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Wheel building questions (OMG - a tech thread!)



 
 
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  #1  
Old January 11th 19, 03:04 AM posted to rec.bicycles.tech
Mark J.
external usenet poster
 
Posts: 537
Default Wheel building questions (OMG - a tech thread!)

Wheel building questions (including "religious" questions to replace the
political ones with which RBT has become saturated).

Background: I am re-rimming a wheel.
Hub: Powertap GS, 24 spoke (NOT disc)
Spokes: Sapim CX-ray bladed straight-pull
Old Rim: Velocity A23 O/C (offset) 700C non-eyeletted rim
New Rim: DT 411 (also offset), uses DT-supplied/mandated nipple washers.

Original build tension measured with a Park tensiometer, drive side
tensioned to Velocity's recommended max, even tension on each side.

Other: I'm ~170 lbs and strong enough though not as in days of yore, but
bike is geared quite low so on the steep stuff, the hub sees a fair bit
of torque. Tires 700x25, typically 105-110 psi. Paved road use except
for a handful of miles.

I built the original (Velocity) rim in 2015, had no problems until
recently (9900 miles later). Now I notice the rim starting to crack at
the spoke holes (only the pulling spokes on the drive side). Wheel was
still rideable and true when I unlaced it, so the cracks weren't severe yet.

NOTE: I KNOW (IMHO) that I'm pushing the margins with this build, so if
I can only get 10,000 miles and 3 years out of a wheel like this, I'm OK
with that, but I'll be happy to get more. I have plenty of more
durable/reliable wheels, but I've had fun with this wheel, and fun is
why we're here.

QUESTIONS:

Q1: I don't use thread compound or linseed oil, and would rather not
start now. I lubricate threads and nipple/washer contact with light
grease. What is a reasonable minimum non-drive-side tension to be
confident the spokes won't loosen?

I'm partway though tensioning the new rim, and think I can get the NDS
up to ~80 kgf if I push the DS up to DT's recommended max tension (1200
Newtons, or 122 kgf). I'm confident 80kgf is plenty on the NDS, but I
may want to put less than max tension on the DS (and thus less that 80
kgf on the NDS) to give me more margin on the cracking problem.

Q2: Do we suppose DT's (and/or Velocity's) max tension recommendation
has enough margin that stress-relieving the spokes won't overstress the
nipple holes? I reefed on the last build pretty hard at
stress-relieving time, Could that have weakened the rim in a way that
only showed up 10,000 miles later? I have belonged to the church of
stress-relieving for a long time, but my faith is weak.

Q3: (let the religious wars begin!) I would think that stress-relieving
is of primary benefit with J-bend spokes. Does it really help with
straight-pulls?

Notes: I have studied the sacred writings of the Jobst, on multiple
occasions, though I'll admit I'm having a hard time fully grokking his
stress-relieving argument.
I just did it 'cause "why not?" Now I'm quavering.
Also note that with bladed straight-pull spokes, any spoke wind-up would
be immediately obvious ('cause bladed), and anyway perhaps impossible
because the entire spoke, including the head, just turns on you.


Right now my inclination is to tension the DS at the recommended limit,
stress-relieve just a little less vigorously than last time, hope that
the nipple washers that DT mandates (and supplies) will spread out the
stress better at the nipple holes, expect at least 10k miles of
usefulness, and hope for more.

Thoughts? (esp. on questions Q1, Q2, and Q3 above)

Mark J.
Ads
  #2  
Old January 11th 19, 05:01 AM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 3,769
Default Wheel building questions (OMG - a tech thread!)

On Thursday, January 10, 2019 at 7:04:10 PM UTC-8, Mark J. wrote:
Wheel building questions (including "religious" questions to replace the
political ones with which RBT has become saturated).

Background: I am re-rimming a wheel.
Hub: Powertap GS, 24 spoke (NOT disc)
Spokes: Sapim CX-ray bladed straight-pull
Old Rim: Velocity A23 O/C (offset) 700C non-eyeletted rim
New Rim: DT 411 (also offset), uses DT-supplied/mandated nipple washers.

Original build tension measured with a Park tensiometer, drive side
tensioned to Velocity's recommended max, even tension on each side.

