I know this subject gets touched upon in paddle recommendation threads, but I’d be interested in seeing it addressed and argued directly.
Is flex in a paddle shaft or blade a good or bad thing? Why or why not?
I think facts and opinions on this question can come from many perspectives: physics, logic, racing experience, tripping experience, day paddling experience, medical or injury experience, aesthetics, subjective preference, or just simple emotion.
I’m interested in comments re both wood and composite paddles – single blade or double blade – and whether the flex is better or worse or the same if it’s in the shaft vs. the blade.
A hard topic to address quantitatively
– Last Updated: Jun-02-12 1:05 AM EST –
Some flex is good, not enough flex is bad, and too much flex is bad. This is true of all sorts of things, even gymnasium floors and bicycle frames, but how does one define the "right" amount of flex? Even farm tractors need some "give" in the system to avoid drive-train breakdowns in the long run (that "give" is provided by avoiding the use of too much weight for traction, so the tires slip an amount which is visually imperceptible when pulling a load, but that slight cushion of tire-slip is all it takes to reduce stress on gears and bearings). Same is true for the human body - a little "give" in the system saves wear and tear in the long run. However, too much "give" reduces the effectiveness of energy transfer, like if you were to pave a running track with the material used for wrestling mats. At the opposite extreme, no one would EVER pave a running track with concrete. Energy transfer would be good, but at the cost of discomfort and injury. It might even result in slower running speeds due to the comfort factor (that'd be interesting to find out, huh?).
I recently asked a question about making a new paddle blade stiffer. I thought the shaft and blade of the paddle it replaced was about perfect, though I can't describe why. In the new paddle, the blade is too flexible and I CAN describe why. It "springs back at me" when it accidentally strikes a rock, and it has a very pronounced BUZZ when doing a no-load underwater slice.
With "some" flex, the little bit of "give" in the paddle "gives that energy back" as it straightens at the end of the stroke during that moment when the force applied by the paddler tapers to zero, so I doubt there's much loss of efficiency, and the cushioning effect on the joints is valuable.
I think the "right" amount of flex is visible if you look for it. The oars of my guide-boat flex enough to be easily seen because they are quite long, and I can also feel how that flex pushes back on the water when they straighten at the end of the stroke as my effort is reduced. Somewhere on Flickr I have a photo of me "applying the brakes" while diagonally surfing a tiny wave in a canoe. The paddle I was using is one of my stiffer ones, but the photo shows a pronounced bend, much more curvature in the shaft than I ever would have guessed was there, even though it really isn't possible to put much more load on the blade than what was being done at that moment (on account of blade slippage in the water). That paddle sure doesn't feel too flexible when I use it though.
http://tinyurl.com/7bwk9uy
(For those unfamiliar with Flickr, select "Actions" at the top left corner to enable the viewing of different sizes).
For once I have no scientific or logical evaluation of something that seems "right" to me. It's all a matter of how it feels.
By the way, my paddles and oars all are made of wood.
Don’t see a benefit from flex
I have some full carbon and wooden paddles with flex that do “spring back at the end of the stroke” and to be honest I see no good use for that kind of behavior. At the end of the stroke I don’t need power - I’m taking the paddle out. When I need power is in the beginning and I do not want to lose that in flexing. I have stiffer paddles and they feel better to me.
The above is when I paddle hard, either forward on flat water (for distance/speed) or in white water (maneuver, surf). I do not want flex in these situations - I want precision and a direct response.
On the other hand, if I were to paddle in a very relaxed way, the paddle would not flex due to the lack of power applied to it. So, again, no benefit here…
I can’t say if flex helps with joints or not. If I’m paddling hard I’m straining my joints anyway, and as mentioned, the water has enough “give” already. If I’m paddling easy, I’m not putting enough strain on the paddle or joints to matter…
Suppose, some flex could feel like a good thing to some, picking-up small peaks in “straining” while paddling, but I don’t think it is good for efficiency or would have much of a benefit if any with good paddling technique.
From an engineering prospective, having some flex in the paddle would allow it to be built lighter while maintaining enough strength. And lighter is better for paddling, so that’s a benefit…
Actually, ZRE flex shafts are heavier
"From an engineering prospective, having some flex in the paddle would allow it to be built lighter while maintaining enough strength. And lighter is better for paddling, so that’s a benefit…"
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ZRE manufactures their flexible shafts a different way – by substituting some linear fiberglass on the inside of the shaft tube for some carbon. Hence their flexible shafts end up a slight bit heavier than their all carbon shaft.
Bad
in my estimation
Jack L
Depends: Young or Old Paddler?
The young prefer stiff and the old prefer flex. That’s the way it has always been and will always be. Start out stiff and eventually switch to flex many years later. Well, that’s been my experience with competitive surfski racers over 60 years old who have given me their stiff double blade shafts for more flexible and shorter shafts. The blades are still stiff though. The marathon surfski paddlers prefer the more flexible layup shafts, but prefer stiff for sprints and shorter races. For me, I don’t miss many bumps using a stiff and shorter shaft in “Victory at Sea” ocean conditions.
