Wheels

[John B.]

I had always assumed that lighter wheels were faster but I have been
reading recently that wheel weight, in the amounts usually encountered
in bicycle wheels is largely superficial and the aerodynamic factor is
far more important, thus the common "carbon wheel" is normally heavier
but being more aerodynamic is faster.

Since the wind resistance does increase by the square with doubled
road speed this does seem reasonable, but sometimes what seems true
isn't what things actually feel like in actual use.

Has anyone gone from light weight aluminum alloy rims to carbon rims
which are more aerodynamic but heavier? And if so what has your
experience been.

I suspect that on a, say 10 mile time trial, the carbon rims might
prove beneficial but how about on a, say 50 mile "Sunday ride"?
--
cheers,

John B.

[DATAKOLL MARINE RESEARCH]

a few grams on the front is feelable ....centripetal force known or felt as gyroscopic...loose engineering but that's the feel.

carbon wheel$ wear out

internet is prob replete with mudslinging n various forms of engineering data that I will not look for.......

[Graham]

"John B." <slocom...@gmail.xyz> wrote in message news:6jmlvbdn03hp17t2f...@4ax.com...

As you say the time diffeence on a TT is measurable but on a Sunday ride then it really depends on the wheels whether I can tell the difference. I have standardised on Shimano wheels for TT, summer events, and summer training and those are Dura Ace C50, Dura Ace C24 and RS80 C24. The C50s are measurably faster than the C24s for TT. Also for TT I put disc covers on the rear C50 which increases the weight but the bike is again measurably faster due to the further improved aero.

The DA C50s weigh 1670gms, DA C24 1380gms and RS80 1530gms.

I will choose the DA C50s for relatively flat spoertives and the DA C24s for tackling events in the Alps, Pyrenees or Dolomites. Based on my TT experience I "believe" (no comparative data) that the lighter wheels benefit me on the long relatively steep climbs and as I will be needing to brake on the descents aero is a lot less important whereas where there is the opportunity for some long relatively flat fast cruising I go for the DA C50s to take advantage of the better aero.

That said I would not claim to be able to tell the difference between these wheels on the summer bike on a 50 mile "Sunday ride" when they all have the same tyre and tube combinations on.

I can however tell the difference going the other way. If I have my winter training wheels on which are Open Pro rims on Ultegra hubs. These weigh in at 1880gms. The bike definitely feels more sluggish. In this case the wheels are both heavier and less aerodynamic than any of the Shimano sets. On of the big differences is the spoke count and type. The Open Pros are 32/32 standard whereas all the Shimanos are 16/20 bladed. This affects both the weight and the aero.

Graham.

---
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[DATAKOLL MARINE RESEARCH]

Spiff !

graham, switched from round to aero spokeson same rim/tire/bike ? Results ?

Subjective results carbon-metal 50 miles patchy road surface ?

[Frank Krygowski]

I've never used carbon wheels, but I did something similar once, long
ago. As a birthday gift, I was given a set of spoke covering wheel
discs. They were nylon fabric stretched over an aluminum hoop, with
clips that fastened them to the spokes.

I was pretty enthused because I'd attended a Human Powered Vehicle (AKA
streamlined bike) workshop where the presenters demonstrated the aero
benefit. Spokes really do churn the air a lot!

Anyway, I installed those on the rear wheel of my (then) only bike, the
one I used for commuting, touring, time trials, etc. In those days, most
of my rides home from work were treated as time trials. I recorded the
times and killed myself trying to go fast.

Suffice to say I could never detect a difference in those times, nor in
the way the bike felt.

This doesn't mean the discs didn't help. Indeed, I did install them for
a while when I did a time trial or a century ride, because I was sure
they made _some_ difference. But the difference certainly didn't change
the riding experience. Ultimately, I just stopped using them.


--
- Frank Krygowski

[Doug Landau]

How is it that carbon rims are more aerodynamic?

[Lou Holtman]

They are not by default but you can get a more aerodynamic rim with less
weight penalty. That is the whole deal.

--
Lou

[Benderthe.evilrobot]

"Graham" <h2gt2g42-mi...@yahoo.co.uk> wrote in message
news:ntfno2$17oi$1...@gioia.aioe.org...

Unless you're going all out to save weight on anything you can, the only
significance of wheel weight is; "unsprung weight" if you have suspension.
And probably then, only if you have proper damping such as you'd find on an
engined vehicle.

[James]

A pair of Zipp 404 wheels are both light and aerodynamic.

Whether weight is an issue for you, is whether you have many hills and
how steep? In a race sprint, I'd want both aero and light.

--
JS

[Gregory Sutter]

On 2016-10-10, Doug Landau <doug....@gmail.com> wrote:
>
> How is it that carbon rims are more aerodynamic?

For some years now, all the aerodynamic innovation has been
on carbon rim design, rather than alu rim. The carbon material
is also more amenable to producing the dimpled design that seems
to be more aero than a smooth surface.

http://www.zipp.com/technologies/aerodynamics/ablc.php

--
Gregory S. Sutter Mostly Harmless
mailto:gsu...@zer0.org
http://zer0.org/~gsutter/

[cycl...@gmail.com]

On Sunday, October 9, 2016 at 5:21:54 PM UTC-7, John B. wrote:

Because in time trials there is almost no climbing the older heavier Campy Shamals and the like are noticeably faster and considerably cheaper than the carbon wheels which have a limited lifespan.

