Bernie Sluzalek said:I have recently observed an MA3 rim crack at a few eyelets in a
machine built wheel that came with a bike (I didn't choose or build
that wheel, I just hand finished it). Of course, this will surprise
nobody - I'm going to replace the spokes with 1.7/2.0mm ones (both
sides) and use a different rim when I replace this wheel because of
the following.
Quoted message said:On dismantling the wheel I was reminded of how it had been built
with 2.0/2.3mm on the right and 2.0mm plain on the left - I am right
in believing thicker less-stretchy spokes are associated with
cracked eyelets in poor-quality rims more so than thinner ones?
The MA-3 is a miserable attempt at cutting manufacturing cost by not
using eyelets and sockets. It was a miserable failure from the start
and I don't believe you will find it in their lineup of rims anymore:
http://www.mavic.com/ewb_pages/r/route.php
A rim that is so close to failure with thick spokes is not a safe bet
with thinner spokes although thin spokes are better for any wheel with
a reasonable spoke complement. The reason for thick spokes is
generally for ease of build because they don't twist when approaching
final tension. It is not because they are stronger in most instances.
This is doubly true for straight gauge spokes.
Quoted message said:Having seen this happen here, I am now worried about the touring
wheels that I have built for this coming summer with which I intend
to carry heavy loads. The rims are stocky Rigida Sputniks that are
unfortunately anodised - in this I didn't have a choice since
non-anodised rims were unavailable. They are socketed/double
eyeleted though, unlike MA3.
That ought to work. I think the manufacturers slowly got the message
that hard anodizing was a failure and cause failures, so most of the
current anodizing is thin enough to not cause problems.
Quoted message said:The rear has very beefy plain gauge 2.3mm on the drive side (they go
to 2.0mm at the threaded end, but they are effectively plain gauge)
and 2.0/1.7mm on the left. And they're tight, of course.
That's not a good combination. Make sure you take along spare spokes,
just in case you get enough miles to get a failure on the road.
Quoted message said:Is this wheel doomed to the dreaded cracking problem?
Who came up with 2.3mm spokes? I can't believe that wheel builders
asked for this but for what other reason would manufacturers offer
them. Consider that one set of 1.8-1.6mm diameter spokes have been
serving me well for more than 300,000 miles (with several rim
replacements for brake wear).
Quoted message said:This is the first time I've built a touring wheel and it's also my
first wheel with thicker spokes on the right - normally I build
wheels with 1.7/2.0mm and they last till the rim wears down at the
braking surface (I've never actually broken a spoke in one of my own
wheels so far).
So why did you choose these spokes?
Quoted message said:Would it be wise to replace the 2.3mm spokes with 2.3/2.0mm, 2.0mm
plain gauge or even 1.7/2.0m? Or am I justified in using 2.3mm?
Remember, I'll be carrying very heavy camping equipment etc.
I don't know what sort of hubs you have but the ones I am using had
flange holes just large enough to pass the threads of a 1.8mm diameter
spoke. Your flanges must have gaping holes to accept such large
spokes in the first place which is not a good start at the hub.
Quoted message said:I'd be very grateful if someone practically experienced with this
*in the real world* could advise me.
I find this difficult because I don't know what sort of hubs are made
with reasonable spoke holes and could not find a rim that I would like
to use at the last InterBike trade show. Fortunately, good spokes are
still available.
Jobst Brandt