Sufur-cycles

 20 questions – A chat with frame builder Rufus Wenlock from Süfur Cycles

Not many people race one of the worlds hardest bikepacking events on a bike with a frame they built themselves. Even fewer get on the podium. After battling illness part way through the 2024 Silk Road Mountain Race Rufus Wenlock bounced back and rode himself into third place in this gruelling event. His quirky "Süfur" frame design was turning heads with its unconventional design. But Rufus didn't just appear on the scene from nowhere. With his background as a world cup mechanic and bike shop owner he's been around for a while and had often thought about making some of his ideas a reality. What better place to test them than in the field. 

Podium finishes in the GB Divide, the Trans Balkan, and the Tour Te Waipounamu have only helped Rufus to solidify his ideas in a frame design that culminated in a custom build for his good friend Joe Nation. Joe had unfinished business after finishing 3rd in his rookie year in the 2023 Tour Divide and wanted to give it another crack. Rufus designed a bike from the ground up to fit Joe’s specific skill-set, and the particular demands of the 4400 km long event. Unfortunately, Joe's attempt finished with a scratching and suspected pneumonia, but there is a lot to know about the thinking behind Joe’s bike, and the bikes that came before it. Read on to learn more about the Süfur Cycles process and what comes next.

So, Rufus, I understand that the original Süfur design was partly an exercise in maximizing frame bag potential, did this philosophy carry on through to Joes design?

Yes, the idea was that I knew where I wanted my three contact points to be and as long as they were in place then the rest was just a matter of maximising storage capacity for bikepacking which followed on nicely into Joe's design. His bike was very much based on the bike I’ve been developing over the last couple of years.

Were there any downsides to the construction of the Süfur Divide's curved seat tube design, apart from the difficulty of construction? 

At the time of coming up with the first prototype I didn't have a tube roller so it was a matter of finding a local business that could do that for me. This proved tricky as nobody had the forms for the tube diameter I wanted to use, after a lot of hunting I found there was one place in the north island that could do it. I sent some tubing off to them and received a rolled tube that was quite far from the specs I gave them. I managed to use a few techniques to get it to spec. This made me realise a tube roller was something I would need in the future! Paying someone else to do a bad job really frustrates me.

Some people have speculated that the curved seat tube might be stiffer than a traditional design, is this what you have found? 

The initial idea was that the curved section would compress a little like a spring. The first version did end up a little stiff though. Subsequent versions are much better with some geometry and material changes.

It can be hard when you only ride the bikes you’ve built, your point of reference becomes more and more limited. It was very validating when I used this technique on Joe's bike and he mentioned it was super comfortable.

With the design of Joes bike for the 2025 Tour Divide you went big on aero. There are massive gains to be made in optimizing for aero even at very slow speeds, and the longer you are out there, the bigger the gains. You lowered the frontal area of Joes bike by dropping the bottom bracket down and running shorter cranks. Have aerodynamics always been at the back of your mind? 

I would say that aerodynamics is something I always consider but it’s not a driving force. The bike I built for Joe was very specific to him and the Tour Divide, we designed everything around him being in the aero bars as his primary position. Besides that, we were wanting to keep all his gear consolidated inline with the frame and reduce his frontal area as best as possible. There were a lot of ideas that we tried but never made it to the final design.

We weren't about optimum aerodynamics; it was more about how aerodynamic we can get whilst still being able to efficiently bike 20hrs a day for two weeks. Like I mentioned before it wasn't the driving force behind our decisions, a race like this is more about who can hold on for the longest rather than who is the fastest. You see a ton of people with crazy setups who are absolutely flying and then scratch after 5-6 days because they couldn't ‘hold on’.

It was more about striking a balance between aerodynamics, comfort and efficiency.

The "sail effect" is a well-known phenomenon in the time trialling scene where side wind against a wheel or frame can propel your bike forward. Joe's large full-frame bag cleanly surrounded by his frame would have been really useful for utilizing this effect. Was this part of your thinking from the start or just an added benefit?

