Broken spokes...again

You need a new rim. By the time you have the wheel rebuilt, a new wheel
may be the same price.

AcctHitman said:

A couple of weeks ago, my LBS replaced a broken spoke on my rear
wheel. After three rides, the wheel was way out of true. After I had
the wheel retrued, I broke two spokes on my next ride.

A friend suggested that the problem is the mix of new spokes and
seven-year-old spokes in the wheel. Does the wheel need to be
respoked or is the LBS just doing a bad job of trueing the wheel?

The wheel is on my MTB (used for pavement only). The spokes are
stainless steel, 14 gauge. The wheel has about 4700 miles of use over
seven years. I weight about 155 pounds.

Thanks

Sad but true. You need all new spokes, and it might be easier/cheaper to
replace the rim. And it's the rear wheel that gets stressed...

-- M. Powell

"Mike Schwab" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

You need a new rim. By the time you have the wheel rebuilt, a new wheel

((SNIP))

"AcctHitman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

A couple of weeks ago, my LBS replaced a broken spoke on my rear
wheel. After three rides, the wheel was way out of true. After I had
the wheel retrued, I broke two spokes on my next ride.

A friend suggested that the problem is the mix of new spokes and
seven-year-old spokes in the wheel. Does the wheel need to be
respoked or is the LBS just doing a bad job of trueing the wheel?

The wheel is on my MTB (used for pavement only). The spokes are
stainless steel, 14 gauge. The wheel has about 4700 miles of use over
seven years. I weight about 155 pounds.

Sometimes spokes fail because they were nicked by the chain falling off the
cassette/freewheel, that's why many bikes have a protective disk there.
These failures often occur many miles after they were damaged. Other than
that, the most common failure mode is simple metal fatigue. Spokes fatigue
usually because they weren't "stress relieved" when the wheel was
originally built (a one-time operation). If you're interested, the details
of the theory are in the FAQ: http://draco.acs.uci.edu/rbfaq/FAQ/8c.1.html

It's possible that your wheel & spokes could be salvaged by being
stress-relieved and tensioned now, but it's possible that you will still
get broken spokes down the road given the fatigue that has already
occurred. Unfortunately, completely rebuilding that wheel with new spokes
is probably an economic loser, especially since new MTB wheels are pretty
cheap. Not too many bike shops know how to set up new wheels, so if you buy
one from an unenlightened shop your spoke problems may not be over. If
you're inclined, it makes a lot of sense to learn to stress-relieve,
tension, and true a wheel yourself, it's not very difficult.

On 12 Oct 2004 20:55:27 -0700, [email hidden] (AcctHitman)

Quoted message said:

A couple of weeks ago, my LBS replaced a broken spoke on my rear
wheel. After three rides, the wheel was way out of true. After I had
the wheel retrued, I broke two spokes on my next ride.

A friend suggested that the problem is the mix of new spokes and
seven-year-old spokes in the wheel. Does the wheel need to be
respoked or is the LBS just doing a bad job of trueing the wheel?

The wheel is on my MTB (used for pavement only). The spokes are
stainless steel, 14 gauge. The wheel has about 4700 miles of use over
seven years. I weight about 155 pounds.

The LBS is clearly doing a bad job, the problems are almost certainly
not caused by mixing old and new spokes. I have a rear wheel that
suffered chain suck which cut into all eight outboard spokes while I
was on a solo ride way out in the country. I thought I was in serious
trouble, but having nothing to lose I freed up the chain and kept
riding. I finished the rest of the ride without incident and decided
to just keep riding on that wheel until a spoke broke. None ever did.

Years later I decided the rim needed replacing (the brake surfaces
were too worn for my taste), so I rebuilt the wheel. I just replaced
the eight cut spokes. I had to close the cuts with a ViseGrip in order
to get them to pass through the hub's spoke holes. That was about five
years ago. Since re-rimming I haven't had to touch the wheel with a
spoke wrench.

Lessons learned: 1) Spokes don't break because they get cuts or
notches in them. Spokes almost always break at their ends, where the
stresses are highest. 2) Mixing old and new spokes doesn't inherently
cause problems. As Jobst has pointed out here many times, old spokes
have proven their mettle by their very age.

Unless your rim has been severely taco'ed the symptoms you've
described indicate an under-tensioned and perhaps un-stress-relieved
wheel.

jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

"John Everett" <[email hidden]> wrote

Quoted message said:

Lessons learned: 1) Spokes don't break because they get cuts or
notches in them.

You were lucky, often spokes do break at notches. Perhaps "often" is too
strong a word, I have had many that have lasted, but several that have let
go -- many miles later.

Actually, I had a rim that kept breaking spokes. Had them replace all
spokes and nipples. Still breaking spokes. New rim and no more broken
spokes. Cause was the rim was warped, and when they trued it with the
new spokes there were several at maximum temsion just to get the rim
straight.

M Powell said:

Sad but true. You need all new spokes, and it might be easier/cheaper to
replace the rim. And it's the rear wheel that gets stressed...

-- M. Powell

"Mike Schwab" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

You need a new rim. By the time you have the wheel rebuilt, a new wheel

((SNIP))

Mike Schwab said:

Actually, I had a rim that kept breaking spokes. Had them replace all
spokes and nipples. Still breaking spokes. New rim and no more broken
spokes. Cause was the rim was warped, and when they trued it with the new
spokes there were several at maximum temsion just to get the rim straight.

Keep in mind that this is something that should have been checked as they
were replacing the spokes. I would not consider this a reasonable action
by the shop. If the rim was that bad, it would have been obvious when
they unlaced it.

--

David L. Johnson

__o | Do not worry about your difficulties in mathematics, I can
_`\(,_ | assure you that mine are all greater. -- A. Einstein
(_)/ (_) |