Bicycle Mechanics - Disadvantages to Oval/Bladed Spokes?

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calamarichris
07-09-10, 01:53 PM
What are the disadvantages?
The good folks who offered guidance on my previous wheel building thread seemed hostile to them, without offering reason. And the only reasons Jobst (love that name almost as much as "Horst") recommended against them in his book are:
a) hub must be filed for the spokes to fit through, and
b) twistage aligns the flat spokes in a non-aero configuration.
Contrary to the advice of many, I just built up a set of Velocity Fusion 32-spoke, two-cross, with Dura Ace hubs and Sapim CX-Ray spokes.
a) The spokes fit snugly through the hubs with no filing needed.
b) Using this DT tool, I was able to tension & true with absolutely zero residual twist. Whenever I tuned up wheels with round/butted spokes before, I would always get a plinking when taking them for a test ride; zero plinking with these babies.
http://www.wheelbuilder.com/store/images/D/dt_bladed_sp_holder_detail.jpg
So are there any remaining disadvantages? As far as I can tell, the only ones are:
a) these CX-Ray spokes are overkill for a 32-spoke wheel because they're built stronger for aero-wheels with lower spoke count.
b) it's a PITA to carefully install and hold the above spoke holder before making even minor adjustments to the nipple. (I suspect this is the real reason seasoned wheelbuilders are hostile to bladed/oval spokes.)
I assumed that having twisted spokes was probably a bad thing. Not so?
It seems like most old time wheelbuilders disagreed or told me I was wrong at just about every choice I made when building these wheels, but the wheels seem quite sturdy, and 32 oval spokes are certainly going to be more aerodynamically efficient than 32 round (& twisted:D ) ones. Since I have access to an identical pair of these wheels with Ultegra hubs and round/butted spokes, I'll provide test results, using Garmin GPS and SRM power meter later this month.)
Apart from the occasional issue of spoke hole fit, the rest is mostly about misplaced effort in optimization I suspect. A rider has to be going quite fast before the bladed spokes start being a significant advantage, and if you aren't going that fast you've just spent unnecessary money, and maybe compromised the strength of the hub flanges for little to no tangible benefit.
calamarichris
07-09-10, 02:19 PM
Thanks for the tip. It's true that I'm a 41-year-old slug who can barely ride a 5-hour solo century (perhaps it will be easier now with the aero spokes?),
but how did I compromise the strength of the hub flanges if I didn't file, cut, or discomfort them in any way?
mrrabbit
07-09-10, 02:38 PM
With certain rim and hub combinations you could find yourself with a wheel that has characteristics that lead it to resonate to certain frequencies while riding.
I had a radial front once that used ovalized spokes on a box section clincher with a Suntour Cyclone hub - I ended up with a really irritating semi-high frequency whistle or hum=8- once I got up to about 13-15mph. Being half-deaf - believe me when I say that I heard it and got tired of it after awhile. Others around me could hear it from from quite some distance.
As to hub/flange damage - some oval and bladed spokes are designed to be used in standard 14g drilled hub holes without modification. As long as that's what Mr. IHAVEASTRANGEHB7900 used, no worry.
(Did that just for a laugh...)
=8-)
I did say "maybe compromized" . If you didn't need to file, then that part obviously don't apply to you.
And don't get me wrong, I'm not judging. Most of us have bicycles and riding as a hobby, and questioning hobbies rarely hold up very well.
If you want bladed spokes and have the money to spend, well fine, go ahead - enjoy them.
In the larger scale of things they're probably on par with amateur riders upgrading to Ti bolts, ceramic bearings or shaving arms and legs - all of which that some people swear by and other people can't be bothered with.
calamarichris
07-09-10, 03:16 PM
I had a radial front once that used ovalized spokes on a box section clincher with a Suntour Cyclone hub - I ended up with a really irritating semi-high frequency whistle or hum=8- once I got up to about 13-15mph. Being half-deaf - believe me when I say that I heard it and got tired of it after awhile. Others around me could hear it from from quite some distance.
=8-)
When you tensed/trued that wheel, did you have a bladed spoke holder? Perhaps the diagonal orientation due to spoke twisting is what caused the whistle? These wheels are quieter than a church mouse. A dead church mouse; from Helen Keller's perspective.
svtmike
07-09-10, 03:22 PM
I just rebuilt my PowerTap wheel using DT Swiss Aerolites and that same tool shown in the OP. I didn't find the tool difficult to use at all, and the wheel came out just fine. I liked the bladed spokes because I could make sure they didn't twist. The wheel's got about 300 miles on it so far and is still true so I think I did an OK job building it.
I don't see the twisting as a problem at all. I hold all spokes, other than 2 mm straight gauge, when approaching high tension. On bladed spokes I use a small crescent wrench.
