When you understand the thought, understanding, and development that goes into something like the Type II fork, you can see how subversive he is as a bike building and design talent. Rather than aggressively adopting and reinterpreting the components available with flashy paint jobs and kits as many other builders at NAHBS do, Steve bucks big industry through developing and fine tuning the “rigid” frame and fork and their relationship to the individual customer in a way that cannot be replicated in production. See, Steve’s not as susceptible to new technology as other builders. He knows he doesn’t have to play by big industry trends… and he never has, as one of the extremely rare bicycle builders or designers in the world who have designed bikes holistically- frames, forks, components, and all.

That said, I was ecstatic to see what was coming across the social media on the Steve Potts channel prior to NAHBS. Out of all of the previews I’d seen for framebuilders coming to the show, his booth became my main draw. Out of three pivotless suspension frames he has developed with John Castellano, two would be making their way to NAHBS. “There are no parts to wear out, they are incredibly strong, and they are super comfortable to ride.”

First up is the Silk Ti XC bike with 1.75in rear travel. Steve has been building Castellano suspension bikes for fifteen years at a rate of about ten to twenty bikes a year. Without a pivot, the suspension is inactive when you’re out of the saddle so it climbs like crazy. “With the unified travel rear triangle, you don’t activate the suspension unless you’re on the saddle… so this is a super duper suspension bike. Basically, it kicks butt.”
 

The chainstays of each of the pivotless frames were optimized using finite element analysis for their unique purpose- flexing of course. So the 1.75in travel bike has these chainstays, designed to handle a smaller displacement.

Steve demonstrates the deflection shape of the chainstay in compression.

As impressive as the frame is this suspension rack design. “I made this rack two nights ago; it was an all-nighter.” As the multi-phase elastomer shock compresses, the rack structure is also allowed to compress.

Steve found himself having to move the shock inside of the front triangle due to space contraints between the seat cluster and the tire to accommodate 3.3in of travel for the Silk Ti LT.

The resulting frame configuration is boss.


Again, Steve points out the areas where the stays are designed to flex to accommodate the extra travel. “This chainstay development is 15, 20 years old… we’ve had a lot of these out and we’ve never had one break. They are incredibly strong.”

Beyond titanium, the booth also featured several more affordable steel bike options. Why build these affordable, steel versions? “I love building bikes and I want to get more people on [them].”

This white steel trail bike was designed around 27.5+ tires (specifically 3in tires on a 45mm rim), a Boost drivetrain, and Pass and Stow Racks. It’s also paired up with a new Type II plus fork, designed with straight 1-1/8in and tapered 1-1/8 to 1-1/2in steerers.

There was also this gravel adventure bike, also available. With clearance for up to 50mm tires, your options for surfaces are wide open with this ride.

To accomplish this build, Steve made a Mini Type II fork around it. Many builders or manufacturers just use really stiff and heavy steel blades to strengthen them for disc brakes. That’s not Steve’s style. To help keep the fork supple while allowing it to resist braking forces, Steve designed and implemented this ultra long disc brake mount which is hooked into the crown.

But that’s not all that was in Steve’s booth. Check in later this week for a really neat interview with Steve on my personal favorite bike of the show (aside from the Prince Tribute Peacock Groove, of course) his 1986 Steve Potts gravel grinder- a very, very interesting bike.

StevePottsBicycles.com

30 COMMENTS

  1. How is that silk ti a URT? (it’s not). And why is he championing it? It’s been universally panned by most mtb’rs who lived through that era.

  2. “you don’t activate the suspension unless you’re on the saddle”- So, riding down any sort of technical terrain your ful sus turns into a hardtail. And that’s a good thing?

      • It seems like the designer is somehow differentiating weight from a rider sitting vs standing. Which is weird — in both cases the weight is delivered rigidly through the rigid front triangle. Does the sitting provide a larger torque about the bottom bracket?

  3. This bike is not a URT. And, for the record, you do NOT want the suspension on a mountain bike to only be active when you’re in the saddle. URTs did generally prevent suspension bob when out of the saddle – but they also prevented the suspension from doing much when *descending* out of the saddle (ie, basically the entire time). They died out for good reason.

    So, um, if it was URT, that would be bad. But it’s not. So that’s good.

    Maybe have someone with some knowledge of suspension design edit this sort of thing before publication next time.

    • Howdy Justin!

      I pulled “Unified Travel Rear Triangle” as a direct quote from Steve at the show (repeated and checked by Steve). That is why it is used as it is here.

      • A URT has the BB attached to the swingarm, with a pivot between the BB and the front triangle/saddle.

        Like this (the universally despised Trek Y-bikes):
        http://mombat.org/TrekY22.JPG

        Note the pivot located above and forward of the BB.

        Apparently Steve has his own set of terminology, that’s fine. It is very confusing to readers, however, to hear the term URT used here.

        • Justin- I’m picking up what you’re putting down. I’ve reached out to Steve for further comment based off of your feedback.

        • Justin is correct. He accurately defines a URT suspension design.

          I don’t care what Steve Potts thinks, he is misusing the term. His design is a pivotless suspension like the Moots YBB and many other variations that have existed for decades.

          The Potts design is somewhat unique since he uses a flat plate for the full chainstay where others only use it for a portion of the stays near the BB to allow for enough flex in the rear triangle.

          The more common term for this basic design is a “Soft Tail Suspension”. It is similar to a Hard Tail frame but includes a flexible chain stay design near the BB along with a spring or shock connected to the seat stays.

