broken spokes, cassette/drive train compatability

Hello,

The spokes on my rear wheel keep breaking (three so far in
two weeks). Every time I replaced a spoke, the truing was
OK, but it just did not stop spokes from breaking. Could
there be something wrong that I did not see?

The current drive train is seven-speed. I was thinking of
putting in place a wheel with a six-speed cassette. I
suppose there will be fewer broken spokes. Will the six-
speed cassette work with the seven-speed chain and rear
derailleur?

Thanks.

Lisp949 wrote:
Hello,

The spokes on my rear wheel keep breaking (three so far in
two weeks). Every time I replaced a spoke, the truing was
OK, but it just did not stop spokes from breaking. Could
there be something wrong that I did not see?

The current drive train is seven-speed. I was thinking of
putting in place a wheel with a six-speed cassette. I
suppose there will be fewer broken spokes. Will the six-
speed cassette work with the seven-speed chain and rear
derailleur?

Thanks.

what brand are the spokes?

In article .com,
Lisp949 wrote:
The spokes on my rear wheel keep breaking (three so far in
two weeks). Every time I replaced a spoke, the truing was
OK, but it just did not stop spokes from breaking. Could
there be something wrong that I did not see?

Make sure you check your spoke tension as well as trueness.

anonymous writes:

The spokes on my rear wheel keep breaking (three so far in two
weeks). Every time I replaced a spoke, the truing was OK, but it
just did not stop spokes from breaking. Could there be something
wrong that I did not see?

Are they high quality spokes... like DT or Sapim stainless? If so,
then I suppose they were not stress relieved after tensioning. Spokes
that are in the act of being deformed at the elbow and threads, are at
yield stress at which fatigue life is short. Tensioning only
guarantees that they remain at yield stress.

Your bicycle shop ought to have "the Bicycle Wheel" in their shop or
on the book shelf. How to stress relieve is described in that book.
Do it!

The current drive train is seven-speed. I was thinking of putting
in place a wheel with a six-speed cassette. I suppose there will be
fewer broken spokes. Will the six- speed cassette work with the
seven-speed chain and rear derailleur?

It will work all except that the inner limit stop screw may not be
effective in preventing the derailleur from over shooting the largest
sprocket. This can drop the chain into the spokes. That's been my
experience with an 8-speed derailleur on 6_speed clusters.

Thanks.

Yrwlcme!

Jobst Brandt

Lisp949 wrote:
Hello,

The spokes on my rear wheel keep breaking (three so far in
two weeks). Every time I replaced a spoke, the truing was
OK, but it just did not stop spokes from breaking. Could
there be something wrong that I did not see?


It could be that the spokes were not properly tensioned to begin with
and are now fatigued at the bends. If so, you will continue to break
spokes until you've replaced them all. It is probably more fruitful to
rebuild the entire wheel with new spokes, but it may simply be cheaper
to replace the whole wheel, assuming the new wheel is properly built
and tensioned. Many (most) machine-built wheels are not properly
tensioned straight out of the box.


The current drive train is seven-speed. I was thinking of
putting in place a wheel with a six-speed cassette. I
suppose there will be fewer broken spokes. Will the six-
speed cassette work with the seven-speed chain and rear
derailleur?

Thanks.

Moving from a 7-speed to a 6-speed cluster gains you nothing. 6-speed
cassettes have more space between the cogs than 7-speed, so the overall
width of the cassette is the same. The amount of dish is the same, so
the wheel won't be any stronger.

(Unless, of course, you went with a conventional hub and a Suntour
Ultra-6 freewheel, but that's a subject best left to finicky gearheads
like me.)

The indefatiguable Sheldon Brown has many articles about this subject:
http://sheldonbrown.com/speeds , among others.

Jeff
Jeff

wrote:
Your bicycle shop ought to have "the Bicycle Wheel" in their shop or
on the book shelf. How to stress relieve is described in that book.
Do it!

Jobst! You never pass up a chance to plug your book or post old
pictures of you at the top of some huge hill in the Alps. I bought the
book years ago before I knew you posted here. If I would have known how
grouchy you get sometimes I would have thought twice about buying the
book.