Yeah, this was definitely the plan, we considered having a half frame bag with bottles at the bottom but decided to go full frame bag and have the lower half a separate compartment for a bladder.

Was the choice of a rigid fork on Joe’s bike to do with weight, height, or the ability to attach water bottles or accessories. Was there anything special about this fork?

There were a few reasons for the rigid fork. Joe wanted to keep it light and with his MTB background we knew he could still handle the bike fine in some of the technical sections with no suspension. Another was that with the bottom bracket and bars getting dropped the headtube was getting very short, the shorter axle to crown measurement of the rigid fork allowed a normal sized headtube and more front triangle space.

What were some of the other things you were trying to achieve with the frame design. You mentioned the dreaded peanut butter mud that can bring a bike to a standstill on the Tour Divide route. 

Peanut butter mud was a big consideration; Joe had an awful time with this on his first run of the TD. On top of making sure there was enough clearance I designed the bike so there was a little less clearance at the seat stays so that all the mud clogged up high away from the drivetrain and nothing caught down on the chainstay area.

How much is weight a consideration, obviously you don’t want something fragile, but did you go with any fruity frame tubing? Did you ever actually weigh Joes frame?

To be honest I have no idea how much it weighs, Joe was happy with the weight though.

I see you send your 3D stuff to RAM-3D. Is there ever any other work done by them after you have sent them the files or is it just printing? 

They do some finishing work to remove all the supports required during printing and then once I receive them, I machine all the high tolerance areas to spec as there can be a small amount of distortion with 3d printing.

3D printing seems like a real game changer to me. Is there a bit of snobbery among old school frame builders who might look down at the process at all?

I’ve not experienced it but I’ve certainly seen some snobbery out there. I just see 3D printing as the next evolution of frame building, there was a time where you weren't called a real frame builder if you didn't hand file all your mitres but now everyone has a milling machine for that and I think 3D printing will be the same.

What is it about the CAD work that takes up so much time when designing a bike from the ground up? 

It’s often hard to know exactly how you want a part to turn out. You might begin with a solid idea in your head or some rough sketches, but once you start designing in CAD, you see how every detail is referenced and affected by the rest of the system. It can take a long time before the design on screen matches what you imagined and even longer before it performs the way you want it to. 

Do you think it's possible to make some kind of a living in NZ as a frame builder?

This is what I’m working on right now. A little while ago I finalized the design I’ve been prototyping for the last couple of years and plan to bring it into production. I’ve spent the last couple of months establishing relationships with suppliers and trying to make everything work. Doing this from a small country with no industry is hard but I’m hopeful it will work.

The bike industry is in a strange space right now, I feel like there is very little connection between what something costs and its level of quality. I’m hoping to strike a middle ground with my pricing, considering all the frames will be made by myself they won’t be cheap but I wouldn’t consider them expensive either.

Is there a particular frame builder whose work you admire?

I like the weird and innovative stuff. To name a few builders like Crowe Rishworth, Drust, Creature and Bender, all get me thinking.

You’ve done some pretty gnarly bikepacking events by now Rufus. And I’m sure they are all hard in their own ways. I keep hearing that the GB divide is one that is often underestimated. Obviously, weather plays a big part in any event, but which one had you on the ropes the most?

Yeah, I’ve done a few now and they all leave their mark! I’d say the Trans Balkan Race well and truly had me on the ropes, I still didn't have a lot of experience at this point and was pushing sleep deprivation to the limit. I have a lot of wild memories from that one...

Thanks for sharing your thoughts, Rufus. I'm sure everyone is looking forward to what is coming up next from Süfur Cycles

Image credits to:
Anton McGeachen 
Joe Nation 

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OPENING UP about my gravel bike journey

 “Getting the green light to build my dream bike wasn't all I imagined it would be.”  

I have always been more of a forager, building up bikes from other people's discards, as my reintroduction to cycling came at the same time as our first mortgage and a young family, about 35 years ago. Spending money on myself has always been hard. The stress of picking each and every component without boundaries was really getting to me and I could see my financier getting annoyed at the time I was spending on research.  

