same inertia.
Marketing may assign magical properties to either ring placements, but aside from aesthetics it‘s snake oil.
However, outside rings can usually access the design areas with the largest diameter and thus making use of the maximum intertia the shape can offer.
Thanks Dominik, so basically the difference in playing I find between the 2 yoyos is only (or mostly) dictated by the different shapes of the 2 yoyos and their weight?
Thanks a lot for this, I got surprised because I never had a yoyo focused on the weight in the centre and also with the rims in the centre so I thought it was an effect of the rims.
The width in those 2 yoyos is very different 46mm the Seiji and 43mm the SU1
What I wonder now is if it’s snake oil the position of the rims, it is not false advertisement to describe them as a big difference? (not UNPRLD but some brands did it in the past and I think you wrote a comment as well in one of the post)
i think the weight pacement (close to bearing gap vs on the rim)
does matter
there is an interesting science video on this The Bizarre Behavior of Rotating Bodies - YouTube
in short, objects that have a higher MOI on one axis but not the other, tend to be more stable, but very widely weighted yoyos (outside normal design params) could be less stable on the throw due to not having a clear primary axis
this is part of why almost all yoyos are thinner than they are tall
it would also explain why W shape yoyos tend to feel more stable feeling than pure V shaped yoyos all things being equal (of course good designs migitage problems and increase the +ve aspects of any shape