Other: I'm ~170 lbs and strong enough though not as in days of yore, but
bike is geared quite low so on the steep stuff, the hub sees a fair bit
of torque. Tires 700x25, typically 105-110 psi. Paved road use except
for a handful of miles.

I built the original (Velocity) rim in 2015, had no problems until
recently (9900 miles later). Now I notice the rim starting to crack at
the spoke holes (only the pulling spokes on the drive side). Wheel was
still rideable and true when I unlaced it, so the cracks weren't severe yet.

NOTE: I KNOW (IMHO) that I'm pushing the margins with this build, so if
I can only get 10,000 miles and 3 years out of a wheel like this, I'm OK
with that, but I'll be happy to get more. I have plenty of more
durable/reliable wheels, but I've had fun with this wheel, and fun is
why we're here.

QUESTIONS:

Q1: I don't use thread compound or linseed oil, and would rather not
start now. I lubricate threads and nipple/washer contact with light
grease. What is a reasonable minimum non-drive-side tension to be
confident the spokes won't loosen?

I'm partway though tensioning the new rim, and think I can get the NDS
up to ~80 kgf if I push the DS up to DT's recommended max tension (1200
Newtons, or 122 kgf). I'm confident 80kgf is plenty on the NDS, but I
may want to put less than max tension on the DS (and thus less that 80
kgf on the NDS) to give me more margin on the cracking problem.

Q2: Do we suppose DT's (and/or Velocity's) max tension recommendation
has enough margin that stress-relieving the spokes won't overstress the
nipple holes? I reefed on the last build pretty hard at
stress-relieving time, Could that have weakened the rim in a way that
only showed up 10,000 miles later? I have belonged to the church of
stress-relieving for a long time, but my faith is weak.

Q3: (let the religious wars begin!) I would think that stress-relieving
is of primary benefit with J-bend spokes. Does it really help with
straight-pulls?

Notes: I have studied the sacred writings of the Jobst, on multiple
occasions, though I'll admit I'm having a hard time fully grokking his
stress-relieving argument.
I just did it 'cause "why not?" Now I'm quavering.
Also note that with bladed straight-pull spokes, any spoke wind-up would
be immediately obvious ('cause bladed), and anyway perhaps impossible
because the entire spoke, including the head, just turns on you.


Right now my inclination is to tension the DS at the recommended limit,
stress-relieve just a little less vigorously than last time, hope that
the nipple washers that DT mandates (and supplies) will spread out the
stress better at the nipple holes, expect at least 10k miles of
usefulness, and hope for more.

Thoughts? (esp. on questions Q1, Q2, and Q3 above)

Mark J.


Velocity recommends 110-130kgf whether or not that stays true. That's why I use linseed oil now. I've cracked spoke holes on Aeroheads at those tensions.

-- Jay Beattie.
  #3  
Old January 11th 19, 01:26 PM posted to rec.bicycles.tech
Andre Jute[_2_]
external usenet poster
 
Posts: 8,994
Default Wheel building questions (OMG - a tech thread!)

On Friday, January 11, 2019 at 3:04:10 AM UTC, Mark J. wrote:

Q1: I don't use thread compound or linseed oil, and would rather not
start now. I lubricate threads and nipple/washer contact with light
grease.


The special feature of linseed oil is that it is a "drying oil", more particularly a "slow drying oil", so it will give the thread/nipple/rim interface lubrication during assembly, and then slowly reducing flexibility to settle in for a considerable period, up to six months, and over this period slowly evaporate to leave a residue that will eventually lock the joint. So linseed oil acts as thread locker but one working gradually, with reducing flexibility over time. Grease won't do that.

Linseed is fairly heavy oil. Other, lighter, drying oils include safflower oil, poppy oil, and walnut oil. You can get them all at any good art supplies store as they are used by oil fine art painters. But walnut oil from the supermarket is just as good and about a quarter the price of the art supply walnut oil.

Note that not all natural oils are drying oils.

I tried them all when I rebuilt wheels that arrived shoddily built from Gazelle. They all worked equally well and the wheels were still good and tight when I stopped riding that bike because I had a new favourite.