I had been initially talking to Dimitry at Triton about a custom Ti frame when I ended up chatting to Kashi Leuchs at Black Seal, the local importer for OPEN. I was Kashi's webmaster back in the day when he rode with Cadel Evans, Tinker Juarez and Christoph Sauser on the Volvo Cannondale team. This was my only source of fruity parts way back then; contra deals with Kashi. He offered me his demonstrator OPEN UP for a good price and my problem was solved or was it.... 

Outside the gun emplacements at Waimapihi

There were some issues. I wasn't a fan of many of the features that modern bikes come with out of the box. Internal cable routing, 1x, press fit BBs and sram hydro were all things I had managed to avoid up until then, or had bad experiences with previously. 

The first thing I did was to locate some left-hand shifter internals to turn it into a 2x. The good news is that Sram cable shifters are incredibly easy to work on, assuming you can source the replacement parts. A friend of a friend found some for me in Australia luckily. I replaced the rear 1x derailleur with a WiFli Force 2x variant, a road-link, an 11-42 cassette, and a 46/34 chain-ring combo on the front. Ideally an early model 10 speed exact actuation mtb derailleur from sram would have been great but the cable exit port position for the OPEN wasn't compatible. This was pretty common at the time, but I see a lot of the more recently designed bikes that support cable shifting have the cables exiting mid chain-stay rather than from the very endpoint of the frame which really “opens up” derailleur choice… 

Cheeky Quail photobombing at Waimapihi

Unfortunately, my next problem was chain derailment which happened a lot with the kind of riding I was doing, mostly trail riding, Cyclocross and some bikepacking. I got hooked on bikepacking in 2010 when Simon Kennett introduced the concept to Aotearoa after he did the 2008 Great Divide. I have only bikepacked on the OPEN UP a handful of times, two of them on the 800 km plus Renegades Muster, but I wanted the OPEN to be bikepacking capable if the course suited. The 2x set-up wasn't giving me low enough gearing on the steepest parts unfortunately the first time I did it. Common sense at this point would have been to go straight to Shimano GRX for the only clutched 2x system available at the time, but I was still persevering with the Sram ecosystem, and trying not to blow more money. 

 Ratio-technology from the UK had started building 12 speed upgrade kits for cable Sram shifters when it became obvious that Sram were not going to support the 12speed cable shifting at the time. Before long Ratio were also building extender cages for 1x sram derailleurs so I eventually went back to 1x and grabbed one of their long cages so I could shift into a 52 on the back if need be. I could have gone to 12 or 13 speed shifting with one of their replacement ratchets, but I stayed with 11 speed so I could keep my current wheels and installed a Garbaruk 11-50 cassette on the back. The lower gears were a big advantage with the type of riding I do. 

Ratio derailer extender cage.

Garbaruk 11-50 11 speed.

Being ideologically opposed to electric gears I still had one major beef with the OPEN's design. I hated the internal cable routing, having to remove the crank and BB just to replace a derailleur cable was not good for my blood pressure. Especially when the appropriate BB removal tool failed to budge the original creaking plastic BB. 

The fix came in two parts, a screw-together Wheels Manufacturing BB and full-length internal cable housing. The screw-in BB was effectively self-extracting with the un-screw, tap, un-screw, tap extraction method with a small rubber mallet. But to be honest, the BB shell does not need to come out now anyway, I just tap the bearings out if they need replacing. 

My next improvement came with the addition of some funky blue Growtac Equal cable brakes, at least the equal of my hydros, and when paired with Sram red cable shifters, a few grams lighter than the standard Sram Force hydros. I was super impressed with the brakes, the power, the light action, the adjustability, and the colour. My days of bleeding draggy brakes were over. I have been hammering these brakes for a good while now and really enjoy having the ability to adjust them on the fly if needed. It’s actually a feature, knowing if your brakes need adjustment, not something that you get a heads-up for with hydros which take up the slack automatically, until you hear that sound of metal on metal. The stock sintered organic pads last incredibly well. Normally I would only use sintered metal. 

