'Matter'

MATTER: Stafast Suspension Stem

 

Tested: Stafast Suspension Stem, 105mm (1-1/8″ clamp, also comes in 95mm)

Price: $350 USD

Tester: Matt Surch, 6’1″, 165lbs

“You know what I think makes the most sense? Carbon rigid fork, suspension stem. That way you can maintain pretty low weight, AND preserve the aerodynamics of the front end.”

“Yeah….maybe…..”

Iain Radford and I are on the way back from the second edition of Vermont Overland at Suicide 6 outside Woodstock VT. We’ve just finished a day of highs and lows, both literal and figurative. We’ve climbed hundreds upon hundreds of meters of dirt road and trail. We’ve ridden with our team-mates, we’ve ridden with Ned Overend. We’ve dropped and been dropped by both. Our team-mate, Maja, has gone to hospital with a broken collarbone and a concussion, and we’ve spent the afterglow of the race helping Steve and Gia, her travel-mates, get her insurance in order so she can make it back to Canada without bringing a crippling debt with her. As the hours pass, Richard Grieve and Mike Reeves up front in the van, Iain and I process the day’s experience, and relate what we felt and saw to our pre-race perspectives on bike set-up.

By way of context, we’d been talking for some months about the ‘ideal’ bike format for courses like Overland – which is unique in the East at the moment – that blend fast dirt roads with challenging ATV-style trails, also known as ‘Vermont Pavé’. After the inaugural Overland GP in 2014, which was totally badass, we returned home wondering whether we’d be better off the following year on our VTT bikes. It seemed unlikely, as both are fairly heavy, being of rugged steel construction suited to mountain biking. Yes, our gearing was ok, and we had great tires on the bikes, but were they race-appropriate? Probably not. Why did we even want something different than our cyclocross bikes with 38ish mm tires?

Flat tires, dented rims. Both Iain and I know our strengths and weaknesses. On the flats, we’re both good, and we’re pretty good on the climbs. The descents are where we tend to have an edge, or at least we often have to descent at the height of our abilities to regain contact with others after being dropped on climbs! Traction isn’t usually a problem on the terrain we normally race CX bikes down, nor is passing through rough stuff. The shit hits the fan when we smash into stuff and flat. The way we normally try to deal with that potentiality is by using tires that will allow us to avoid flatting on the roughest descent of a race course. However, sometimes there’s one section that is bad, but the rest is much more mellow, rendering larger tires wasteful (in terms of energy). So, what about using tires that provided just the right amount of traction (usually file treads), and using a little bit of suspension to handle the big impacts? In other words, why not follow the evolutionary path mountain bikes took in the 1990s, perhaps skipping a few dead ends?

I came out of 2014 thinking a 650B frame in a light material – steel, aluminum, titanium or carbon – with a Cannondale Headshok fork with lockout would probably be the best option, especially if the fork blades were shaped for aerodynamics. After all, the evidence suggests that the front end of the bike counts more in terms of the system’s aerodynamics than everything behind it, and I remember well how much I loved the Headshok on my 1998 Cannondale F2000. Yet, Iain and I had just raced against Tim Johnson on pretty much that concept bike itself, the recently released Slate. Aluminum, 650b wheels with tires similar to Compass’s Extra Leger Hetres, and a Lefty suspension fork. But that set-up didn’t seem to work as well as we’d imagined it would, as the race was decided on the climbs, not the descents. Johnson dropped off the pace at the front on the first big climb, and it seemed like the benefit the suspension fork provided elsewhere didn’t outweigh the weight penalty it imparted. His tire volume, about 42mm, seemed good, but with only a herringbone tread, they couldn’t really shred the tough stuff as well as the frame and fork might allow. So Iain and I were questioning the utility of suspension for this sort of racing, at least options that are currently available.

Informing this thought process was the bikes of Rob English, which are the closest thing to present-day constructeur race bikes I can think of, and Tom Anhalt’s (steel, btw), which incorporates his ideas gleaned from independent research on aerodynamics and bike performance.

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Photo: Rob English

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Photo: Tom Anhalt

English’s and Anhalt’s bikes’ focus on front-end aerodynamics led me to a somewhat surprising idea: use a suspension stem. Naturally, suggestion of a suspension stem took both of us back to the 1990s, when notable pro mountain bike racers used suspension stems to great effect. I never understood how, but I distinctly remember Henrik Djernis racing exceptionally well on his Sortride-equipped steel Ritchey. He won the World Championships XC race on the bike below (he won the WC title three times).ritchey

I always wondered how Djernis and others on the suspension stems from Girvin and Softride could handle their hands moving up and down in relation to their hips. Djernis was an accomplished cyclocross racer, so it made sense that he wanted a similar feel on his mountain bike, but a little less brutalizing. What perplexed me more was the use of the Softride beam bikes, which seemed completely…wrong.

