MA3 rim failure, where to now

MA3 have a good record as far as I know.
I would get a new wheel builder.
B

(remove clothes to reply)

George MacKenzie writes:

Would building the non drive side radially help, on the same theory
I noted that the Tiagra hubs have a large diameter waist, would
skinnier hubs like the 105 transfer less torsion and thus let me
get away with less tension.

Sheldon "wheels" Brown has a lot of good things to say about half
radial rear wheels. Check out his wheel building web pages. I've
never had a 3x36 rear break anything other than a pulling drive side
spoke, and I've never built a half radial rear but for what it's
worth, after reading Sheldon's page, and hearing your problem, I'd
give it a shot.

You lose more than you gain with radial spokes because the
interleaving of spokes helps keep them tight enough that they can't
unscrew under shock loads. Radial may change the lateral angle a wee
bit, but it is minuscule and doesn't make up for the non-interleaving.

Jobst Brandt

Since left spokes experience less tension than right, they fare better when
gauged smaller. Ex: 14-15dbright/15-16dbleft.
The thicker spokes stretch 1-2 mm@150kg and the thin ones
a similar amount @ the 80kg they are likely to be installed at.
It is this static stretch that protects against the fatigue from
de-tensioning above the contact patch in normal use.
Tom

--
Bruni Bicycles
"Where art meets science"
brunibicycles.com
410.426.3420
AndyMorris wrote in message
...
Last year I started cycling again after 10 years, I had previously made my
living from the cycle trade and had built wheels for many satisfied
customers.

I decided to build my own wheels and selected Shimano Tiagra hubs, mavic
MA3's and sapin db (2.0/1.8) spokes 36 hole 3 cross.

I built the wheels according to the book, all went well although I was a
bit
worried how things would hold up due to the extra dish, for the 9 speed
freehub and my extra mass after the 10 years off the bike.

After a while I started getting loose (pushing) spokes on the non drive
side, so I upped the tension and stress relived again.

After a bit longer a couple of spokes on the non drive side (pushing)
broke
in a couple of weeks so I rebuilt the non drive side after taking off the
tension, and being carefull to lube the eyelets and threads.

I built it with more tension this time, not enough to taco it, but enough
that the drive side felt very tight and stressed relieved it very hard.

After about 500 miles, I've had 2 more non drive side spokes go, this time
pulling ones, when I replaced the second one tonight, I noticed that the
rim
had two parallel 'cracks' around one of the eyelets. The eyelet have move
around 1mm in where it should with a crack each side running round the rim
for around 5mm each way.

_______________________
___
O O
---
-----------------------

At no time did I put enough tension in to get near tacoing the wheel, I
still have the 'feel' for that, neither was I near damaging nipples with
my
old red spokey, however the drive side spokes were tighter than I remember
spokes being from my days of doing it for a living, that was what made me
stop adding tension.

I'm stuffed, if I put enough tension the rim will crack up before it
becomes
unstable, if I leave it with less tense the spokes fail.

I weigh 16 stone (nearer 18 last year when I restarted cycling), have no
interest in off road use 25mm tyres, commute 10 miles a day and try to get
out for a couple of hours at the weekends.

Would Open 4's be better? They are lighter, but probably have greater
stiffness (4th moment or what ever it is) and have double eyelets.

Would building the non drive side radially help, on the same theory I
noted
that the Tiagra hubs have a large diameter waist, would skinnier hubs like
the 105 transfer less torsion and thus let me get away with less tension.

Does anyone in the UK sell the very nice looking Torelli Master Rims ?

Is it worth going for an OCR rim? Are there any that are 36h and double
eyeleted?

I don't want a big wide heavy touring rim, I'm sure if I could get a good
old MA2 I could build myself a wheel that would last for me.

Does anyone know where Mr Brandt lives so we can rob him? Or if he has any
vices we can bribe or corrupt him with?


--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK


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Andy- After about 500 miles, I've had 2 more non drive side spokes go, this
time
pulling ones, when I replaced the second one tonight, I noticed that the rim
had two parallel 'cracks' around one of the eyelets. The eyelet have move
around 1mm in where it should with a crack each side running round the rim
for around 5mm each way. BRBR

We have seen a few MA-3 do this as well.

Andy- Would Open 4's be better? They are lighter, but probably have greater
stiffness (4th moment or what ever it is) and have double eyelets. BRBR

I recommend a CXP-33 or Velocity Fusion. Radial lacving won't do anything for
you. I suspect the left side spokes got loose initially because the right side
tension wasn't high enough, then you raised it above where it ought to be. Or
the rim is deformed somehow making for a section of erratic(low) tension.


Andy Does anyone in the UK sell the very nice looking Torelli Master Rims ?
BRBR

I can send these to you as well as Fusions-


Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Or
the rim is deformed somehow making for a section of erratic(low) tension.

That's the first thing I would check. Unlace your rim and see if the damn thing can even
lay flat. Then check the circumference at several places to see if it's round , too. No
sense in wasting time on a taco'd rim. All the spokes do not need to have the exact same
tension but they should not be too far off, either. Of course, it could be nothing with
the wheel and everything with your riding style and terrain. Just a thought.

This sounds like a fun problem but it's hard to diagnose over the Internet.

