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K-tech Razor R review

Nucking Foob

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Purchased from Biohazard Cycles for $770 USD, I highly recommend them for their quick customer service and fast shipping. The 80kg-95kg shock with a spring rate of 120 N/mm (sku: 279S-013-270-007) was ideal for my weight.

After installation, the suspension felt improved, providing a plush and planted ride. With the OEM shock (2018+ with rebound dial), it always felt harsh over minor bumps, but this K-tech shock noticeably takes the edge off. And, on the Razor R shock, you can independently adjust the rebound and compression damping to your liking. It outperforms the OEM unit in every aspect. The downside: it's expensive af. 

Also, Ktech customer service is on point. I emailed Ktech USA about getting replacement parts and I got a prompt and informative response which included relevant part numbers. 

Edited by Nucking Foob
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Nucking Foob
Posted (edited)

The stock shock has the wrong spring rate for me. At the factory recommended 4th preload notch, my static sag figure was spot-on at approx. 35mm (I am 81kg with gear). However, there is zero free sag. According to Racetech's suspension bible chart on page 21, there should be 2-8mm of free sag on the rear for street riding. Too much preload is the cause for zero free sag. One effect of no free sag is that the rear suspension cannot dip down on the backside of a bump, nor can it dip down into a road depression. In either case, there is a harsh landing after the bump or depression, or a traction loss when hitting bumps in corners. 

To remedy the zero free sag issue, I took out preload by setting the collar to notch #2. This resulted in about 3mm free sag. However, now the static sag is too great, meaning when I sit on the bike, the rear collapses more since I removed much preload. I would get more than 40mm of static sag.

The stock rear shock sits much lower in its stroke when set to preload #2. One effect of this is bottoming out on large bumps since there is less shock travel available. A second effect is reduced anti-squat: the rear of the bike will collapse more under acceleration. A third effect is a chassis geometry change: the bike is harder to turn in.

With the stock spring, and my weight, it was not possible to get the correct setup, and either way the ride was harsher than it should be. All of the above points are hinting to an incorrect spring rate.

According to Racetech's product page for the 2018 MT-07 (same shock on all 2018+ MT07s), the stock rear spring rate is 10.8 kg/mm (~106 N/mm). However, the recommended spring rate for a 80-95kg rider is 120 N/mm (12.24 kg/mm), according to K-tech's product listing for the MT-07 Razor-R shock. 

After purchasing and installing the K-Tech Razor R, my spring rate woes have faded away. I was getting a spot-on 35mm static sag, with about 5mm of that being free sag. The ride was more comfortable; the same bumps no longer caused the seat to jolt my spine and head. I would also attribute this plushness to the Razor R's damping characteristics.

As far as the adjustability of the shock, I tightened the preload collar half a turn. When you want to adjust the preload, you will be better off removing the shock to do that. Otherwise, you will bust your knuckles and leave ugly scratches all over the preload collars. I have left the length the same as OEM; 310 mm eye to eye. Compression I left at the K-tech recommended of 14 clicks out. 

Rebound I slowed down a little. Recommended is 16 clicks out, but the rebound gets way too fast after the shock oil heats up. I set rebound to 12 clicks out, and this slowed the shock extension down to a level where the rear barely overshoots and settles back down when pumping the bike at a standstill.

Some other good qualities of this shock is that it weighs less than the stock unit. And as fas as cosmetics, red makes you go faster.

Something of note is that the foam washer that protects the rubber bushing in the upper shock eyelet looks like it is "leaking out" and worn on the edges after a few months of use. However the eyelet dowel is still solidly held in place by a rubber bushing. Ktech confirmed this is no issue


Edited by Nucking Foob
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I own the same shock..... I'm very happy with it. I messed around with the settings, and dialed it to what felt "right" to me. I mentioned to my buddy, that I think I got it "dialed in"!!! Then, I went back to what K-Tech recommends- and went back out on track in the next session (to see if it was just in my head?). My buddy was following me, and said "That's dialed in???- WTF? I laughed, and said F-no!!! I went back to what felt "right" to me 😎. I have different settings for street & track. I guess what I'm trying to say, is don't get too hung up on the numbers.... Set it up for what feels right to YOU-

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""W.O.T. until you see god, then brake"

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