Suspension stems, beams, Unified Rear Triangles….each were and are suspension approaches that have always been described as ‘suspending the rider’ rather than ‘suspending the bike’. This distinction made sense to me as a teenager reading all the English mountain bike magazines I could get my hand on. But 20+ years later, I consider this a false dichotomy. Why?

This is sort of similar to talking about the aerodynamics of bikes without riders on them. Many bike companies measure their bikes’ aerodynamics this way – without a rider on them – and then tell us all how much better they are than everyone else’s. This approach is bogus, because the aerodynamics of a bike change when a rider is on it, riding it. Tom Anhalt has done some good work on this.

Suspension is similar, because the bikes don’t ride themselves. When riding, the rider and bike form a system, and that system is suspended, one way or another. In the case of a rigid road bike, the system’s suspension elements are:

tires, wheels, fork, frame, handlebar, stem, saddle, seatpost, cranks, pedals, hands, arms, legs

In a future post, I’ll get into tires, specifically their suspension attributes in relation to rolling resistance, traction, and aerodynamics. Since you are obviously interested in learning more about the performance of the Stafast suspension stem, let’s break things down as staight-forwardly as possible.

  1. Why might one want to use a suspension stem?
  2. What is the Stafast Suspension Stem?
  3. Installation and set-up
  4. Observation and performance
  5. Conclusions and MATTER Rating

Why might one want to use use a suspension stem?

On a typical cyclocross bike most of the suspension duties in the system, from high frequency to medium sized impacts, are carried out by the tires. The larger the tires, the more isolated the rider will be from a great deal of the road’s imperfections, requiring h/er to only deal with large obstacles, for example, bunnyhopping over a pot-hole.

But….even if a bike can fit up to 45mm tires  (which are big enough to handle pretty big impacts, but obviously not at low pressures), they take a lot of wind drag. I can discern the difference in power required to ride at a given speed on 38mm Compass tires versus 33mm Compass tires (same construction on both) on the same road. 45mm tires are exceptional on rough surfaces, but are not the most efficient option for decent or good roads. Smaller tires would work better most of the time, but what about the abuse?

Every bike has a maximum tire size it’ll fit. Most cyclocross bikes fit something like a 40mm-wide tire; some will take a slightly larger tire, others smaller. So the upper limit of tire volume is fixed. The suppleness of tires is also limited; there is a ‘most supple’ option on the market, and it’s a tubular that one probably would not want to take off a cyclocross track or supported race route. One can fit the largest, most supple tire that fits, on wheels that are somewhat ‘comfortable,’ and the rest of the suspension in the system is left to the frame, fork, and components listed above’s ‘flex’, in combination with the rider’s ability to absorb energy directed up into the feet, hands, and butt.

Suspension forks, as discussed above, are heavier than rigid forks, and less aerodynamic. I can’t imagine how they could be close in weight or aerodynamics. Suspension stems, on the other hand, while heavier than regular stems, don’t seem to be as un-aero as a suspension fork would be. Fitting a suspension fork requires lengthening a fork’s axle-to-crown distance, which thus raises the headtube. That means the handlebars come up, unless an aggressive stem drop is used. I personally already use a -17 degree stem on my cyclocross bike, so raising the headtube without also raising my saddle would necessitate an even lower stem. These are few and far between. But more to the point, the fulcrum changes when you raise the height in relation to the front axle at which the stem attaches to the fork steerer. Yes, you can achieve the same hand position by changing stem drop, but this doesn’t mean the front end behaves the same way.

In contrast to a suspension fork, a suspension stem allows you to maintain the same axle-to-crown value as usual, and possibly even the same hand position as normal. In this case, your hands will drop in relation to your saddle when you compress the stem. This is something that does not happen with a suspension fork; those two points of contact remain constant. Thus, each system is more and less suited to certain kinds of riding.

Suspension forks will always perform better than suspension stems can on steep terrain, because they help maintain traction better, and don’t change your hand position in relation to your hips. The angle at which you hit obstacles will also affect the amount a fork or stem can absorb energy. A stem won’t be able to absorb much when the body weight is far back, somewhat pulling on the handlebars. In order to move, they effectively have to be pushed down and forward.

What is the Stafast Suspension Stem? (398g)

Made for 1-1/8″ steerer tube bikes, the Stafast stem is forged from aluminum, and is composed of four parts: steerer tube clamp and suspension arm, stem body, removable faceplate, and air-oil shock. The stem’s parts are all held together with heat-treated cro-moly bolts, which I was please to see were installed with copper paste, which is the best option for preventing bolts from seizing. I’ve never seen it used on a factory part before, but I often use it when I assemble parts.