Dave

P.S. If you do have a taco'd rim then swap it out with your front rim (assuming it is
fine). I've done this and was able to get several thousand more miles out of my wheels.

writes:

You lose more than you gain with radial spokes because the
interleaving of spokes helps keep them tight enough that they can't
unscrew under shock loads. Radial may change the lateral angle a wee
bit, but it is minuscule and doesn't make up for the non-interleaving.

Do you have a suggestion for the big guy who breaks 3x36 wheels?

Thanks to everyone who replied.


Qui si parla Campagnolo wrote:

I suspect the left side spokes got loose initially
because the right side tension wasn't high enough, then you raised it
above where it ought to be.

I suspect your right, the wheels wasn't quite tight enough. I wasn't used to
modern 9 speed wheels. Also the customer (me) is a fairly chunky bloke who
lives in a hilly area, uses low gears and tend to pedal triangles rather
than circles.

The extra tension I put in that slowed the rate of spoke breakage and
knackered the rims was only about 1 turn all round.

Or the rim is deformed somehow making for
a section of erratic(low) tension.


I haven't taken the rim off yet, but it doesn't 'feel' that the rim has
suffered major deformation from hitting anything. The tension is even and
the wheel is true to within 'doing it in the frame' limits, say 0.5mm.

I did once hit something small that punctured thru the tyre and both sides
of the tube. It happened to be right on the join and left a small (0.5mm)
'flairing' on one rim wall on one side of the join. This was fixed with a
little tap of a hammer to bring it in line with the other side of the join.
The eyelet that pulled away was nowhere near this.

QSP Campag sugested

I recommend a CXP-33 or Velocity Fusion

I can't get on mavics site at the moment or find anything more about
Velocity. Do they have double eyelets? This would seam to be a crucial
factor in being able to get enough tension in box section rims on deeply
dished wheels.

The 1/2 radial debate carries on, I can see both sides of that argument, but
I'm not sure Jobst is addressing Sheldons main point about torsion not
detensioning the non gear side spokes. On the other hand I think I'm more
likely to detension them from the side loads when honking so radial is going
to do nothing about that..

jim beam wrote:

and get a tensiometer. park make one that sells for about
$50.


I'd feel like getting one if mavic or anyone published figures for both the
maximum tension per single spoke (for eyelet failure) and the max total loan
for taco failure.

Taco failure you can feel coming on and drop a bit of tension. Surely eyelet
failure is a result of crap design (single eyelets?) and materials and a
damn good reason to join


Tom from Bruni wrote:
Since left spokes experience less tension than right, they fare
better when gauged smaller. Ex: 14-15dbright/15-16dbleft.
The thicker spokes stretch 1-2 mm@150kg and the thin ones
a similar amount @ the 80kg they are likely to be installed at.
It is this static stretch that protects against the fatigue from
de-tensioning above the contact patch in normal use.


This I can see some sense in. The sapim laser 2mm/1.5mm look tasty on that
basis.

I will propbably have to get another MA3's from my long suffering LBS and
rebuild on the same spokes to keep me going for the next few weeks.

I will then see how much its going to cost me to get a pair of Torelli
Masters shipped over and decide if that's too much and instead get some open
pro's. I'll try and get my LBS to get some Sapim Laser spokes in. I'll read
the book again, get some really thick gloves and see how I do.

Again many thanks

--
Andy Morris

AndyAtJinkasDotFreeserve.Co.UK


Love this:
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On Sun, 7 Sep 2003 01:39:14 +0100, "AndyMorris"
wrote:

Last year I started cycling again after 10 years, I had previously made my
living from the cycle trade and had built wheels for many satisfied
customers.

I decided to build my own wheels and selected Shimano Tiagra hubs, mavic
MA3's and sapin db (2.0/1.8) spokes 36 hole 3 cross.

I built the wheels according to the book, all went well although I was a bit
worried how things would hold up due to the extra dish, for the 9 speed
freehub and my extra mass after the 10 years off the bike.

After a while I started getting loose (pushing) spokes on the non drive
side, so I upped the tension and stress relived again.

After a bit longer a couple of spokes on the non drive side (pushing) broke
in a couple of weeks so I rebuilt the non drive side after taking off the
tension, and being carefull to lube the eyelets and threads.

I built it with more tension this time, not enough to taco it, but enough
that the drive side felt very tight and stressed relieved it very hard.

After about 500 miles, I've had 2 more non drive side spokes go, this time
pulling ones, when I replaced the second one tonight, I noticed that the rim
had two parallel 'cracks' around one of the eyelets. The eyelet have move
around 1mm in where it should with a crack each side running round the rim
for around 5mm each way.


You might consider a Velocity Aerohead rim with offset spoke
drillings. These rims have no eyelets but seem to work well.

For what it's worth, I have a pair of wheels with anodized MA-3 rims,
db 2.0/1.8 DT spokes, and XT hubs. I weigh about the same as the OP,
but have over 3x the miles on the above with no problem. Spoke
tensions for the rear wheel are 80 Kgf on the left and 130 on the
right (from memory.) Perhaps I'm just lucky.

Steve Shapiro

"Simon Brooke" wrote in message
. uk...

But against that a three cross wheel is substantially springier than a
radial.

I'd like to see some backup for this, please.

Assuming you mean what is commonly meant by "springier" and
"substantially" - i.e deflection per unit force and a difference of, say,
10%.

Numbers please.

George- Do you have a suggestion for the big guy who breaks 3x36 wheels?
BRBR

CVP-33, Mavic T520, Velocity Deep V...14/15 3 cross brass nipps, built well, of
course...

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"