Mavic open sport clincher rims

someone writes anonymously:

Anyone have experience with or knowledge of these? Could they be
the second coming of the MA2, or something close (he says
optimistically)?

It looks like the MA3 with a new name. The MA3 is a cheap, bad rim,
which is prone to cracking around the eyelets with common spoke
tensions. Even Mavic admits this by specifying a lower rider weight
limit for the MA3 than for example Open Pro. The Open Pro is a much
better choice.

What does rider weight have to do with eyelets cracking? Eyelets
failure is a function of spoke tension not rider weight. Are you
suggesting the Mavic spec lower spoke tension for the MA3?

The cracks are fatigue failures that develop from load cycles. Spoke
load is at its maximum in the unloaded wheel and drops closer to zero
the greater the wheel load becomes. Therefore, load is a major effect
in fatigue life.

Rim sockets distribute spoke loads to a 0.5" diameter on the inner
wall of the rim and a 3/8" diameter on the outer wall. For this
reason socketed rims seldom suffer cracks and high spoke tension is
not a fatigue failure consideration. In the days when all good rims
had sockets and eyelets, tension was limited primarily by compression
buckling (spontaneous pretzel) of the rim that defined the tension
limit. I have not seen any rims made today that work at that level
and that is why we need thread glue to keep spoke nipples from
unscrewing because they cannot be made tight enough to not become
slack without cracking rims.

Jobst Brandt

In article ,
wrote:

someone writes anonymously:

Anyone have experience with or knowledge of these? Could they be
the second coming of the MA2, or something close (he says
optimistically)?

It looks like the MA3 with a new name. The MA3 is a cheap, bad rim,
which is prone to cracking around the eyelets with common spoke
tensions. Even Mavic admits this by specifying a lower rider weight
limit for the MA3 than for example Open Pro. The Open Pro is a much
better choice.

What does rider weight have to do with eyelets cracking? Eyelets
failure is a function of spoke tension not rider weight. Are you
suggesting the Mavic spec lower spoke tension for the MA3?

The cracks are fatigue failures that develop from load cycles. Spoke
load is at its maximum in the unloaded wheel and drops closer to zero
the greater the wheel load becomes. Therefore, load is a major effect
in fatigue life.

Rim sockets distribute spoke loads to a 0.5" diameter on the inner
wall of the rim and a 3/8" diameter on the outer wall. For this
reason socketed rims seldom suffer cracks and high spoke tension is
not a fatigue failure consideration. In the days when all good rims
had sockets and eyelets, tension was limited primarily by compression
buckling (spontaneous pretzel) of the rim that defined the tension
limit. I have not seen any rims made today that work at that level
and that is why we need thread glue to keep spoke nipples from
unscrewing because they cannot be made tight enough to not become
slack without cracking rims.

Sun CR-18. I tensioned one until it became a circle on a
surface of negative curvature. I reduced the tension to
bring it flat, and raised the tension to the maximum, then
trued, balanced, and stress-relieved. Two years later it
and its brother are true with no cracking. $20 US.
Eyelets, but no sockets.

--
Michael Press

Michael Press wrote:

Sun CR-18. I tensioned one until it became a circle on a
surface of negative curvature. I reduced the tension to
bring it flat, and raised the tension to the maximum, then
trued, balanced, and stress-relieved. Two years later it
and its brother are true with no cracking. $20 US.
Eyelets, but no sockets.

Sun rims are made of _much_ more ductile material than Mavic rims.
Based on my experience with them, I would expect them to pucker at the
eyelets at a lower spoke tension than what would cause them to crack
there.

I find Sun rims to be much more reliable than recent Mavic rims. That
said, the CR18 is a significantly heavier rim than the MA3, Open Pro,
etc., and should be expected to display superior reliability on that
basis.

Chalo Colina

I retract my previous comment, upon finding that the claimed weight of
the Sun CR18 is actually 20g less than that of the Mavic Open Sport.
This discovery compounds my disappointment with Mavic's recent
products. Hopefully the market will wise up soon enough; hype can only
carry you so far if there is no substance to back it up.

Chalo

wrote:

What does rider weight have to do with eyelets cracking? Eyelets failure is
a function of spoke tension not rider weight.

Yes, but heavier riders need higher spoke tensions for the wheel to be
reliable, if everything else is equal.

Are you suggesting the Mavic spec lower spoke tension for the MA3?

It was reported here that the specified rider weight limit is lower for
MA3, unless my memory fails. Perhaps by Peter Chisholm?

-as

Zog The Undeniable wrote:
Peter Cole wrote:

Since it's not a significant proportion of the ~0.5mm service wear
depth, it won't be a significant factor for the lifetime of the rim.
Kind of like a car feature that stops working after 5K miles -- IOW, a
scam.


The original idea of machined sidewalls was to clean off the anodising,
which plays havoc with wet braking. In the old days WTB actually sold
abrasive pads to grind that expensive anodising off the brake tracks,
after which you could switch to normal pads.

So machined rims offer better braking than completely anodised rims, but
not better than a plain alu rim. The rim manufacturers created a
problem then invented something else to fix it. The consumer gets the
bill for both.

