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28 hole rim / 36 hole hub stuff



 
 
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  #1  
Old January 11th 06, 12:06 PM posted to rec.bicycles.tech
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Default 28 hole rim / 36 hole hub stuff

There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all. I read the "Perverse
Wheelbuilding" article on Sheldon's site
(http://www.sheldonbrown.com/mismatch/). My questions:
1. Has anyone built up any of these? Any insights that aren't mentioned
in the article?
2. Anyone built up any as rears, or as disc wheels? Anything exciting
happen if so?
3. Anyone have any insights about whether there would theoretically be
any problems with torsional strength using this lacing pattern as a
rear or disc wheel? My intuition is that I'm pretty sure it'd be fine
for normal rears, since most of the spokes are tangent and have angles
that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure
about as a disc wheel and wouldn't be too comfortable fudging it.

And just a disclaimer - I'm as into cool conventional wheels as all but
the grouchiest, and I know that 28 holes, unusual lacing patterns, and
the like are usually more gimmick than benefit. I'm mostly interested
in this because I keep seeing closeout 28 hole rims. I do think that in
general, 28 is fine if it's built right. Most of these rims are 26" as
well, which makes it less of an issue.

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  #2  
Old January 11th 06, 02:40 PM posted to rec.bicycles.tech
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Default 28 hole rim / 36 hole hub stuff

Nate Knutson wrote:
There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all. I read the "Perverse
Wheelbuilding" article on Sheldon's site
(http://www.sheldonbrown.com/mismatch/). My questions:
1. Has anyone built up any of these? Any insights that aren't mentioned
in the article?
2. Anyone built up any as rears, or as disc wheels? Anything exciting
happen if so?
3. Anyone have any insights about whether there would theoretically be
any problems with torsional strength using this lacing pattern as a
rear or disc wheel? My intuition is that I'm pretty sure it'd be fine
for normal rears, since most of the spokes are tangent and have angles
that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure
about as a disc wheel and wouldn't be too comfortable fudging it.

And just a disclaimer - I'm as into cool conventional wheels as all but
the grouchiest, and I know that 28 holes, unusual lacing patterns, and
the like are usually more gimmick than benefit. I'm mostly interested
in this because I keep seeing closeout 28 hole rims. I do think that in
general, 28 is fine if it's built right. Most of these rims are 26" as
well, which makes it less of an issue.


I'd say go for it! I'd use such a wheel even as a disc brake wheel or a
rear wheel.

Using the formula in _Bicycles and Tricycles_ I calculated the change
in tension for my 24 spoke disc brake tandem wheel. It's 25 pounds at
1g rate of decelleration, IIRC. I'm comfortable with that, since in
theory no spoke should go slack (minimum spoke tension is about 220
pounds) and max braking is very infrequent. Pedaling loads should be
less. We can stop a lot quicker than we can start. ;-) So far (about
500 miles) no problems at all.

  #3  
Old January 11th 06, 04:01 PM posted to rec.bicycles.tech
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Posts: n/a
Default 28 hole rim / 36 hole hub stuff


Nate Knutson wrote:
There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all.


28h hubs are not hard to find, niether are 36h(I know not your issue).


I read the "Perverse
Wheelbuilding" article on Sheldon's site
(http://www.sheldonbrown.com/mismatch/). My questions:
1. Has anyone built up any of these? Any insights that aren't mentioned
in the article?
2. Anyone built up any as rears, or as disc wheels? Anything exciting
happen if so?
3. Anyone have any insights about whether there would theoretically be
any problems with torsional strength using this lacing pattern as a
rear or disc wheel? My intuition is that I'm pretty sure it'd be fine
for normal rears, since most of the spokes are tangent and have angles
that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure
about as a disc wheel and wouldn't be too comfortable fudging it.

And just a disclaimer - I'm as into cool conventional wheels as all but
the grouchiest, and I know that 28 holes, unusual lacing patterns, and
the like are usually more gimmick than benefit. I'm mostly interested
in this because I keep seeing closeout 28 hole rims. I do think that in
general, 28 is fine if it's built right. Most of these rims are 26" as
well, which makes it less of an issue.


  #5  
Old January 11th 06, 05:52 PM posted to rec.bicycles.tech
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Posts: n/a
Default 28 hole rim / 36 hole hub stuff

On 11 Jan 2006 03:06:55 -0800, "Nate Knutson"
wrote:

There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all.


Decent but inexpensive 28 hole hubs are not as common used as 32 or
36, it's true, since performance-oriented 28-spoke wheels over 20"
have neither been common for as long nor as popular as the others. I
note that someone on eBay is trying very hard to dump a pile of 28h
coaster brake hubs. With a little perseverance, though, a pair of
hubs could doubtless be had...but with a little shopping around, I
suspect that you could come up with just as good of a deal on a 32h or
36h setup.

I read the "Perverse
Wheelbuilding" article on Sheldon's site
(http://www.sheldonbrown.com/mismatch/). My questions:
1. Has anyone built up any of these? Any insights that aren't mentioned
in the article?


It's a bit of a pain in the neck to do because of the various lengths
of spoke needed, and there is no way that you can do it with equal
spoke tension. As a result, under load, the wheel is likely to
experience cyclic lateral deflection in the area where the greatest
spoke unloading occurs, which is in the area of road contact. Since
this is not in a location where the deflection will cause any frame or
brake rub, it could perhaps be ignored...but in my opinion, it should
give you a clue about the likely long-term durability of the product.