Maybe more “fun” with flex
– Last Updated: Jun-02-12 11:17 PM EST –
Right, I have been using a couple different carbon crank kayak paddles, and bought a BB crank with an aluminum shaft and plastic type flex Slice blades. My intent was to keep it as a backup, but it has turned out to be a favorite for paddles of a couple of hours or so. Reason is because it just feels like "fun" when I am paddling with it, and I wish I could explain it better. I guess I'm still puzzled by this, or maybe I'm just getting old>
I’ve used mainly ww slalom paddles
for the past 20 years. All the c-1 slalom paddles I’ve used have had a modest amount of flex, usually distributed between the blade and the shaft.
I believe slalom paddlers, particularly c-1 paddlers, want and expect a bit of flex, and as they should know what works, I accept their judgement.
It seems to me that for slalom kayaking, less flex might be needed, and my one quasi-competition kayak paddle is stiffer, but not rock hard stiff. It has an aluminum bent shaft.
I started canoe paddling with either Clement (mainly yellow spruce) or Norse (FG over aluminum) paddles, and they were all stiff. I knew at the time they were too stiff, but I did not like the alternatives.
Some criticise carbon shaft paddles as stiff, and tout wood shaft paddles. In my experience, it is not easy to build a flexy wood shaft paddle that will stand up to whitewater stress. I have made one solid ash, 5 degree bent shaft paddle where the shaft has been bulletproof. As for carbon shafts, if you need them flexible, the makers will probably supply them that way. Between the blade and the shaft, my Mitchell slalom paddle is as flexible as one might want, no more.
General question, but my specific case
I meant the topic to be general because I think the issue is not specific to single or double blades or to any particular type of paddling.
My specific situation is a recreational, non-racing, single stick open canoeist. I’ve had a 48.5" Zav flexible shaft bent paddle for five years and like the small flex better than the rigid shaft, which I had originally.
However, I just got a 57" flexible straight shaft and I’m not sure if it’s not too flexy at that longer shaft length. It feels just fine on long flatwater workouts, but it sort of feels too flexy when doing some powerful strokes during upstream attainments in current. Maybe that’s just subjectively relative to my old WW paddles.
G2d, I recently picked up my 30 year old Ilead mega-blade and can’t believe I used to paddle WW with that thing.
I don’t know. I’ve always had and loved wood paddles, and all good wood paddles flex to some degree. For those who say flex is bad in carbon, what did you say before carbon? You didn’t deliberately choose a heavy hardwood paddle just to reduce flex, did you?
Then there’s the ambiguity of the whole energy loss, phase shift, and spring back arguments. How much does the paddle really flex on entry – a fraction of an inch? How much energy does that really lose (or, rather, store as potential energy)? When does the paddle spring back releasing the stored energy? Some say at the end of the stroke where it’s useless. Really? But I’m almost always doing a correction at the end of my strokes, so wouldn’t spring back at that time help jolt my correction?
Does anyone really understand the store-and-spring-back physics for kayak stroking, wing stroking, switch stroking, correction stroking, rolling? Very murky to me.
Yes, but that’s for cost savings
most likely… I might be wrong, not familiar with their construction options.
Yup, murky!
That’s the problem with this discussion - we are all guessing and going by feel and what feels good to one is not good to another -
And yes, depends on the application.
Certain amount of flex could serve as a gauge as to how much power one is to apply: if it flexes too much, then one is paddling harder than the paddle is meant to be used. So that feedback can modulate the stroke over time…
As for the flex “storing” energy, that would only work if one maintains strong enough pull on the paddle while the flex is there and also maintains proper position while the paddle releases that flex. I find that rather difficult to execute without wasting the “stored energy” or my paddling momentum. Often, the flex just disappears somewhere during the stroke and not at the right time, especially during maneuvering strokes where it is even harder to “manage” that “stored energy” to a point where it is release to good use and not to just pull your hand forward when you are not pulling back (e.g., that energy is now lost and not transferred to the water).
Did someone mention impact?
In rocky or shallow water I like some flex to cussion the shock when stab the unexpected rock.
That was me.
However, I think a good amount of flexibility is actually so slight that it’s difficult to detect, except perhaps by comparing to another paddle that’s stiffer. My stiffest paddles, with no perceptible (to me, during normal use) flexibility clearly have more ability to bend than I expected, as shown by the photo mentioned earlier, but they don’t do anything uncomfortable when stabbing a rock. However, my newest paddle, which is too flexible, makes the rock feel “alive”, like stabbing a big carp that reflexively darts off upon paddle contact (anyone who’s done that knows what I mean). I don’t like a rock to feel like it hits back!