Growtac Equal brakes paired with Sram Red. Light, strong, adjustable.

 When Growtac announced their new stepless (friction) drop-bar shifters on the Japanese domestic market I was lucky that a friend was in Japan and was able to snaffle me a pair. The ability to use any old derailleur or cassette with their shifters feels very liberating to me and so far, I have been very happy with the way they work. I really feel like they had me in mind when they came up with this concept. The levers are not unlike the Sram red cable levers I was using previously in that they are quite narrow, although the finish looks a bit like Campagnolo Ekar, and the inner shift lever also looks a tad Campy. Despite the hard edges on this inside shifter, it never caused me any issues with kit clearance or rubbing on my hands during the 4 days of the 830 km Renegades Muster. The shifting is surprisingly quiet, and you can adjust the amount of friction in the system. It is apparently possible to link up the left and right levers so you can shift up on one shifter and down on the other, I haven’t tried this, but Growtac show videos of it working.  

The initial set-up is a bit more complicated than a typical shifter installation because you are able to install different sized shifting drums, depending on whether you are using a road or mtb derailleur. I don’t know just how far the launch has gone in Japan or what the plans are internationally. I think the Japanese dollar might have had an effect. 

With the ability to run both 650b and 700c wheels on the OPEN UP I have a bike that can change from trail to commuter mode in minutes. It's not a cafe bike and gets a pretty hard time - mostly on the local trails on our weekend rides. To be honest it spends most time with the 650b wheels on as I have a bunch of old 26ers I tend to commute on. 

As mentioned I have done a couple of bikepacking events on the OPEN using different sized wheels each time, and I definitely prefer the 650b's. For bikepacking I throw on my dyno wheel, klite lights, B-17 saddle and aero-bars for the long days and go down on the front from a 40 to a 36-tooth chain-ring. For cross season the 700's go back on. 

Day 2 on the 2024 Renegades Muster

I've used 43 mm tires on the 700c wheels, although clearance officially maxes out at 40 mm. In 650b mode, 50 mm seems to be the max but you can go a lot bigger on the front. It's a shame that 650b has fallen out of favour but the difference in height between a 50 mm 650b and a 38 mm 700c wheel feels minimal, so I am always going to prefer that over a 700 c wheel that just gets taller or smaller depending on if you are running a 50 mm tire vs a 35 mm tire. 

I feel like the bike is pretty sorted currently. I could go back to 2x now that I have brand agnostic shifters but I'm probably just going to take the lazy option and go up or down on the front chain-ring sizing depending on what I am doing. 

I haven't ruled out externally routing the rear shifter cable housing for a better path, but with friction shifting, your gears are never actually out of adjustment anyway. 

The OPEN UP’s design is pretty old by modern gravel bike standards but somehow it still does a really good job of anything that I've thrown at it so far. I won’t be moving it on anytime soon. 

Details 

• Frame: OPEN UP generation 2 
• Shifters/levers: Growtac Equal Control stepless 
• Brakes: Growtac Equal 
• Rear Mech: Sram Rival with Ratio-technology SR52 cage 
• Front Wheel: Hunt 650b or Easton 700c or SP dyno hub in 700c with Stans rim 
• Rear Wheel: DTSWISS 650b or Easton 700c 
• Tires: Specialized Fastrak in 650b x 2.0/Raceking 2.2 or Rene Herse Barlow Pass  
• Cassette: Garbaruk 11-50, 11 speed or Shimano XTR 11-40, 11 speed 
• Cranks: Sram Force 
• Chainrings: 36 or 42 
• Pedals: Shimano XT 
• Seatpost: Thompson Elite 
• Seat collar: OPEN 
• Saddle: Specialized Power 168 mm or Brooks B-17 
• Headset: Cane Creek 
• BB: Wheels Manufacturing screw-in 
• Stem: Cheapie weener UNO 
• Bars: Ritchey Venturemax 

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