Read the labels in the art store carefully before you make your choice. You don't want any oils with resins in them: they dry fast and set hard. You may or may not want siccatives in your oil: they speed the drying but do not set hard like resin. You do not want volatiles (turpentine, white spirits) in your oil because they speed evaporation. If you go for the supermarket walnut oil, buy the one with the fewest additives, and don't buy any that are blended with other types of oil, because the other oil(s) could cause unforeseen effects.

***
You could even use ingredients you find in your wife's kitchen to make a very passable substitute for a drying oil. As Le Grande Jobst informed us, water is a lubricant. And your wife has raw eggs and olive oil in the kitchen.. Separate an egg yolk from the white goo. Discard the white stuff or feed it to the cat. Mix the yolk with twice its volume of olive oil, until it forms an emulsion. Keep the emulsion in the fridge in an airtight bottle because it will dry sooner than you can finish the wheel. Take out only enough to use in say half an hour. Add water to a small portion of the egg/oil emulsion until it flows like thin cream. This is what you use. The water and oil will lubricate the construction of the spokes into the wheel, and the egg will set over a period of weeks as first the water and then the olive oil evaporates, but after a couple of hours you will be able to move the spoke, so this is a faster process than any of the oils above, than even the resin. Basically, this is egg tempera (like artists used as paint until midway through the Renaissance) or more precisely tempera grassa, minus the pigment. I haven't tried it on bicycle spokes but I've used it on kaolin clay boards, and it makes a good hard surface.

Andre Jute
Sometimes I wish I paid attention in Chemistry class
  #4  
Old January 11th 19, 03:07 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 10,168
Default Wheel building questions (OMG - a tech thread!)

On 1/10/2019 9:04 PM, Mark J. wrote:
Wheel building questions (including "religious" questions to
replace the political ones with which RBT has become
saturated).

Background: I am re-rimming a wheel.
Hub: Powertap GS, 24 spoke (NOT disc)
Spokes: Sapim CX-ray bladed straight-pull
Old Rim: Velocity A23 O/C (offset) 700C non-eyeletted rim
New Rim: DT 411 (also offset), uses DT-supplied/mandated
nipple washers.

Original build tension measured with a Park tensiometer,
drive side tensioned to Velocity's recommended max, even
tension on each side.

Other: I'm ~170 lbs and strong enough though not as in days
of yore, but bike is geared quite low so on the steep stuff,
the hub sees a fair bit of torque. Tires 700x25, typically
105-110 psi. Paved road use except for a handful of miles.

I built the original (Velocity) rim in 2015, had no problems
until recently (9900 miles later). Now I notice the rim
starting to crack at the spoke holes (only the pulling
spokes on the drive side). Wheel was still rideable and
true when I unlaced it, so the cracks weren't severe yet.

NOTE: I KNOW (IMHO) that I'm pushing the margins with this
build, so if I can only get 10,000 miles and 3 years out of
a wheel like this, I'm OK with that, but I'll be happy to
get more. I have plenty of more durable/reliable wheels,
but I've had fun with this wheel, and fun is why we're here.

QUESTIONS:

Q1: I don't use thread compound or linseed oil, and would
rather not start now. I lubricate threads and nipple/washer
contact with light grease. What is a reasonable minimum
non-drive-side tension to be confident the spokes won't loosen?

I'm partway though tensioning the new rim, and think I can
get the NDS up to ~80 kgf if I push the DS up to DT's
recommended max tension (1200 Newtons, or 122 kgf). I'm
confident 80kgf is plenty on the NDS, but I may want to put
less than max tension on the DS (and thus less that 80 kgf
on the NDS) to give me more margin on the cracking problem.

Q2: Do we suppose DT's (and/or Velocity's) max tension
recommendation has enough margin that stress-relieving the
spokes won't overstress the nipple holes? I reefed on the
last build pretty hard at stress-relieving time, Could that
have weakened the rim in a way that only showed up 10,000
miles later? I have belonged to the church of
stress-relieving for a long time, but my faith is weak.

Q3: (let the religious wars begin!) I would think that
stress-relieving is of primary benefit with J-bend spokes.
Does it really help with straight-pulls?

