Short Fork Design (SFD) is featured on Rush Skate and Rush Pro Skate roller skis. Exclusive to Rundle, SFD is a novel design that increases roller ski stability without the drawbacks of common roller ski designs. Here are the three key reasons SFD is right for you:
Ankle stability is the most important component of roller ski performance. SFD dramatically lowers the roller ski geometry to reduce ankle strain and maximize control.
SFD only adds 6% weight to roller skis, giving you world class performance without a noticeable weight difference.
Torsional rigidity is essential for reliable tracking when applying side loads to your roller skis. SFD is very torsionally rigid to ensure predictable handling whether you're cornering, sprinting, or braking.
Short Fork Design FAQ
Why not lower the roller ski geometry by putting a bend in the frame?
There is a limit to how much an aluminum roller ski's geometry can be lowered by bending its frame because at a certain point bending damages structural integrity. With Rundle SFD, ground clearance is the only factor limiting how much the roller ski geometry is lowered. This means we can tune SFD roller skis to perfectly balance stability and ground clearance.
Short forks are really light, are they strong?
Rundle's short forks are extremely strong. We machine our forks out of 6061-T6 aluminum and have never seen one break.
Could you make a one-piece roller ski out of carbon fiber with the same benefits as SFD?
1. We're not convinced carbon fiber is a good material for roller skis, especially skate roller skis. Carbon fiber doesn't handle abuse well, and roller skis are by far the most abused category of Nordic ski equipment.
2. Carbon fiber is significantly worse for the environment than aluminum. Carbon fiber has a necessary performance advantage in some categories of Nordic ski equipment (like poles), but roller skis is not one of those categories.
3. We wouldn't be able to manufacture carbon frames in North America (all our SFD roller ski frames are currently made in Canada).
4. The price would be nearly double that of an aluminum version.
In summary, we could release a carbon fiber roller ski in the future, but for now we don't think it's worthwhile.