I think you're right about that. I bought a pair of dark anodized Open
Pros (w/o machined brake track) that grabbed/chattered terribly until
the anodizing wore off (something that took a long time).

jim beam wrote:

Chalo wrote:

Open Sports are heavier.

than ma2's?

Claimed weight 490g.

So are most deep rims if I'm not mistaken.

open pros are 420g. that's a good deal less shallow than a 460g ma2.

Still not a deep rim. I'd be surprised if it were more durable or more
resistant to any kind of damage than its predecessor.

the flat wall of a new machines rim mates completely with the flat
profile of a new pad. 100% braking, day 1. a curved rim, ma2, + new
flat brake pad makes 50% contact day 1. your call on which is safer.

I think you've illustrated which one has more contact area on day 1.
In any case, frictional force is not proportional to surface contact
area, but to load and frictional coefficient. Kool Stop Continentals
(with a small area) work the same as Kool Stop Mountain pads (with a
large area) on the same brake. And just as you imply, after a few
miles they're all 100% conformal.

8. welded joints offer better mechanical strength

Not for Mavics, they don't.

sorry, but welded joints are nearly as strong at the parent material.
that's /not/ the case with a pinned joint.

Try to tension new welded Mavics up enough
to carry a good load, and they will bulge at the weld before they start
to squish at the valve hole.

dude, if you're tensioning a rim that high, you're insane and have *NO*
right to complain about equipment failure.

I haven't squished a valve hole in a long time. Most of the time, I
did so when I was tying to true up a tired rim without making any of
the spokes too loose.

When I squished a welded joint on a Mavic rim recently, it was at a
tension that wasn't high enough to keep the left side rear spokes from
loosening-- a lower tension than what I have on some of my other 700c
rims of equal or ligher weight without problems.

The fact that the rim pooched out at the welded joint, rather than at
the valve hole where the cross section is considerably less, is
conclusive proof that you are wrong about the welded joint being
"nearly as strong as the parent material". The _annealed_ version of
the parent material, maybe, but that's a completely different thing.

But it's clear to me that the MA2 was not
seriously flawed in in any particular way,

for those of us that have lived outside of palo alto, you know, where it
might rain occasionally, sockets that rust are a big problem. rims that
flat spot are a problem.

The MA2s I built for my sweetie see use in all kinds of weather here in
Seattle. No rust yet, but maybe one day; you never know.

open pros are a great rim. light, strong, doesn't
crack, doesn't rust, lasts. available in silver anodized, black
anodized, cd anodized & ceramic. no reliability problems as far as i know.

I'll have to take your word for it. Their reputation among cycle
messengers here is not stellar, but a lot of them use tham anyway. The
T519 and A719 rims I have tried recently have been utter junk-- heavy
touring/commuting rims that couldn't withstand heavy touring/commuting
conditions.

Chalo

Yes I agree. Heavier riders need more spoke tension, or more spokes than
lighter riders, all else being equal. So as Jobst stated the rim may be too
weak for the spoke tension required to maintain a true wheel without
fatiguing. If you laced with a lower tension the eyelets would not crack;
however the rims would not stay true. If this is the case with the ma3, then
they are not suitable for all but the lightest riders and there are better
choices.

cel


"Antti Salonen" wrote in message
...
wrote:

What does rider weight have to do with eyelets cracking? Eyelets failure
is
a function of spoke tension not rider weight.

Yes, but heavier riders need higher spoke tensions for the wheel to be
reliable, if everything else is equal.

Are you suggesting the Mavic spec lower spoke tension for the MA3?

It was reported here that the specified rider weight limit is lower for
MA3, unless my memory fails. Perhaps by Peter Chisholm?

-as

Chalo wrote:
Mark Hickey wrote:
"Chalo" wrote:

Besides, aren't you the guy who says spoke gauge has an effect on ride
quality? If you can feel that, then I don't know why you wouldn't
prefer shallow rims since they have a much more pronounced effect on
radial deflection. (Not that I can feel any.)

It seems to me that if Chalo
can't feel vertical deflection on his rims / spokes / frame - the rest
of us don't stand a chance of doing so. He's going to get (at least)
2.5x as much deflection out of his equipment as I can (and a LOT more
than all but the very biggest of us).

You know, it could just be that I'm grossly insensitive.

Chalo rides much larger tyres than the rest of us, too. If the rest of
the bike is as stiff as my bike, but Chalo has larger and softer tyres,
I think he'd be *less* prone to sense any changes in the bike.

--
Dave
dvt at psu dot edu

dvt wrote:


Chalo rides much larger tyres than the rest of us, too. If the rest of
the bike is as stiff as my bike, but Chalo has larger and softer tyres,
I think he'd be *less* prone to sense any changes in the bike.

That's an interesting notion, and I'm sure it it may be relevant for
tires like my favorite 700x60 Schwalbe Big Apples, which I run at a
modest 50psi or so. However, it's a fact that a fatter tire is
"harder" (that is, it displays less vertical travel on a given bump)
than a skinny tire at the same pressure. So my 700x32 tires at 105psi
give a harder ride than 700x23 tires at the same pressure.

In the basis of footprint size, my Big Apples should be yielding a
harder ride than skinny road bike tires too, but they don't seem to do
that in practice. I suspect that it has to do with the rim's
deflection into the tire casing rather than the tire's deflection at
its contact patch.

Chalo Colina