# Shibuya DX Plunger Button vs Avalon Classic Button



## MartinOttosson (May 31, 2011)

It looks like basically any budget plunger, just this time in the shape of Shibuya. 
I like the fact that it has a plastic piston/tip however. I always avoid plungers with metal pistons. 
The progressivity of the spring action is what makes the Shibuya good. Not the shape. If this has a linear/even pressure curve, it not going to shoot as well as the original.


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## chase128 (May 29, 2015)

Ok, it makes sense to me that the pressure curve could change arrow flight, but what specific aspect?

Let's say you have two identical plungers otherwise, (let's say two shibuya or beiter) and one has a more linear pressure curve.
If you have the tension setting tuned so that at the same amount of flex on the arrow they have applied the same amount of pressure, why would it cause a noticeable grouping difference? 
If at the same flex point and time, the correct amount of pressure is being applied by either plunger, shouldn't either of them be able to tune a good group?

If I take just the spring from the avalon and put it in the shibuya and re-bareshaft tune, would I get worse groups / more arrow wear? 
Or is it just that the spring will wear out faster because it is applying more pressure earlier?
(^Now I really want to try this as the springs appear compatible)


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## MartinOttosson (May 31, 2011)

There are two things that are really important in a plunger, apart from the obvious that the precision in the mechanics have to be good enough to provide a smooth, reliable action. 

Nr 1 (and also priority 1): The weight of the piston. 
According to my experience, lighter is always better here. It doesn´t matter how good the spring characteristics is if the piston is heavy. The reason is that a heavy piston is too slow to react, both inwards and to return during the extreme short amount of time where it have contact with the arrow. The plunger only have about 3-6 thousands of a second of time to move. The lighter, the piston, the more "pure spring action" you get instead of a dominating moment of inertia from a heavy piston. A lighter piston does not only shoot better. It is also a lot easier to tune, since spring adjustments have a more logical impact on groups and hits when the effect of inertia is reduced. I made some tests once where I compared different pistons from very heavy (added weights) to very light (ultra light modified pistons) and the difference is very clear. Light is good. Heavy is bad. The test was btw made to see if a, back then recently introduced, magnetic plunger with extreme progressivity was good or not. It didn´t work at all, no matter how nice the magnetic action was, and the reason was piston weight. 

Nr 2 (second priority): The spring character. 
In most applications when springs are used, you want a spring with a "linear" behavior. In archery in the shape of a plunger however, you want the opposite which is often called a progressive spring. The term linear is commonly used, but is not really teoretically or mathematically correct. What we mean is that the first mm of compression needs the same amount of force like the last mm of compression, so it´s might be better to call it constant force plunger or whatever, but since linear is well known, I'll stay with that. Progressive means instead that the force needed to compress the spring gets higher and higher the further the compression goes. 

What happens in a shot is that after the release, the arrow bends towards the riser and compress the plunger at one single time. Both the amount of bending and the exact position of the string and shaft varies slightly from shot to shot, depending on shot quality. That variation leads to that the plunger piston is pushed in slightly different from shot to shot, especially if you compare a good and a bad shot. Some shots creates less plunger compression and some shots creates more plunger compression. If you have a progressive spring, it will be more easily compressed until the normal point during shots that pushes less on the plunger, and then it will resist to be compressed any longer than the normal point on shots that pushes more on the plunger. That means that the sideway angle of how the arrow leaves the bow will vary less with a progressive spring character. This leads, ofcourse, to better groups. 


You will be able to tune the bow perfectly with any of the plungers or springs, as long as you shoot (olympic) recurve, and by perfectly mean that the bareshaft hit right in the fletched group. The difference will instead be seen in grouping in the long run. You will, almost surely, shoot slightly more points with the more progressive plunger. The only situation where I prefer a linear and also soft plunger is indoors with really thick and long aluminium arrows. For some reason, I tend to group better with linear plungers then. 

If you shoot WA barebow(stringwalking), however, you will not be able to get a good tune with the linear plunger. You will then get to much variation on short and long distances, because of the different forces delivered into the arrow on different crawls. 

The Shibuya is very good when it comes to not wearing arrows out. Probably the Avalon copy is too. What you should avoid if you worry about arrow wear is fiber reinforced pistons without teflon/brass tips. The springs normally never wears out, even in very low cost plungers. What you could do however, is to put all pistons on a scale and choose the lightest one. That plus the any of the Shibuya springs will most likely be the best best shooting combo, no matter if its the Avalon or the Shibuya parts. 




chase128 said:


> Ok, it makes sense to me that the pressure curve could change arrow flight, but what specific aspect?
> 
> Let's say you have two identical plungers otherwise, (let's say two shibuya or beiter) and one has a more linear pressure curve.
> If you have the tension setting tuned so that at the same amount of flex on the arrow they have applied the same amount of pressure, why would it cause a noticeable grouping difference?
> ...


