Wheels

On Wednesday, October 19, 2016 at 2:17:41 PM UTC-4, wrote:
On Friday, October 14, 2016 at 11:56:03 PM UTC-7, John B. wrote:
On Sat, 15 Oct 2016 13:46:00 +0700, John B.
wrote:

On Fri, 14 Oct 2016 17:45:00 -0700 (PDT), Frank Krygowski
wrote:

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 a
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

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" :-)


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

:-)

--
cheers,

John B.

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.

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

On Wed, 19 Oct 2016 11:17:33 -0700 (PDT), wrote:

On Friday, October 14, 2016 at 11:56:03 PM UTC-7, John B. wrote:
On Sat, 15 Oct 2016 13:46:00 +0700, John B.
wrote:

On Fri, 14 Oct 2016 17:45:00 -0700 (PDT), Frank Krygowski
wrote:

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 a
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

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" :-)


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

:-)

--
cheers,

John B.

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.

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
:-)
--
cheers,

John B.

On 20/10/16 05:09, 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

wrote in message ...
[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.

Graham.

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On 10/20/2016 4:51 AM, Graham wrote:

wrote in message ...
[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