Seriously though, it's a good book. I bought both Jobst's book and Gerd
Schraner's book and have built many a successful wheelset. Good advice
in both books. I've never seen it in a bike shop though. Amazon has it
sometimes:

http://www.amazon.com/gp/product/096...oks&v=glanc e

-Nate

Dans le message de
oups.com,
JeffWills a réfléchi, et puis a déclaré :
Many (most) machine-built wheels are not properly
tensioned straight out of the box.

I would really like it if you would identify the /many/ and the /most/. I
am amazed that companies which dedicate full production lines, with trained
and supervised technicians, are unable to perform this simple task. Also,
please tell us how untrained, inexperienced, unsupervised and untested
individuals, having only a book in front of them, can do a better job.

Really, I would like to know. I bet Campagnolo, Mavic, Fulcrum,
Lightweight, MODE, and a bunch of other manufacturers would like to know.
Can you please be nice and specific ? Thanks.
--
Bonne route !

Sandy
Verneuil-sur-Seine FR

On Sat, 5 Nov 2005 12:51:49 +0100, "Sandy" wrote:

I would really like it if you would identify the /many/ and the /most/. I
am amazed that companies which dedicate full production lines, with trained
and supervised technicians, are unable to perform this simple task. Also,

That's mostly because the people operating the machines are intern monkeys
instead of highly trained professionals, the machines mostly can't do
proper tensioning, and there is no touch-up truing after the machine
phase.

Also, there is no incentive for manufacturers to do it right, since even a
badly undertensioned wheel will usually last out the warranty period and
doing it right ups costs by a large factor.


Jasper

On Sat, 05 Nov 2005 12:51:49 +0100, Sandy wrote:

Dans le message de
oups.com,
JeffWills a réfléchi, et puis a déclaré :
Many (most) machine-built wheels are not properly
tensioned straight out of the box.

I would really like it if you would identify the /many/ and the /most/. I
am amazed that companies which dedicate full production lines, with trained
and supervised technicians, are unable to perform this simple task. Also,
please tell us how untrained, inexperienced, unsupervised and untested
individuals, having only a book in front of them, can do a better job.

For the first question, even "dedicated" production lines are geared to
speedy production rather than careful wheel-building. "Trained
technicians"? What good wheel-building takes is a little time, and
reasonable technique.

A machine-built standard wheel will be true at first, but the spokes are
far too loose, and are not stress-relieved, and so will fail quickly.
This is not prejudice, but observation.

As for which ones do better, one would hope that the fancy "boutique"
wheels costing over $1000 per pair would do better. For me, though, that
is an untestable hypothesis, since I can build my own wheels for a small
fraction of the price, and they last a very long time.

--

David L. Johnson

__o | And though I have the gift of prophecy, and understand all
_`\(,_ | mysteries, and all knowledge; and though I have all faith, so
(_)/ (_) | that I could remove mountains, and have not charity, I am
nothing. [1 Corinth. 13:2]

David L. Johnson wrote:
On Sat, 05 Nov 2005 12:51:49 +0100, Sandy wrote:


Dans le message de
groups.com,
JeffWills a réfléchi, et puis a déclaré :

Many (most) machine-built wheels are not properly
tensioned straight out of the box.


I would really like it if you would identify the /many/ and the /most/. I
am amazed that companies which dedicate full production lines, with trained
and supervised technicians, are unable to perform this simple task. Also,
please tell us how untrained, inexperienced, unsupervised and untested
individuals, having only a book in front of them, can do a better job.


For the first question, even "dedicated" production lines are geared to
speedy production rather than careful wheel-building. "Trained
technicians"? What good wheel-building takes is a little time, and
reasonable technique.

A machine-built standard wheel will be true at first, but the spokes are
far too loose, and are not stress-relieved, and so will fail quickly.
This is not prejudice, but observation.

As for which ones do better, one would hope that the fancy "boutique"
wheels costing over $1000 per pair would do better. For me, though, that
is an untestable hypothesis, since I can build my own wheels for a small
fraction of the price, and they last a very long time.


wow, by that rationale, every car, washing machine, every computer,
every elevator motor, every air conditioning compressor, [insert any
number of mass production processes here] would be utter garbage. but
they're not.

don't believe all the fud. that's the i.q. vacuum into which ill
researched books get sold.