The BI Signature Quads lined up to show size difference between fronts & rears.
The main thing that bugged me is that the rear fins have 50/50 foils, which is sort of unusual for a quad setup. One of the appealing things about quads is that the water passing under your tail gets funneled in a dynamic and highly energized manner because of all the empty space under the tail. This type of active water flow causes a lot of lift, extra drive, and creates a natural personality in the tail that reflects the texture of the wave being surfed.
Kinetik Fins come in a nice, heavily padded lunch box style case like this one.
Dims for the BI Quad version: Fronts- 4.37in base x 4.46in height / Rears- 3.89in base x 3.94in height
I also found it kind of irritating, that nowhere on the internet (except here now at TheSurfersView) is the 50/50 foiling of these trailers mentioned. There are a lot of other websites that have reviewed these fins (probably without ever surfing them,) and none of them mention this fairly significant feature at all. (Seriously, there’s actually a video review that goes on for 2 minutes and manages to never say even one word about it. I won’t even link it it’s so lame.)
Another plus though, is that Kinetik’s BI and JP Quads are noticeably tensile for carbon composite fins. This means there’s a nice amount of flex that imitates the bending glidey-ness of traditional fiberglass, but with the snappiness you get from the more rigid carbon composite material. Kinetik’s Carbo Tune technology is a very smart combination of stiff hex and varying degrees of flexible fiberglass.
Dims for the JP Quad version: Fronts: 4.56in base x 4.69in height / Rears- 3.98in base x 4.04in height
Also, the front fins ARE foiled flat on the inside, and they feel very nice in the water. Sharp and very drivey. I’ve tried the BI Carbo Tune Quad fronts with a number of different trailers and a lot of combinations worked well. I especially liked them with Stretch Quad trailers or GX-Q’s (the rears from PC-5’s, PC-3’s, etc…) if you’re looking for that purist quad feeling in the water.
The other thing worth mentioning is that since the BI/JP quad trailers are foiled like center fins, you can totally run this set as a thruster (using the two regular fronts and either one of the trailers as a dedicated center.) This setup works surprisingly well if you like to run a small center on your three fin setups.
Carbo Tune tech features a stiff base and hex core, with flexible edges that stiffen at the tip.
Complaints aside, the BI/JP Quad fins from Kinetik are actually really excellent fins. Like I said, they feel a lot like a cross between a thruster and a quad, which is very useful as they perform well in all conditions. (I found they went best in fairly hollow small to medium sized waves.)
Check them out at kinetikracing.com.