Ski Flex Profile Discussion

When you’re shopping for flex profiles, you see all kinds of vague terms such as “medium flex”, “soft flex”, “medium plus”, etc. What does that actually mean numerically?

In the book is “Skiing Mechanics” by John Howe, the chart says 30-60 N/cm typical stiffness for race skis in the footer note to the left – however – I have measured the deflection of the 6 factory made skis I have laying around – some race skis but some not – and they all fall within the range –

Rossignol experience 83 (168cm) – 40 N/cm
Head Mojo 80 john olssens (170 cm) – 39.2 N/cm
Fischer RC4 WCSL (165 cm) – 47.7 N/cm
Fischer RC4 WCGS (180 cm) – 39.2 N/cm
Volkl Supersport (154 cm) – 49.2 N/cm
Rossignol temptation 76 (146) – 38.1 N/cm.

I think the last pair I made came out too soft – they came in at 22 N/cm deflection. my testing apparatus:

and definitely softer than I calculated it would, but I’m waiting to see what my friend thinks of them – he’s lighter than me and beginner/intermediate so he may end up liking them.

I think the deflection range is intended to be more of a rule of thumb / engineering check than a rule to live/die by. I’d be willing to bet there are plenty of great skis outside the range.

The pair I’m working on now is 20oz fiberglass top and bottom with 2.5/11.5/2.5 core and 187 cm, no carbon (also for someone else) – I’m curious where this ski will fall on the scale – I calculated 60.7 N/cm but my calculations have been pretty off historically so we’ll see 

here’s the stiffnesses / specs for the ones I’ve made so far –

first pair (grey dyed oak carving ski) – 2/10/2 core – 22 oz fiberglass top/bottom – 1″ wide 373 gsm carbon stringers top/bottom – 66.7 N/cm

second pair (rosewood) – 2/9/2 core – 20 oz fiberglass top/bottom – 1″ wide 373 gsm carbon stringer bottom & “x” shapes top – 31.7 N/cm

third pair (stripes) – 2/8/2 core – 20 oz fg top/bottom – 1″ wide 373 gsm carbon stringer bottom – 22 N/cm