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The upper portion of the stem is fixed to the steerer clamp at one point, making the stem a ‘single pivot’ design, in contrast to Softride’s parallelogram design. The shock site in front of the steerer clamp, running almost vertical between it and the upper stem. It is mounted with what appear to be Delrin bushings so that it it free to pivot at each mounting point, typical for every suspension design I’ve ever encountered.

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In the box: instruction, stem, top cap and heat-treated cro-moly bolt, shock pump, wrench for shock rotation (adjusts stem’s angle).

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Installation and set-up

Assuming you have a long enough steerer tube (size) to fit the stem, installation should be pretty easy. If you are setting up the bar into a higher position than before, you might have to change to longer cables and housing.

Specific Fitting Considerations

  • A special top cap is used to compress the headset assembly, given the placement of the stem’s pivot. So you wo’t be able to use a fancy stem cap, or mount a phone or camera in this location.
  • The steerer clamp is considerably taller than most (43mm depth), so it is necessary to ensure one has enough room to work with before committing.
  • The tall steerer clamp will raise the haldlebars if one is running a slammed stem position. One can adjust the stem downwards to compensate for this, but not entirely.
  • 95 and 105mm lengths will work for many, but not for all. If one requires a shorter reach with a road handlebar, one might be able to swap to a shorter reach handlebar, and vice verse. If the stem was much shorter than 95mm or much longer than 105mm, I suspect the shock would be under or overwhelmed by the leverage on it.
  • Bikes that use a steerer-tube-mounted front brake cable hanger will not accommodate the stem without setting up the hanger off-centre. The lower shock mount sits low, pretty much exactly where most hangers sit. If ‘slammed’ all the way down (no spacers underneath it, just the cable hanger), there will be little or no room for a cable hanger. One might be able to set it off to the side and still maintain good cantilever brake set-up. Linear-pull and disc brakes would not be affected at all by the stem design.

I installed the stem on two bikes for testing:

Steelwool Truffle Pig cyclocross bike – My usual stem is 120mm by -17 degrees, so swapping to a 105 length with less drop was a big change in bar position. I used the provided wrench to rotate the shock in the direction that dropped the upper stem down as far as possible. This put me into a useable riding position. I use linear pull brakes on this bike, so all I had to do was install a longer piece of housing to accommodate the higher position. I aired the shock up to nearly 200lbs, more than my body weight. The provided shock pump was of typical middle-of-the road quality, on par with other pumps typically provided with suspension products. It uses a special long chuck to fit into the shock; other pumps wont fit. I had to fiddle with it to get it to thread on just the right amount; avoid tightening it more than you need to.

Niner MCR 29er with drop handlebars – I normally run a 110mm stem on this bike, so the 105mm Stafast was barely different. Already dropped to its lowest position, the stem gave me the opportunity to try riding the bike with a higher hand position than normal which would allow me to ride more in the drops. Drop bar mountain bikes are usually set up so that the drops are the typical hand position. I dropped the air pressure slightly to see if I could get more pre-load into the stem, and reduce rebound speed.

Observations and Performance

I was very curious to find out how the Stafast stem performed under high intensity riding conditions, so I installed it onto my cyclocross bike for the first race of the Eastern Ontario Cyclocross Series race I attended at the Renfrew Fairgrounds at the start of October.  Being a madison format (pairs tagging off each lap), this was a perfect no-risk opportunity to test the stem. Given the course covers ground that is for the most part quite rough, the scene was set for a good evaluation.

I was pleasantly surprised to find that I didn’t notice the stem’s movement most of the time. Yes, twisting under sprint and hard accellerations out of the saddle was discernible, but not bothersome. It was the large holes I hit that compressed the stem a lot and therefore set off a forceful rebound and top-out that was distracting. At the same time, there was a very firm rutted corner on the course that I found I could hit with higher speed than I’d be able to do with a rigid stem, so I tried to use that turn to gain time on my rivals. Without any barriers to bunny-hop or big moves of any kind, I found the stem quite efficient over the course, and my best lap time was the second best on the day, behind Derrick St. John. Over the rough ground I found it easier than usual to keep the power down, and I thought of the stem as an advantage over my competition, which gave me a little extra confidence. It was interesting to see that a number of the young riders at the race were really excited to check out the stem on my bike, while older riders were intrigued, especially those who remembered suspension stems from the 1990s!

On my Niner I had the opportunity to do a number of rides on the stem covering a good range of trails and paved surfaces. Given the higher bar position, I was able to ride descents in the drops more comfortably than usual (this was the plan), which proved favourable in terms of stem performance. While on the hoods, the leverage on the stem was at a maximum, providing the maximum amount of travel (I reached more than 2″ travel at the hoods, and never bottomed out), which translated into the maximum rebound speed. In contrast, while in the drops, since some of my weight was actually pushing forward, the action of the stem was muted, and topping out was far less common. I found riding in this position rendered the stem’s movement imperceptible most of the time.