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## PHo (Jan 15, 2017)

I realize this is an old thread, but is there an update on the comparison between the two plungers?


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## FerrumVeritas (Oct 9, 2020)

PHo said:


> I realize this is an old thread, but is there an update on the comparison between the two plungers?


They look the same, but they don't behave the same at all. The very smooth travel of the piston in the Shibuya, the pressure curve, and the teflon (instead of nylon) are what make it so good. Budget copies lack at least 2 if not all 3 of these characteristics. 
While I have Beiters that I've picked up used and really like the repeatable adjustment, I am confident that the Shibuya can shoot just as well. I don't feel that way about other plungers that I've used and certainly not budget ones.


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## RabbitArcher (Apr 1, 2021)

FerrumVeritas said:


> While I have Beiters that I've picked up used and really like the repeatable adjustment, I am confident that the Shibuya can shoot just as well. I don't feel that way about other plungers that I've used and certainly not budget ones.


I completely agree. My two bows (WinEx riser + Beiter plunger vs. WinEx riser + Shibuya DX) shoot exactly the same. They are both amazing. I also do not recommend budget plungers. I had to purchase the Shibuya plunger in a hurry because my old budget plunger failed right before a competition. Not exactly a pleasant experience.


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## FerrumVeritas (Oct 9, 2020)

I think it’s also worth noting that if you look at the total cost of archery gear, the difference between the Shibuya and a cheap plunger is minimal. Call it $30 tops (and often more like $15). I don’t mean to insult anyone’s financial situation, but that really shouldn’t break the bank when you’re spending hundreds of dollars already.


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## chase128 (May 29, 2015)

Wow, talk about a necropost! A ton of time (over 6 years?!?) shooting and coaching has happened since I originally posted this, but yeah can offer some thoughts and an update.

First, an update about the plunger and it vs Shibuya (I did go on to shoot it with my indoor arrows for a few months to get good testing data)

Would I buy it again or recommend it to someone? 
-No, after being shot a while the action is rough, and the material in the tip makes a screeching noise on carbon when shot with a clicker. It does have a lightweight tip (lighter than the Shib actually), but that's about the only thing going for it

Does it still technically work ok as a plunger? 
- Sure, back as a relative OR novice (I now shoot BB), I was able to match my Shibuya DX personal average and PRs with this at our local state indoor competition. (For reference, at the time my average was about 265 a 300 round). Though, I figure a higher level OR shooter would be able to see a difference in scores more easily. 

If I was equipping a normal student, what plunger would I do?
- If the budget can support it a Shibuya DX, it is rock solid and unbeatable for the price. Even though I shoot Beiters these days on most of my bows, in my opinion the Beiter is still over-priced and over-featured for a beginner. They shoot the same scores IMO, Beiter just has better adjustment options. (And I have tried many lower end plungers and rests from makers like Avalon, WNS, old SF, AAE, Bicaster, clones of high-end, etc) 

And now a few related thoughts after equipping dozens of students a year in the past 6-7 years since my initial post, with us testing a bunch of gear including some budget options.

Firstly, why budget gear and trying $7 plungers? I coach a college club & travel team, where many of the students love coming out to shoot with us and doing local competitions but are working on a shoestring budget. Often our budget from the student is "as cheap as possible to get arrows on paper" as the funding they do have is getting them to the competitions, though we loan them as much gear as we are able. 

Simply, in some cases if I don't provide some cheaper options, people go and buy something even worse (*<- THIS*), or just get priced out of participating. This isn't just about the plungers, this is about increasing value per dollar across all components. For instance; testing what is the best value riser that actually has some room for tiller adjustment (WNS), what cheap backpack won't fall apart flying to nationals (don't buy a Legend Artemis), etc . . .

So I have long been a fan of getting 3rd party / other option gear and testing it side by side with the known good. In some cases (definitely not all) we have been very pleasantly surprised. 
Not in the case of this plunger of course (Shib DX still reigns "best value" supreme), but we have found some great cheaper gear options for other equipment.
(^Our club could compose a epic ballad in support of Skylon arrows at this point, but that's another topic)


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