Aero rims and spoke count

jim beam wrote:
wrote:
Hi All,

I still haven't won lotto yet, so I don't think some Zipp 404's or
similar wheels will be in my x-mas stocking this year, so I am thinking
about lower cost options.

I have some nice everyday wheels, so I am looking into "race" wheels to
be used in club races, club TT's, and fast century type rides. My
regular wheels are Velocity Aerohead/OC with 36 14/15ga butted spokes
laced to Ultegra hubs. As I understand it, one of the main ways aero
rims reduce wind resistance is by having shorter spokes which keeps the
spoke velocity down out at the rim. So will a 30mm deep rim like a
Velocity Deep V offer any real Aero advantages over the 21mm Aeroheads?
Now what about spoke count? How would 28 spokes up front do for a
215lbs rider? Most of the aero advantages are found in the front wheel
(vs back wheel) so I suppose there is no reason not to use 36 in the
back, but will 28 up front reduce resistance noticeably?

So the questions a

Will Deep V's make a diiference?

Is 28 spokes up front dumb for a 215lbs rider?

Will there be any significant aero advantage to 28 over 36 anyway?

My race pace and the speeds where these wheels will be used is around
40km/h.

Thanks,

Joseph

i'm #205 and ride a 24 spoke mavic cosmos front. no problems. with an
even deeper rim like the one you're proposing, 28 will be no issue at all.

in fact, i also ride a 16 spoke shimano r540, no problems.

wrote:
So the questions a

Will Deep V's make a diiference?

Is 28 spokes up front dumb for a 215lbs rider?

Will there be any significant aero advantage to 28 over 36 anyway?

I posted a collection of data here awhile back... unfortunately you
have to register at the site to see it:
http://forums.roadbikereview.com/sho...d.php?t=60465&

Conclusion? Hard to say... but an aero (30mm deep) aluminum rim with
aero spokes seems to be almost as fast as a fancy carbon wheel except
in strong side winds... and costs nearly the same as a conventional
wheel. We are talking about a couple tenths of a mph to be gained over
what you have now...

Zipp did a little research on the effect of spoke count and the
difference was so small that it was in the noise... so I'd say put in
enough spokes. But... if you are using a stiff aero rim (like the Deep
V) then you don't need as many as you have with the Aeroheads. I think
28 in the front would be fine.

Use light butted aero spokes like CX-Rays or Aerolites... or if you
want to save some money, go with Wheelsmith AE15s... they are cheap in
the US at least (under $1 each some places). You might want to put
heavier butted round spokes on the drive rear, though.

There are some pretty nice 30mm Niobium rims that are available from
IRD and Speedcific. They are fairly light at 460g... and I haven't
heard anything bad about them. At your weight you might be better off
with Deep Vs or something similar, though.

Get a good build... that will certainly help.

John Forrest Tomlinson wrote:
On Thu, 07 Dec 2006 03:17:15 GMT, Paul Kopit wrote:

The most significant aero difference can be achieved by the rider's
position on the bicycle. Get yourself more aero before looking at the
equipment.

Can he do both? Is that allowed? Do you know if he hasn't worked
hard on his posiition?

He certainly cannot. One or the other. We can not be to radical in
life.

Andres
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JT
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On Thu, 07 Dec 2006 03:17:15 GMT, Paul Kopit wrote:

The most significant aero difference can be achieved by the rider's
position on the bicycle. Get yourself more aero before looking at the
equipment.

Can he do both? Is that allowed? Do you know if he hasn't worked
hard on his posiition?
--
JT
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On Thu, 07 Dec 2006 03:17:15 GMT, Paul Kopit wrote:

If the roads are in excellent condition and you are speeding along at
40k/hr, you can use a 28 hole rim. When you hit a hole, you re-rim
the hub.

You sound quite certain that with that rider the rim will be damaged.

Is there some break point number of spokes where it won't happen with
such certainty? Like 28 spokes: almost certainly rim damage vs 36
almost certainly no rim damage?

And if so, how did you find this break point?
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JT
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John Forrest Tomlinson wrote:
On Thu, 07 Dec 2006 03:17:15 GMT, Paul Kopit wrote:

If the roads are in excellent condition and you are speeding along at
40k/hr, you can use a 28 hole rim. When you hit a hole, you re-rim
the hub.

You sound quite certain that with that rider the rim will be damaged.

Is there some break point number of spokes where it won't happen with
such certainty? Like 28 spokes: almost certainly rim damage vs 36
almost certainly no rim damage?


I think that there is a bit of an exageration. I've seen plenty of
heavy riders on weekend rides with low spoke count wheels and high
profile rims riding on rough roads weekend after weekend with no rim or
wheel damage. I'm talking about the boutique wheels that come on bikes
nowadays with 20 to 24 spokes. These guys ride wheels without properly
tensioning them, stree relieving them, etc.