Where the stem showed a clear pitfall was during occasions where I had to preload the bike to clear an obstacle, such as a fallen log. The feeling us unlike that of a suspension fork. When pushing down, the stem compresses, then when pulling up, it rebounds, and comes to a stop, at which point you are actually pulling up on the front end of the bike. I found it very difficult to execute this move well, despite having many years experience executing bunnyhops well.

On the flip side, during a night mountain bike ride with a couple fast team-mates, Mike Reeves and Iain Radford, I struck a waterbar I never saw hard while in the drops and got absolutely launched, yet maintained control. Pulling out of the trail onto a connector road, I was 100% certain the stem had saved me from a head-over-heels crash. Yes, I’ve actually done one of those before. At least. I was really happy with the stem’s ability to absorb the impact I took and buy me a fraction of a second to adjust my body to avoid crashing.

With all the topping-out the stem did under my use, I was not surprised to see it developed some play in the shock’s mounting bushings. This is a common issue on rear shocks on mountain bikes. I even had a suspension fork, a Manitou 4, come apart as a result of it’s excessive rebound and top-out. The top-out issue is essentially the one issue with the stem, in my view, and it might not be terribly difficult for Stafast to address. They indicated to me when I mentioned it that the shock tends to slow down it’s rebound after some use, but really, that’d need to happen before the bushings wear out. An option could be to install a top-out bumper inside the shock on the piston head, which would soften the return stroke. However, the shock is very small, so I imagine this would be tough to fit in. Alternatively, either compression damping OR rebound damping would help, if not both. Compression damping alone can help with reducing rebound speed, since it leads to slower compression rates, and thus slower rebound rates. However, it would not address the input of pulling up on the bars, such as during a bunnyhop.

Ideally, a shock design would follow the lead of those used for cross-country bikes these days: a platform damping system. A platform reacts differently to different speed inputs. A slow compression, as when pedaling or loading for a bunnyhop, is met with a lot of compression resistance. A fast impact, as when striking an obstacle, is met with open compression damping. This functions to damp rider inputs and create a more responsive, ‘stiff’ feeling platform while also affording useful suspension performance.

There’s nothing inherent in the suspension stem design that makes a platform-style shock an impossible component. In my view, such an approach, especially if combined with a parallelogram pivot design, could make for a very high performing suspension option. The additional weight taken on by the system seems like it will always be lower than a suspension fork, and a stem affords greater opportunity to maintain an aerodynamic fork, hub, and head-tube design. Inherent limitations would likely be stem length and angle, both of which could make an already niche component difficult to justify building at a fairly high retail price, as we’d expect if the shock technology ratcheted up.

Conclusions – MATTER Rating 7.5/10

The resounding question here is simple: who is this stem for? It depends. It always does.

The stem’s construction, from a structural integrity perspective, was confidence inspiring. Anyone who knows how I ride bikes – not gently – will know this is a strong vote of confidence. While I don’t think the current version of the stem is the right fit for those who ride off-road aggressively, either cyclocross or mountain bike format, due to the top-out issue, there are many other riders who might find it an enhancement to their riding experience.

As a component that a rider can purchase and have fitted rather easily, there is a lot of potential here for those looking to simply smooth out their ride. The fact is, most bike riders don’t know what a bunnyhop is, let alone how to do one. As it is the stem will meed the needs of many riders who find their suspension forks are too heavy and overkill, those who have rigid bikes that are beating them up, or those who simply want to branch out and try riding rougher surfaces.

From commuters to cycl0tourists, recreational road and mountain bike riders and cottage dirt road cruisers, there are many riders out there for whom the Stafast stem would improve comfort, stability, and overall ride quality. I didn’t have opportunity to try it on my fat bike due to local conditions, but the Stafast stem could actually be very useful for those who ride trails that get post-holed by walkers, or are just generally rough. Fat bikes don’t see much bunnyhopping, and suspension forks are overkill for a lot of riders, but the Stafast stem could be just right for many.

I rate the stem 7.5/10 for two reasons: 1) The cost, while understandable given the scale of production, will likely come across as high for the type of consumer the stem is most appropriate for: recreational riders. 2) The shock could use some work, as detailed above. I count the bushing wear as closely associated to this, rather than a separate issue.

I would like to thank Stafast for loaning me this stem for testing; much appreciated. I found the process very illuminating, and rather than coming out of it with all my questions answered, I’ve got more! I see potential in the suspension stem format for a lot of riders, ranging from recreational all the way up to the aggressive elite level. The stem format makes is easy to tailor a bike for events that stray from the norm that requires a rigid fork, lending versatility to a given platform for across a wide variety of applications. If the tuning were to improve and the weight were to drop, I could see this stem being a viable kit option for dirt road, cyclocross, and fat bike racers looking to be prepared for whatever events and adventure rides threw at them. Where others might see old technology and bulk I see possibility. I look forward to seeing what the future brings!

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