[cycl...@gmail.com]

I have a set of very light Campy Neuron wheels which are more or less standard aluminum wheels. I also have a set of Campy Atlanta aero wheels which are considerably heavier. The Atlantas are noticeably faster everywhere.

[John B.]

Which brings up another question. Is the main factor causing "wheel
drag" the rim itself or the spokes, whether configuration or number?
If one had a non aero rim but flat spokes (which have been shown to
cause less drag) what would the total "wheel drag" be in relation to
an aero rim with conventional round spokes?

Could one take one's old clunky aluminum rims and re-spoke with flat
spokes and achieve something with less drag? Significant enough to do
it?
--
cheers,

John B.

[Frank Krygowski]

On Friday, October 14, 2016 at 8:10:23 PM UTC-4, John B. wrote:
>
> Could one take one's old clunky aluminum rims and re-spoke with flat
> spokes and achieve something with less drag? Significant enough to do
> it?

Many years ago, I installed oval spokes on the front wheel of one bike. Before
doing so, I timed the wheel's time to spin down from (IIRC) 20 mph to zero
with the bike supported in the workstand. I compared that time with the new
spokes, figuring that the only decelerating force was spoke aero drag. (Well,
and skin friction on the tire and rim, which would not change.)

I was somewhat amazed that the wheel coasted down faster with the aero spokes.
And of course, I was s bit disappointed. Of course, I never detected any
difference either way when riding.

As described before, I used to be very interested in bike aerodynamics.
I did find a few things that make a noticeable difference. Those are:
1) Avoiding really floppy clothing; 2) aero bars. 3) when touring, panniers
with minimal frontal area; 4) if you really want to get into it, a Zzipper
windshield.

Everything else I tried (oval spokes, wheel covers, aero water bottle,
aerodynamically shaped panniers and/or handlebar bag, etc.) may have made a
difference that was measurable in a wind tunnel, but they had no effect on
the riding experience.

YMMV.

- Frank Krygowski

[John B.]

I agree with you. In fact on one particular slope on a route I ride at
least once a week you climb up a long hill and than there is a very
moderate down hill slope, about a kilometer, to the village street. If
you crest over the top and give two or two vigorous pedal strokes and
you can coast the rest of the way at a pretty constant 35 kph. I've
found that the difference between riding on the tops and the drops is
about 1 kph. Drop down and the speed increases sit up and it drops
off. Back down and it picks up again.

My view on wind resistance is much the same as weight. If I have a
choice I will pick the lighter component and if I could change spokes
and pick up 1 kph I'd do it.

While it is, as you say, probably futile for the normal cyclist to
worry about but I suspect it is a more logical subject that the usual
subject of "if you ride a bike and if you have an accident and if you
hit your head and if you are wearing a helmet... it might help" :-)
--
cheers,

John B.

[John B.]

On Sat, 15 Oct 2016 13:46:00 +0700, John B. <slocom...@gmail.xyz>
wrote:

As an addendum to the question of aerodynamic drag see
http://tinyurl.com/j9ov9wv

[Graham]

"John B." <slocom...@gmail.xyz> wrote in message news:b6j30cdvu5j9lk98h...@4ax.com...

Zipp has put out a series of notes on wheels including spoke count, spoke shape and rim shape which might help:

http://www.aeroweenie.com/assets/backup/zipp_data/spokecount.pdf
http://www.zipp.com/_media/pdfs/technology/spokeshape.pdf.bak
http://www.zipp.com/_media/pdfs/technology/rimshape.pdf

The second link as an additional .bak extension which I removed after downloading the file to open it as a standard pdf.

There is also some now relatively old data at:

http://www.aeroweenie.com/assets/img/data/roues.jpg

and more general stuff at:

http://www.aeroweenie.com/data.html

The consensus seems to be that spoke shape is far more impoortant than number. If the wattage gains of moving from 32 round spokes to 18 aero spokes quoted by Zipp are real then you should definitely notice a difference by simply replacing the round spokes in your current wheels. Sapim C-Xrays seem to be the favourite. Those are what are in all my Shimano wheels. I weigh between 75-80kgms depending on time of year and despite the fronts only having 16 spokes the wheels have remained true with no breakages and my training set is getting close to requiring a rim replacement. When I first bought the wheels I was concerned by all the horror stories, some in this group, about low spoke count wheels so I bought a couple of spare spokes one of each length used in the fron t and back wheels and taped them under my top tube. Needless to say that is where they have remained ever since - around 5 years!!!

[cycl...@gmail.com]

My comparison is between the top of the line Campy Neuron al wheels compared to the older Campy Atlanta wheels.

There are two major differences: 1. The hubs - the Atlanta uses the older Campy Record huhs that do now have sealed bearings. and 2. The Neurons have aero spokes.

