SUSPENSION TECH INTERNATIONAL ST 29 A-KIT SHOCK
A home-grown, high-end damper from loamy Rotorua
Words and images: Jeff Carter
Suspension Tech International, despite its name, is a small New Zealand suspension service and tuning workshop based in Rotorua just minutes from the Whakarewarewa Forest. Over the past three years, father and son duo Norm and Dan Cobb have applied their more than 50 years of combined experience to a rigorous design, testing and production process to bring their own custom-tuned coil shock absorber to the New Zealand market. It can’t be underestimated how much of a huge achievement this is for a small Kiwi company.
What’s in the name: ST 29 A-Kit?
Suspension Tech used an extra large 29 mm body and reservoir in their damper, which holds a huge amount of racing shock oil to give longer service life and fade-free performance. A-Kit performance was previously reserved for riders using factory-only “A-Kit” components from motocross suspension giants KYB and Showa, but Suspension Tech sought to bring that level of performance to a mountain bike shock for all riders. The prototype shocks have seen three years of extensive testing on a variety of bikes, with riders ranging from weekend warriors to Enduro World Cup racers.
The similarities between motocross A-Kit suspension and the ST 29 A are the CNC-machined billet components and high-end surface treatments, plus the use of PVD coatings for the shock shaft. The Suspension Tech kit comes with a choice of a Cobalt Blue (TiN/TiO2) or Black “Diamond-Like Carbon” (Me-DLC) coated damper shaft.
Norm explains: “Physical Vapour Deposition coating is a process in which a solid material is vaporised in a vacuum and deposited onto the surface of a part. The materials form a thin metal surface layer, applied over high tensile Hard Chromed Steel to give exceptional wear resistance, ultra-low friction, and that factory look.”
The ST 29 A uses the Sprindex adjustable coil system, available in three lengths and five spring rates per length, providing 40 to 110lbs of adjustment range, depending on rate. The practicality of the Sprindex system is you can quickly and easily adjust the spring rate simply by turning the dial on the spring. The Sprindex springs are linear for the first 80 per cent of travel and then ramping up in the last 20 per cent. This provides great sensitivity and traction through the small and medium movement and progressive support for bigger hits.
Even the bump rubber is custom manufactured. A specially shaped design gives a progressive ramp up to reduce harsh bottoming, and the polyurethane elastomer releases its energy slowly, helping you maintain control and that predictable ride.
Is this the first New Zealand designed and built rear shock for mountain bikes?
I think it is. All the CNC machining has been done by Taupo-based engineer Kevin Jury and the marine-grade anodising is handled by Advanced Anodising in Tokoroa. The steel shock shafts are sent to the USA for that distinctive PVD coating. The graphics are printed by Sign Craft Rotorua. The high-carbon, spring-steel shims are sourced from Australia, and the springs are made by USA-based Sprindex. The custom-manufactured piston rings come all the way from Germany. While other components have been sourced from overseas due to a lack of local supply, Suspension Tech is committed to “supporting local” where possible.
A significant part of the design criteria was to produce a shock with a higher level of reliability along with uncompromised performance and custom tunability. Norm explains his “10+” concept, saying, “We want you to run this shock for 10 years or more.” The shock length, stroke, and mounting can be changed easily and at reasonable cost, making it simple to transfer from bike to bike. This means the shock’s cost can be amortised over many bikes.
Suspension Tech custom-build every ST 29 A shock to order, taking into account rider weight, bike weight, the bike’s leverage ratio and suspension kinematics, as well as the rider’s style and preferences.
Build and internal tuning options
- 2 main piston options
- 2 high-speed compression adjuster spring options
- 9 compression tunes
- 12 total rebound tunes to suit the full range of Sprindex springs
- Internally tuneable climb valve shim stack
- Sprindex adjustable coil springs covering 340 lb to 760 lb rates
Rider adjustments and tuning options
- Sprindex springs offer from 40 lbs to 110 lbs of adjustment (depending on spring rate)
- 15 positions of tool-free low speed compression adjustment
- 15 positions of tool-free high speed compression adjustment
- 15 positions of tool-free rebound adjustment
- 2-position climb valve (actuation to suit different mounting configurations)
Construction
- NZ CNC-machined 6061 T6 construction
- Marine-grade, hard-anodised silver finish
- Strong 12.7mm steel damper shaft—e-Bike rated
- PVD coated shafts in cobalt blue or black DLC
- Metric shock shims
- Large 29mm body and reservoir oil capacity
- All popular metric trail and enduro sizes supported: eyelet 230mm x 57.5-65mm; eyelet 210mm x 47.5-55mm; trunnion 205mm x 57.5-65 mm, and trunnion 185mm x 47.5-55mm.
Norm and Dan have managed to keep the ST 29 A “retailing direct from Suspension Tech” for a very competitive NZ$1799 including climb valve, Sprindex spring and GST (or $1699 without the climb valve).
Ride impressions
I purchased two Suspension Tech pre-production shocks for my Transition Spire analog bike and Specialized Turbo Levo e-bike. I’ve been riding both for the past 12 months without any maintenance issues. The Levo is known for being tough on coil shocks, but the steel shaft on the Suspension Tech shock has been a rock solid performer.
For this review Suspension Tech lent me one of the new ST 29 A production shocks and fitted it to the Transition Repeater. I’ve been riding it for a couple of weeks, including racing round one of the 2W Enduro, landing a spot on the podium.
These shocks are by far the most supple, high-performance shocks I’ve ever ridden. Reliability has been exceptional and ride quality is next level.
One thing that Dan said has really stuck with me: “To perform at the top level you need suspension that is consistent in how it feels, you need to know how it will react when you’re under pressure.”
That’s exactly what this ST 29 A shock absorber feels like—consistent high performance. There’s a meaningful range of adjustment, but honestly I haven’t needed to use it because Dan does such an accurate job of set-up.
It’s looking like I’m going to have to make this a permanent fixture on the Repeater.
Who is this shock best suited to?
Anyone who is unhappy with the performance of their stock suspension and is looking for a performance upgrade would benefit from riding this shock. If you’re comparing this shock with other coil options, the performance and reliability make this a winner, plus there’s the bonus of supporting a Kiwi manufacturer.
Sold on this cool local tech? Best you send Suspension Tech an email: sales@suspensiontech.com or call and talk with Dan or Norm 021 928 778
Details
Manufactured in New Zealand
Price: $1799 with Climb Valve / $1699 without
Weight: 525g (230 x 65 mm) without spring
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Facebook: SuspensionTechInternational
Website: suspensiontech.com