Jet Stream Road Fork
In these days of carbon-fibre-everything, it takes something a bit special to stand out from the crowd. Oval’s latest aerodynamic Jet Stream road forks certainly do that. They’ve evolved from last year’s time trial fork, with its distinctive ‘biplane’ construction. For the road fork, the straight legs of the time trial fork have been developed into a more traditional curved and tapered shape, but the ‘biplane’ aerodynamic design remains.
Pick up a pair, and you’ll see that the Jet Stream forks are amazing to look at, they’re really light, and they just ooze quality – well, they are made in Switzerland after all. The carbon fibre lay-up is really neat, the finishing is great, the dropouts are beautifully machined. But what are they like to ride? I put a pair on my road bike and put them to the harshest of tests – first on the UK’s potholed roads, and then on the smooth, sweeping descents of the Alps.
The Team Bit
A couple of Pro-peloton teams are using Oval odds and ends, by choice not sponsorship they hasten to add. Astana/Wurth would have been using them at the Tour if it wasn’t for last minute change of plans… and Vino and co have had most of their forks, bars, stems and TT bars on their bikes so far this season. Liquigas have equipped some their TT Bianchi bikes too (at the endorsement of Magnus Backstedt, who has been testing their stuff for several seasons). So they are establishing a impressive following amongst the pro riders.
The techie bit
Firstly, for all you weight watchers out there, these forks are pretty light. The manufacturers claim 425g, but according to my kitchen scales the pair I had weighed in at 410g (that’s before I cut the steerer tube down, and including the weight of the star-fangled nut thingy).
But weight isn’t what these forks are all about. The unique ‘biplane’ design is all about aerodynamics. It’s hard to explain in words, so have a look at the pics. According to Oval this design offers great advantages:
“It’s a fact—your bike’s wheels generate more aerodynamic drag than any other piece of equipment. And aerodynamically speaking, a road racing wheel is a mess. The exposed spokes and low-profile rims are terrible enough by themselves, but when you set the whole works in motion it becomes a giant turbulence generator. And turbulence, as any aerodynamics student will tell you, equals drag.
The drag is greatest at the top of the wheel, where the spokes’ forward motion means they rip through the air at twice the bike’s speed in still air. The R900 helps manage airflow in this critical area by directing this turbulent airflow through its slotted venturis, compressing this turbulent flow back into a smooth, laminar stream. What’s more, the airstream exits the fork in an outward direction, which helps strip the turbulent, drag-producing layer of air away from the spokes as they approach the fork blade and provide a further drag reduction.
Because road racing wheels aren’t as aerodynamically optimized as time trial wheels, the R900 can have an even greater drag-reducing effect than the A900, which is good for a 55-second advantage in a one-hour time trial at 50 km/h (31 mph). That’s just too much of an advantage to ignore.”
Unfortunately, the RCUK wind tunnel is presently broken and we can’t measure coefficients of drag just now, so we’ll take their word for it.
On the road
I wasn’t sure what to expect on the road. Although the forks are nicely curved and raked, the legs are quite thick from the front to back, and narrow from side to side. I feared a rather harsh ride and slightly vague steering. I was 100% wrong.
The Oval forks immediately impressed me with the way they cancelled out road ‘buzz’, softened the bumps, and steered with great precision. After I’d weaved around the traffic out into the countryside, they built on these great first impressions. No sign of flex under braking or when climbing out of the saddle – and that wonderful feeling of light precision as I swooped downhill. I found I could corner more confidently and faster than ever before.
Off to the Alps then. Same story. Whether it was grovelling up the Izoard, or flying down its hairpins, the Oval forks were excellent. They felt light and responsive on the climbs, and tracked really true round all the hairpins (even during emergency mid-bend braking to avoid idiot slow descenders). Equally important, they survived some rather enthusiastic baggage handling in Bristol and Geneva – so they should last a few years as well.
As for the aerodynamics – well, the only way I’ll be able prove the advantage would be to go back and ride the Etape again with my old forks – and after riding on these, there’s no way I’ll do that.