#102 LONI HULL’S STRUCTURE CYCLEWORKS SCW 1
A motorcycle-inspired enduro bike taking the concept of linkage forks further
Throughout the history of mountain bike design, certain themes keep reappearing, one of which is linkage forks. While telescopic suspension has its limitations, no one has yet created a mainstream-accepted alternative. Trust Performance created a buzz last year with their Shout and Message forks, but these had unusual ride characteristics and a high price, and the company have now suspended operations, citing the ongoing impact of the coronavirus pandemic.
Loni Hull, founder of Structure Cycleworks, believes that linkage forks haven’t taken off because to realise their full potential, they need to be integrated into the chassis of the bike. “It’s the only way to take full advantage of the benefits of axle path, dive reduction, bump compliance and stability,” he says. Loni, from Calgary in Canada, comes from a motorcycle-racing background where the concept of linkage forks isn’t so alien and big dogs like Honda and BMW already have them. We’ve seen attempts at integrating frames with forks in MTB – remember the Whyte PRST-1? – but Loni says his SCW 1 is the only bike currently on the market to do this.
“I wanted to call this bike the Troublemaker,” he jokes, “because the intention was to shake things up!” Loni’s ambition was to design an enduro bike that rode better than anything else. One with perfect front-to-rear suspension balance and none of the issues associated with conventional forks. He certainly achieved part of that goal, because the Structure SCW 1 has such similar leverage rates at the front and rear that it uses two identical DVO Topaz air shocks, tuned the same way, just with less air in the front.
As a traditional telescopic fork compresses, the head angle of the bike will steepen, shortening the wheelbase and pitching the rider’s weight over the front wheel, which isn’t what you want when riding at speed. On Loni’s WTF (Without Telescopic Fork) design, the linkage does the opposite, slackening the head angle from 66 degrees (static) to 59 degrees at full travel. The theory is that you get sharp handling at slow speeds but the bike becomes more stable when pushed deep into its travel. This means the rider can stay in a neutral position without feeling like the wheel is tucking under. The other benefits of the WTF linkage are small-bump compliance (pivoting on oversized sealed bearings, there’s less stiction than on a telescopic fork) and control over the axle path.
Loni went through an arduous process of modelling and prototyping. “We started with full-size mock-ups in steel and MDF (1) so we could analyse all the axle-path and steering-linkage variants,” he explains. “And then we made one in foam, with the idea of overwrapping it in carbon fibre to create a functional bike.” After analysing the prototypes with the help of Toronto-based bike design studio KQS, the first alloy test bike was made (2). This had eccentric inserts in the main pivots and shock mounts, allowing Loni and the Structure team to adjust the kinematics and explore different leverage ratios. “We were surprised how such small differences in position could make such big changes to ride feel,” he admits. Aware of the expense of re-tooling carbon moulds, Loni says they agonised over the details and went through perhaps 1,000 iterative drawings before taking the daunting leap to carbon fibre (3). “We reviewed everything from tyre clearance to carbon wall thickness at impact zones,” he explains. “But believe it or not, something that required more brain-drain than almost anything was cable routing. We must’ve modelled 50 ways to do it!”
The bike you see here is the result of that deliberation – a 650b-wheeled, 150mm-travel enduro rig, designed for the rugged trails of the Canadian Rockies, where Structure are based. As seems to be the norm with anything a bit different, when the brand revealed what they’d been working on at Crankworx Whistler in 2017, it was met with a lot of hate from internet trolls. Structure’s response has been to get people to actually ride the bike, and they’ve been organising demo days across North America. “Well over 95 per cent of riders come back with huge smiles,” Loni assures us, recounting a story about two racers at the Sea Otter Classic last year who demoed the SCW 1, then independently asked if they could borrow the bike to race on. “They both ended up on the podium,” Loni smiles. The SCW 1’s appearance isn’t for everyone, but Loni believes that preconceptions about how a bike should look are changing. “There’s a lively dialogue about innovation in MTB and I’m proud that Structure are in the thick of it,” he says. As you read this, the team are back at the drawing board working on long- and short-travel 29ers and an e-bike, all with the WTF linkage. Whether the SCW 1 is a glimpse of where bike design is heading isn’t clear, but either way, Loni and Structure are pushing the boat out.