I wouldn't say that these sort of wheels will last 20,000 miles. But
Joseph is only looking for att wheel. I would say that a properly built
front wheel with a high profile rim and few spokes would be fine. I
would suggest just getting a very aero front wheel only and forget
about the rear.

Andres

And if so, how did you find this break point?
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John Forrest Tomlinson wrote:
On Thu, 07 Dec 2006 03:17:15 GMT, Paul Kopit wrote:

The most significant aero difference can be achieved by the rider's
position on the bicycle. Get yourself more aero before looking at the
equipment.

Can he do both? Is that allowed? Do you know if he hasn't worked
hard on his posiition?

My position is dictated by comfort. Long rides are where my priorities
are, so that is what sort of position I have favored. Here are pics of
my TT set-up:

http://arbitrary.org/IMG_1963.jpg
http://arbitrary.org/IMG_1965.jpg

Aside from the fact that my helmet seems to add about a square foot to
my frontal area, and I guess my elbows could maybe be closer, I think
it's pretty good. I have broad shoulders, but I scrunch them up in TT
position. My road position has the seat about 1" further back and the
stem flipped to raise the bars about 1". I only ride about 5 TT's per
year, so I don't really care about them that much. I try to be aero on
my long rides, but comfort is key there and I have my comfort dialed in
pretty good, so any improvements will come from equipment I believe.

Joseph

Ron Ruff wrote:
wrote:
So the questions a

Will Deep V's make a diiference?

Is 28 spokes up front dumb for a 215lbs rider?

Will there be any significant aero advantage to 28 over 36 anyway?

I posted a collection of data here awhile back... unfortunately you
have to register at the site to see it:
http://forums.roadbikereview.com/sho...d.php?t=60465&

Conclusion? Hard to say... but an aero (30mm deep) aluminum rim with
aero spokes seems to be almost as fast as a fancy carbon wheel except
in strong side winds... and costs nearly the same as a conventional
wheel. We are talking about a couple tenths of a mph to be gained over
what you have now...

Zipp did a little research on the effect of spoke count and the
difference was so small that it was in the noise... so I'd say put in
enough spokes. But... if you are using a stiff aero rim (like the Deep
V) then you don't need as many as you have with the Aeroheads. I think
28 in the front would be fine.

Use light butted aero spokes like CX-Rays or Aerolites... or if you
want to save some money, go with Wheelsmith AE15s... they are cheap in
the US at least (under $1 each some places). You might want to put
heavier butted round spokes on the drive rear, though.

There are some pretty nice 30mm Niobium rims that are available from
IRD and Speedcific. They are fairly light at 460g... and I haven't
heard anything bad about them. At your weight you might be better off
with Deep Vs or something similar, though.

Get a good build... that will certainly help.

I was thinking CX-Rays and American Classic hubs. I was also planning
on building them myself. That way if they fail I can blame it on my
weak building skills instead of any foolish component specification
choices! Maybe round in the back on both sides?

Joseph

wrote:
Hi All,

I still haven't won lotto yet, so I don't think some Zipp 404's or
similar wheels will be in my x-mas stocking this year, so I am thinking
about lower cost options.

I have some nice everyday wheels, so I am looking into "race" wheels to
be used in club races, club TT's, and fast century type rides. My
regular wheels are Velocity Aerohead/OC with 36 14/15ga butted spokes
laced to Ultegra hubs. As I understand it, one of the main ways aero
rims reduce wind resistance is by having shorter spokes which keeps the
spoke velocity down out at the rim. So will a 30mm deep rim like a
Velocity Deep V offer any real Aero advantages over the 21mm Aeroheads?
Now what about spoke count? How would 28 spokes up front do for a
215lbs rider? Most of the aero advantages are found in the front wheel
(vs back wheel) so I suppose there is no reason not to use 36 in the
back, but will 28 up front reduce resistance noticeably?

So the questions a

Will Deep V's make a diiference?

'Maybe' teeny difference at higher speeds.

Is 28 spokes up front dumb for a 215lbs rider?

Not dumb if the rim is not light also.

Will there be any significant aero advantage to 28 over 36 anyway?

NOT significant.

My race pace and the speeds where these wheels will be used is around
40km/h.

Thanks,

Joseph

There are other ways to get faster and they all involve things other
than equipment, like bike fit and position, fitness, training, being as
light as you can and also be healthy...WAY too much emphasis on the
bike, not nearly enough on the rider.

John Forrest Tomlinson wrote:
On Thu, 07 Dec 2006 03:17:15 GMT, Paul Kopit wrote:

The most significant aero difference can be achieved by the rider's
position on the bicycle. Get yourself more aero before looking at the
equipment.

Can he do both? Is that allowed? Do you know if he hasn't worked
hard on his posiition?
--
JT
****************************
Remove "remove" to reply
Visit http://www.jt10000.com
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I think Paul's point was mine also. Certainly equipment changes are
allowed but the performance differences are minor, teeny when compared
to position changes.