Re: Can I build up a Dura-Ace hub with 15/16 DB spokes?
Steve Freides
-S-
Tom B. wrote:
> I've gone back over the FAQ (and the relevant sections in Jobst's
> book) and am still unclear on this point. Specifically, whether hubs
> that are drilled for a snug fit with 2.0 mm spoke ends (14 ga) will
> work for 1.8 mm spoke ends (15 ga).
>
> I bought all these parts in 2004-2005 (thank you Bike Nashbar for
> labeling all your items with date/price/etc. when they ship -- great
> idea!). DT spokes and Velocity Fusion rims were new, D-A hubs were
> NOS off ebay, model 7700 from the 9-speed era.
>
> I built one rear wheel right away, 32h 3x, 14/15 drive side, 15/16
> non- drive, brass nipps. I weigh about 165. After ~3000 mi of mostly
> mountains (this is my S&S travel bike), I started having spoke
> breakage on the non-drive side at the elbows. I've had about 8 of
> them break so far in ~5000 miles.
>
> Now I want to build the other wheel up, and I have all those same
> parts in hand. I just want to fix whatever I did wrong with the
> previous wheel. On that one, I brought the drive side tension up to
> ~120 kgF (not sure how to spell these units), even tone across each
> side, and never had any slackness/trueness problems until/unless a
> spoke broke.
>
> I squeezed them hard to stress relieve per the Jobst method. I did my
> best to press the outbound spokes into the flanges before tensioning.
> But they still broke.
>
> So I'm thinking my problem could have been one or more of the
> following:
>
> 1) I did not squeeze hard enough when stress relieving, or maybe I
> should consider Sheldon's "lever" (crank arm) technique, or just
> overall need to re-learn the process
>
> 2) I used spokes from a bad run out of DT (didn't they have a period
> of time when their elbow length had changed and caused breakage? and
> then they fixed things later)
>
> 3) I didn't form the spoke elbows to fit the flanges properly
>
> 4) I failed to buy and use washers when I needed to
>
> 5) As an extension of the previous thought, maybe 15/16 is just hard
> to do right on a D-A hub (nice snug fit in the flanges for 14 ga, much
> looser for 15 ga)
>
>
> I've already laced up the new wheel as before, and now I have my last
> chance to stress-relieve properly. But if 15/16 is doomed in this
> hub, then I can re-lace with 14/15 for non-drive. I hope that's not
> necessary.
>
> Thanks for any help.
>
> -Tom
Michael Press
<9f844737-f6dc-4230...@u26g2000yqu.googlegroups.com>,
"Tom B." <tom.b...@gmail.com> wrote:
rec.bicycles.tech added to the distribution.
Item 3) is a definite candidate.
After lacing and before tensioning,
look to see if the spoke has a fair lead
out of the hub flange. If not, give it
a bend so that it does. Same for the
spoke at the nipples, where you would
give it a bend with some round nose pliers.
I cannot comment on the other candidates.
--
Michael Press
Tom B.
> Please ask on rec.bicycles.tech.
>
Sorry about that; issued a delete post request about 1 minute after I
posted but it must have been too late.
Anton Berlin
The important question is can the wheel survive a 40 mph descent and
will your life insurance pay your estate for what could be easily
described as suicidal stupidity.
if you want a strong low spoke wheel buy an H3. Or buy one like
Cavendish uses, (used) that folds during a sprint for no good
reason.
Beloved Fred No. 1
Or one with carbon spokes.
Tom B.
> In article
> <9f844737-f6dc-4230-a5a6-917b29b5c...@u26g2000yqu.googlegroups.com>,
Thanks for the advice. I agree that the time to visually inspect is
before tensioning. I didn't see anything unusual at that time; just a
very tiny gap between the spoke and the flange, which I think is
normal? (I've never _not_ seen this) Unless you are saying that the
spoke should be formed to be perfectly flush with the entire height of
the flange at this time? That seems quite hard to do, at least
without a block of wood or similar to press with.
I have brought the wheel up to almost final tension now. I mentioned
in an earlier response that I was considering using a block of wood,
now, at this point, to press on the elbows/flanges (followed by more
stress relief squeezing/pressing, or whatever the consensus is that
this should be called). I don't know if this is good or neutral to
do. I don't think it would be bad.
Michael Press
<818d511c-58e4-4839...@x25g2000yqj.googlegroups.com>,
"Tom B." <tom.b...@gmail.com> wrote:
Yes, it is a good thing. Spokes break from fatigue.
Fatigue comes from stressing the metal near its
plastic yield point. A spoke that does not have
a fair lead out of the hub has permanent additional
stress that does not help the spoke do its job,
but does bring it closer to its yield point so
that it fatigues faster. Think of bending steel
clothes hanger wire back and forth until it breaks.
--
Michael Press
James
> Yes, it is a good thing. Spokes break from fatigue.
> Fatigue comes from stressing the metal near its
> plastic yield point. A spoke that does not have
> a fair lead out of the hub has permanent additional
> stress that does not help the spoke do its job,
> but does bring it closer to its yield point so
> that it fatigues faster. Think of bending steel
> clothes hanger wire back and forth until it breaks.
One of the reasons I like straight pull spokes. No bend means no
stress raiser.
JS.
thirty-six
Jump on the spokes to get the tension high enough and pray that the
rim does not give way. With a shallow rim you have no choice, the
wheel buckles.
thirty-six
Well take them to bed with you.
> Fatigue comes from stressing the metal near its
> plastic yield point.
Low cycle fatigue, irrelevant.
> A spoke that does not have
> a fair lead out of the hub has permanent additional
> stress that does not help the spoke do its job,
> but does bring it closer to its yield point so
> that it fatigues faster. Think of bending steel
> clothes hanger wire back and forth until it breaks.
Duh, stop the bending!
>
> --
> Michael Press