Matris cartridge kit (F12Y124S) review

[pattonme]

The units I ordered a month ago are *finally* in. Matris makes very nicely machined kit (on par with Ohlins and WAAAAY better than Andreani) but alas the F12Y is a 2 3-piston 20mm setup in the same vein as my fixed Andreani, the Ohlins NIX-22 (no FZ/FJ09 application), and possibly the rumored Nitron offering. All rebound is in one leg and the compression is split between a very light base shim stack and most of it on the other leg in the quest for "top side" adjustment.
 
Oddly enough the F15K is cheaper (R3, FZ07, etc.) and uses a 4-piston configuration which is a much more capable setup.
 
Matris' Achilles heel though is the incredibly silly choice in compression-side piston and stack. Both the F15K and F12Y suffer from this malady. By contrast the Ohlins 2-piston (NIX-30) as the name implies uses a 30mm piston which is at least an informed choice.
 
The damping curve of the Matris C-leg is so steep it's beyond words. Putting in a piston with 3x the valve area helps tremendously even with the original shim stack. They supply a liter of 18cSt@40 oil which is on the slightly thicker side and only exacerbates the damping issues. I'm not saying you have to fix the C leg and it's rideable as-is, but I strongly recommend it as bump absorption is really compromised. At the very least run a really thin oil (10cSt@40) to help alleviate the problem. If all you ride are really smooth roads and tracks, you probably won't notice. That said, so far every F15K that went out in OE guise has come back to me with a "please fix this" note attached.
 
The other oddity is that stroke was reduced to 100mm instead of stock 125-130mm. There is no reason for it (LOTS of room in the cartridge) aside from they simply put the mechanical limiter groove in the wrong place. If the top-out spring is fully compressed by the main spring, you'll pick up 25mm more stroke. The OE forks have 125mm before the top out gets involved. What this means is when your wheel floats over a pot hole, the Matris will extend more slowly than the OE which means it doesn't track the road surface as well. 
 
Unlike the Andreani which can be upgrade to use a 3rd piston, the Matris doesn't lend itself to this fix, either. One nice thing about the Matris is it has a spring guide.
 
 
 
I hope folks will chime in on their Matris fork kit experiences.

[td90s]

Well that's disappointing. Was hoping this would be a four piston set-up and with the limited stroke seams like a bad choice to me. At this point looks like your work to the fork or AK20 is the best option. Am I missing anything?

[pattonme]

Correction, there is a base valve in the 'R' leg.
 
The C-leg orifices are much too small even if the system used a 10mm shaft - it uses 12mm which displaces more oil. Here's a contrast between OE comp valving and piston vs after I fix it. A 1" bump at 60mph is 200 in/sec of shaft speed. Which do you think has a prayer of absorbing the impact? In both cases I'm pushing as hard as I can.
 
OE
[video src=https://dl.dropboxusercontent.com/u/180639/Matris/OE.mp4]
 
Fixed
[video src=https://dl.dropboxusercontent.com/u/180639/Matris/Fixed.mp4]
 

[pattonme]

I edited the first post to further explain the observed travel and top-out spring concerns. But here's a biggie.
Notice the cartridge doesn't sit straight. This can cause rubbing between the spring seat, spring and the fork's inner wall. Apparently their machining center is doing a lousy job of staying on axis when it re-grips. Since my lathe is decidedly non-precision I wouldn't dream of making the threaded base except in one shot to prevent problems like this.
 
Andreani and Ohlins manage to keep their threaded bases on-axis, so what's Matris' excuse?
 


 

[foxedupone]

Ask Matris if they need a new designer and factory foreman.