            • So he’s not human? It’s impossible for him to make a mistake?

              Not to mention the corroborating info from other posters, but you believe what you want to believe.

        • First of all, Anna certainly knows the difference between a URT and a soft tail; she is trained as a mechanical engineer and has worked in the industry for years. She was merely reporting what Steve Potts said, and conscientiously at that.

          I get the impression that some of the peanut gallery don’t quite grasp who Steve Potts is. Concluding that he can’t tell the difference between suspension designs is a little like supposing that Keith Richards can’t remember which manufacturer makes Stratocasters.

          Steve Potts is not some mediocre framebuilder trying to make it in the industry. He’s one of the founding fathers of mountain biking. Joe Breeze, Gary Fisher, Tom Ritchey: Steve Potts was there. Steve Potts co-founded (with Mark Slate and Charlie Cunningham) a little company you might have heard of: Wilderness Trail Bikes (WTB).

          Potts was there for clunkers, there for URTs, there for soft tails and he was at NAHBS this year; it’s an impressive run. Either he’s a dim bulb and despite his immense experience (and MIT engineering degree) couldn’t keep suspension designs straight, or he just misspoke. The simplest explanation is often the best one.

          • Sure, Steve is awesome. Anna is awesome. The bike in the photos is awesome (at least if you like softails.) But the pivotless softail bike in question is not a URT or anything close, so somebody either *really* misspoke (and at some length: the description of the suspension, setting aside the “kick ass” part, accurately describes a URT) or else they were talking about an entirely different bike not shown in any of the photos in this article.

            I think most of us would just like some clarification of what on earth (reminiscing about older/unpictured bikes that *are* URTs?) happened to make the article so confusing. I don’t think anyone is questioning Steve’s history or skills (you’d have to be nuts!) or Anna’s generally great reporting – but something went wrong here. It would be good to correct it or at least know what Steve *was* talking about.

      • Maybe he got confused. Castellano definitely made a URT frame for Ibis in the Szazbo and also used for the Schwinn Homegrown, the Ibis Bow Ti, and the WTB Bon Tempe. But the Ibis Ripley, Silk Ti, the Castellano bikes and now these bikes are not URT, but simply softails in the same way that the Moots YBB and the original and current carbon C’dale Scalpel’s are softails. The above bike uses the same exact chain stay at the Ibis Silk Ti. Hey, loved it then and love it now.

        • Exactly, there is no need for any fancy terminology here. It’s just a softail, which is for all practical purposes just a very low pivot single pivot. It has some big advantages in simplicity/weight, and big disadvantages in suspension kinematics (both wheel path and squat, mitigated by the fact that there’s not much travel to begin with).

          Softails like these have been around forever and probably always will be for folks who want just a little bit of travel and no bearings/bushings/pivots to maintain. They are great for that purpose. But they are not URTs and they do not isolate the suspension when out of the saddle like a URT (protip: that’s a *good* thing).

          • omg… everything about this is hilarious. the bike is definitely not a URT. on top of that, all the side load is going to go right into that shock when the plates twist. it’s just bad…everything is bad.

          • Yeah, it seems almost too coincidental that there is confusion about if this Castellano designed bike is a URT (it isn’t) and that Castellano designed one of the most prolific URT designs the “Sweet Spot”. It seems like there must have just been some rushed miscommunication. I mean, if Potts and Castellano both consider this softtail a URT, then what the heck do they call the actual URT Sweet Spot design of the above mentioned bikes?

            • Regardless of the confusion over the terms/bike, I think it’s fair to say that the mountain bike world would not agree with the description of URTs as “kicking ass”…

  4. Wouldn’t a non-pivoting suspension linkage allow for all sorts of torsional flex? In my book that’s not a good thing.

    • Cannondale has been doing it off and on with the Scalpel for years. I think that on the Scalpel the upper shock link can resist the twist that the chainstays allow. On this bike, there is no upper link, but the shocks are of a rudimentary enough nature that the shock can take the load without much durability concern. How much stiction it has when side loaded though, I couldn’t tell you.

  5. Steve’s stuff is always a couple of steps beyond others at this show.
    Although I am not a fan of flex stays, I do love the concept. It is mainly a target for 50+ and women who go slow on fire roads and like pretty bikes. That said elastomer shock? Ill have to go find my old Halson Inversion fork.

  6. Hi all, I have never responded to any story before but thought I would to apologize for the confusion, First, Anna Schwinn is awesome, she doesn’t miss anything on the bike and is really fun to work with because she loves cycling, so I am sorry to have caused Anna any trouble. Both John Castellano and I worked three days straight without sleeping ( yes, not very smart ) and then drove 12 hours to the show so to say the least I was not very well rested or clear thinking. I have build a lot of bikes, every kind , even URT’s and of course a lot of John’s Pivotless bikes, and the point I was making is how much I liked riding the Silk Ti was and how efficient it is on the climbs.I was certainly not very articulate in my descriptions ,so you are all right also, so again , sorry for the confusion. This is not the first mistake I have made and I am sure that it will not be the last, and hopefully I will make more bikes that will fit someones needs and put that big smile on their face, after all , the bike was built to be simple and to bring joy. Thanks again and keep riding and smiling, sincerely, Steve Potts

  7. Steve’s workmanship is excellent, but the deign and engineering are a little lacking. That front disk tab, for instance. The tab still exerts force at the base of the leg, and that long extension is going to stiffen that one side, also putting odd forces back into the small attachment near the top bolt. No bueno.

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