Notes: I have studied the sacred writings of the Jobst, on
multiple occasions, though I'll admit I'm having a hard time
fully grokking his stress-relieving argument.
I just did it 'cause "why not?" Now I'm quavering.
Also note that with bladed straight-pull spokes, any spoke
wind-up would be immediately obvious ('cause bladed), and
anyway perhaps impossible because the entire spoke,
including the head, just turns on you.


Right now my inclination is to tension the DS at the
recommended limit, stress-relieve just a little less
vigorously than last time, hope that the nipple washers that
DT mandates (and supplies) will spread out the stress better
at the nipple holes, expect at least 10k miles of
usefulness, and hope for more.

Thoughts? (esp. on questions Q1, Q2, and Q3 above)

Mark J.


24h is probably less robust than a 32 but you have a 24h hub
so here we are.

Yes most of the effect of brief overtension after build is
to straighten/seat the spoke heads at the bend so I agree
you should see minimal change with a straight spoke. Still
and all, any slack ought to be taken up then.

We like linseed oil as it lubricates well during build and
after set will still move with a spoke wrench, unlike
anaerobic thread lockers. I built with oil for years but
that was back when rims were heavy and wheels were nearly
all 36h.

I can't quantify 'reef' but 'enough to seat spoke heads' may
be less than 'this is how strong I am'.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971


  #5  
Old January 20th 19, 03:49 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 28
Default Wheel building questions (OMG - a tech thread!)

On Thursday, January 10, 2019 at 10:04:10 PM UTC-5, Mark J. wrote:



Other: I'm ~170 lbs and strong enough though not as in days of yore, but
bike is geared quite low so on the steep stuff, the hub sees a fair bit
of torque. Tires 700x25, typically 105-110 psi. Paved road use except
for a handful of miles.


You shouldn't have any problems building a wheel that can handle 170# using those parts under most any conditions. The velocity rim probably wasn't a wise choice, but the DT with the nipple washers will be great.



QUESTIONS:

Q1: I don't use thread compound or linseed oil, and would rather not
start now. I lubricate threads and nipple/washer contact with light
grease. What is a reasonable minimum non-drive-side tension to be
confident the spokes won't loosen?

I'm partway though tensioning the new rim, and think I can get the NDS
up to ~80 kgf if I push the DS up to DT's recommended max tension (1200
Newtons, or 122 kgf). I'm confident 80kgf is plenty on the NDS, but I
may want to put less than max tension on the DS (and thus less that 80
kgf on the NDS) to give me more margin on the cracking problem.


I'd still stay wit the MFRs specs. Also, avoid _any_ abuse for the first hundred (at least) miles, including any efforts that exert high torque. As the wheel settles, of course the tension will drop, Stressing an under-tensioned wheel is a sure way to end up with a taco. Just give it a tune-up after every ride until the tension stops changing, then you can just do periodic maintenance.



Q2: Do we suppose DT's (and/or Velocity's) max tension recommendation
has enough margin that stress-relieving the spokes won't overstress the
nipple holes?


Velocity I don't know about, but I trust DT.

I reefed on the last build pretty hard at
stress-relieving time, Could that have weakened the rim in a way that
only showed up 10,000 miles later? I have belonged to the church of
stress-relieving for a long time, but my faith is weak.


I've never heard the term 'reef' in this context. but I'm assuming you mean the stress-releiveing process? Without quantifying what actual stresses you placed on the rim it's impossible to know. I will say that getting 10,000 miles on a rim with no reinforcement around the nipple isn't bad.


Q3: (let the religious wars begin!) I would think that stress-relieving
is of primary benefit with J-bend spokes. Does it really help with
straight-pulls?


It never hurts.


Notes: I have studied the sacred writings of the Jobst, on multiple
occasions, though I'll admit I'm having a hard time fully grokking his
stress-relieving argument.
I just did it 'cause "why not?" Now I'm quavering.
Also note that with bladed straight-pull spokes, any spoke wind-up would
be immediately obvious ('cause bladed), and anyway perhaps impossible
because the entire spoke, including the head, just turns on you.


Right now my inclination is to tension the DS at the recommended limit,
stress-relieve just a little less vigorously than last time, hope that
the nipple washers that DT mandates (and supplies) will spread out the
stress better at the nipple holes, expect at least 10k miles of
usefulness, and hope for more.


I completely agree with this.

Good luck.

 




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