The Atlanta's are noticeably faster and I expect that is because they do not have sealed bearings. All of the wheels that I've looked at that have sealed bearings ALL run down much faster than the older hubs with open bearings.

The aero spokes are NOT a good idea. They are very costly and especially on modern wheels with fewer spokes they tend to break more often.

[cycl...@gmail.com]

When I "came too" from my concussion after two and a half years, the hair on my legs was so long I actually had to tuck it into my socks. I shaved for the first time then. But what is really bothersome is that if you shave once you get "stubble" for quite awhile before the hair gets long enough to stop bothering you when you're wearing pants.

I suppose that there's reasons for racers shaving their legs but not for a sport rider.

[cycl...@gmail.com]

The initial chart showing 2 mm of deflection at some 125 Newtons is a good one. A Newton is an acceleration of one kg to 1 meter per second sq.

That is a force that no one here could corner at without crashing.

So from that I would estimate that you or I couldn't deflect any low spoke count wheel more than 1 mm or so little as to be no problem.

As for rim shape the first document has to be renamed from being a .bak file then it will open. But the Zipp rim data shows that pretty much all of the modern aero rims are similar in drag so that unless you're riding a TT is doesn't matter.

The file on the aero bike frames is simply too much trouble to bother with. I'm not a racer and never will be again.

So my Atlanta 1996 wheels really are significantly faster than my Neuron wheels as it felt. But I sure as hell am not going to pay the sort of money it would take to get a set of Zipp wheels.

[Sir Ridesalot]

Shaved legs = easier for massages and easier for cleaning out road rash debris. Also, recent research shows that shave legs are a bit more aerodynamic.

Cheers

[John B.]

I think that you are one of us "old geezers" who have aged enough to
have achieved the ability to think for our selves but for some of the
younger generation looking "cool" is reason enough for doing anything

[James]

On 20/10/16 05:09, cycl...@gmail.com wrote:

>
> My comparison is between the top of the line Campy Neuron al wheels
> compared to the older Campy Atlanta wheels.
>
> There are two major differences: 1. The hubs - the Atlanta uses the
> older Campy Record huhs that do now have sealed bearings. and 2. The
> Neurons have aero spokes.
>
> The Atlanta's are noticeably faster and I expect that is because they
> do not have sealed bearings. All of the wheels that I've looked at
> that have sealed bearings ALL run down much faster than the older
> hubs with open bearings.

Losses in cartridge bearing seals, while they may appear significant if
you spin the wheel and estimate based on how it slows, is usually
insignificant in practise.

IIRC, at 50km/h each sealed cartridge bearing in a hub might consume
about 0.5W total, and 0.4W of that is in the seal. If you can notice
the difference of less than a couple of watts (for both wheels), you are
far more sensitive than most.

>
> The aero spokes are NOT a good idea. They are very costly and
> especially on modern wheels with fewer spokes they tend to break more
> often.
>

Actually, aero spokes are not a terrible idea, provided you use enough
of them that the wheel is reliable. The initial cost difference on a
wheel might be $40, but the wheel will be more aerodynamic.

I think the reason the Atlanta wheels feel faster to you is because the
rims are quite aero compared with the Neutron rim.

Atlanta rims are heavy, but once that weight is moving, on the flat at
least, it does not hinder.

Atlanta rims: 590g, 19mm wide x 34mm deep.

Neutron rims: 20mm wide x 18mm deep

--
JS

[Graham]

<cycl...@gmail.com> wrote in message news:ad3d6c04-400b-440a...@googlegroups.com...
[Snip]

> The aero spokes are NOT a good idea. They are very costly and especially on modern wheels with fewer spokes they tend to break more often.

That is not my experience. As I mentioned in earlier posts in this thread I have been riding three sets of Shimano wheels all with 16 front and 20 rear aero spokes for over 5 years now. In that time I have averaged about 7500 miles a year at least 50% of which has been on one of those sets which I use as Summer training/leisure riding wheels. The other two sets I reserve for TT and other competitive events. None of those wheels have had a spoke failure and none have gone out of true. Having heard the horror stories, I took the precaution to tape a couple of spokes under my top tube when I got the first pair and there the spokes have remained.

In the mean time,around 40% total mileage, I have had spokes fail in my Open Pro 32 spoke winter training/leisure riding wheels. All were elbow failures.

I think the two main differences between the standard spokes in the Open Pros and the aero ones in the Shimanos are the material specs and the fact that all the aero spokes are straight pull.

[Frank Krygowski]

On 10/20/2016 4:51 AM, Graham wrote:
>
> <cycl...@gmail.com> wrote in message news:ad3d6c04-400b-440a...@googlegroups.com...
> [Snip]
>> The aero spokes are NOT a good idea. They are very costly and especially on modern wheels with fewer spokes they tend to break more often.
>
> That is not my experience.

Nor mine. It's been decades since I tried aero (actually oval) spokes.
The oval spokes I tried may not have been super-aero, since they didn't
require any modification of the hub's holes. But I never broke one.
(Of course, this was back when my wheels had 36 spokes and took 27" tires.)

--
- Frank Krygowski