The disadvantages are higher weight and cross wind stability. Both will vary greatly with wheel design.
I rode deep profile bladed spoke "aero" wheels exclusively for two years. But after building some light 32 spoke 3-cross wheels the aero wheels have been hanging on the wall except for time trials.
If you want light and aero you're talking multi-thousand $$, more than most of us will want to invest for everyday wheels. I choose light.
I have a set of wheels with bladed spokes (Mavic Aksium). I immediately noticed that they tended to jerk the bike around a little in cross winds. Going downhill fast, they never felt super comfortable to me because of that. I switched to some wheels with conventional round spokes but a little deeper rim (30mm vs. about 20mm, I think). These wheels seem to me to be much more stable and I never even think about the cross wind issue like I did with the others. They seem more stable down hill too.
I'm just an old, slow recreational rider though, so ymmv, of course.
mrrabbit
07-09-10, 04:29 PM
When you tensed/trued that wheel, did you have a bladed spoke holder? Perhaps the diagonal orientation due to spoke twisting is what caused the whistle? These wheels are quieter than a church mouse. A dead church mouse; from Helen Keller's perspective.
These were slight ovalized...I was just the victim of a bad combo - that's all. A CAT1 racer I used to try to keep up with noted back then that I wasn't the first to have this happen. I.e., he'd heard about this kind of thing before.
Just a few weeks ago I spun the rear wheel on a carbon bike with carbon rims on carbon shell freehub equipped hubs - sounded like a freaking fire cracker rope going off on Vietnamese new year. Can't believe folks can tolerate that - maybe it's more muted when the wheels are on the ground.
=8-)
calamarichris
07-09-10, 04:55 PM
Yeah, those carbon rims give any drivetrain irregularity a bullhorn. I just got a set of the Dura Ace C50 clinchers last month and they're great for making sure the micro-adjustments to the rear derailleur are made.
badamsjr
07-09-10, 10:18 PM
I agree with Al1943 and Camilo: I have Mavic Ksyrium Elite's with bladed spokes, and they are much more subject to crosswind push than my Cane Creek Aeroheads with round spokes.
BCRider
07-10-10, 12:37 AM
I haven't tried any actual wider bladed spokes but I'd done about 5 sets of wheels with oval rear spokes. No issues at all with any of them. And certianly no ghostly howling or other odd whistling sounds. I'd happily use oval butted spokes again without a single worry.
daven1986
07-10-10, 01:37 AM
I have used elliptical spokes on my first wheel build - was a rear wheel so shouldn't affect stability in a crosswind. I found that they didn't twist so required no adjustment after stress relieving and they were easy to use. Obviously they are different to proper bladed spokes but they worked for me, they were also very cheap :)
calamarichris
07-11-10, 06:01 PM
Forrest Bump.
So some have cited whistling and crosswinds as possible disadvantages. Are there any other?
Not to dismiss those disadvantages, but neither appear to be an issue for my build at all.
And if there's anyone who's ever felt the inclination to build your own wheels, I'd encourage you to do so. Yesterday's ride which included sprint up some hills to test the stiffness, and a stiff crosswind at the beach were one of the most gratifying experiences for me ever.
I built my own wheels! And they work!
Any other disadvantages?
mrrabbit
07-12-10, 01:30 AM
One more disadvantage or issue:
Replacement spokes. You can't assume the average LBS will carry ovalized or bladed spokes.
And if they do - you can't assume they'll have the correct size.
So it is probably wise to have a couple extra for the front - and 4 for the rear already sized and stashed away at home or in the glove box of the car.
Some will say - "Tape 'em to the seatstay or chainstay!"
Break one - it's as simple as hitting the nearest LBS and providing the spokes for them if you are on the road.
=8-)
I'm not a fan of wide blades that require slotted hubs, but ovals and small blades that fit through round spoke holes are fine in my book. There's the PIA factor that they twist, but that's also a plus because all spokes twist but these show it and that's actually a benefit in disguise.
calamarichris
07-15-10, 12:18 AM
One more disadvantage or issue:
Replacement spokes. You can't assume the average LBS will carry ovalized or bladed spokes.
I believe you're asking for trouble to expect an average LBS to carry ANY spokes. Even my most curmudgeonly LBS who has a spoke thread-rolling die only carries one kind of spoke. And he's fully aware of his rareness, even if nobody else is.
I ordered a few spares, but if I were in your 'out-of-town-on-tour-with-a-broken-spoke' scenario, I could still use a regular or swaged spoke of the same length to get me home where I can order the correct length & profile from this keyboard.
I just wouldn't count on an average LBS to carry the length I need, round, butted, bladed, or otherwise.
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