2. Anyone built up any as rears, or as disc wheels? Anything exciting
happen if so?


Given the known need for unequal left/right tension, and the already
noted uneven tension within a side in the wheel under discussion, I
believe that this is a bad idea. It is likely that the wheel would be
difficult to get true and properly dished with adequate spoke tension
everywhere..

3. Anyone have any insights about whether there would theoretically be
any problems with torsional strength using this lacing pattern as a
rear or disc wheel? My intuition is that I'm pretty sure it'd be fine
for normal rears, since most of the spokes are tangent and have angles
that (I think) are similar to a 3x or 2x rear wheel, but I'm not sure
about as a disc wheel and wouldn't be too comfortable fudging it.


Braking forces are seldom at the magnitude of forward accelerations in
a low gear on a hill. If the wheel will function under acceleration,
it will have no problem with braking. The use of disc brakes is,
therefore, irrelevant except for the fact that the typical disc hub
has less flange offset than a rim-brake hub. In theory, this might
actually make the proposed rear wheel easier to attempt since the
left/right spoke tension imbalance is reduced, but it still looks like
a bad idea.

And just a disclaimer - I'm as into cool conventional wheels as all but
the grouchiest, and I know that 28 holes, unusual lacing patterns, and
the like are usually more gimmick than benefit. I'm mostly interested
in this because I keep seeing closeout 28 hole rims. I do think that in
general, 28 is fine if it's built right. Most of these rims are 26" as
well, which makes it less of an issue.


It's not hard to find 28-hole hubs. If you want to build a bargain
wheel that's worth riding, match the hub to the rim and build it
conventionally. Making a mismatch can be an interesting exercise when
you have scrap bits lying around and nothing better to do, but when
the object is to build a finished product that you're going to ride,
the better plan is to stick with what's designed to work properly.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
  #6  
Old January 11th 06, 06:37 PM posted to rec.bicycles.tech
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Default 28 hole rim / 36 hole hub stuff

The prices I'm talking about are in the $5-10US range for relatively
high end rims that originally were in the $45-60 range. Lots and lots
of this is available, seemingly all the time. The same isn't really
true for 28H hubs.

  #7  
Old January 11th 06, 08:39 PM posted to rec.bicycles.tech
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Default 28 hole rim / 36 hole hub stuff

On 11 Jan 2006 09:37:44 -0800, "Nate Knutson"
wrote:

The prices I'm talking about are in the $5-10US range for relatively
high end rims that originally were in the $45-60 range. Lots and lots
of this is available, seemingly all the time. The same isn't really
true for 28H hubs.


Any time you see last season's Hot Thing getting dumped cheap,
consider the concept that if it was really all that good of a product,
there would have been adequate demand for it to keep that from taking
place.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
  #8  
Old January 11th 06, 10:41 PM posted to rec.bicycles.tech
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Posts: n/a
Default 28 hole rim / 36 hole hub stuff

In article . com, Nate
Knutson wrote:

There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all. I read the "Perverse
Wheelbuilding" article on Sheldon's site
(http://www.sheldonbrown.com/mismatch/). My questions:
1. Has anyone built up any of these? Any insights that aren't mentioned
in the article?


I haven't used the approach outlined in sheldonbrown.com/mismatch, but
I've built up wheels with mismatched hubs and rims[1]. My advice: if
the purpose is the project itself, go ahead; if it's to build a durable
wheel, where possible, use components designed for each other.


Luke



1.
http://groups.google.ca/group/rec.bi.../thread/ced77b
f71f69de4e/eca63d2eebf1b21b?q=mismatched+hub+rim+luke&rnum=1# eca63d2eebf
1b21b

or

http://tinyurl.com/c9q8s
  #9  
Old January 12th 06, 01:42 AM posted to rec.bicycles.tech
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Posts: n/a
Default 28 hole rim / 36 hole hub stuff

Werehatrack wrote:
On 11 Jan 2006 03:06:55 -0800, "Nate Knutson"
wrote:

There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all.


[...] and there is no way that you can do it with equal
spoke tension. As a result, under load, the wheel is likely to
experience cyclic lateral deflection in the area where the greatest
spoke unloading occurs, which is in the area of road contact.


How can uneven spoke tension cause uneven rim deflection? If the spoke
is tight enough not to reach zero, then why would the stiffness be any
different to a wheel with evenly tensioned spokes?

2. Anyone built up any as rears, or as disc wheels? Anything exciting
happen if so?


Given the known need for unequal left/right tension, and the already
noted uneven tension within a side in the wheel under discussion, I
believe that this is a bad idea. It is likely that the wheel would be
difficult to get true and properly dished with adequate spoke tension
everywhere..


My experience with 24 spokes in a 36H hub was easy. Sure, there are
uneven tensions, but I don't see an issue with that in practice.
There's a range of tension in any tensioned spoked wheel. The loosest
spoke only has to be tight enough, then the tightest spoke is what it
is. The range in a strange wheel might be a bit larger, but other than
theoretically shorter rim life (due to the higher tension in the
tightest spoke) there's no functional down side I see. Am I missing
something?

3. Anyone have any insights about whether there would theoretically be
any problems with torsional strength using this lacing pattern as a
rear or disc wheel?


Braking forces are seldom at the magnitude of forward accelerations in
a low gear on a hill.


This is opposite my hunch, but I admit we might be coming at this from
different assumptions. I've always observed quicker rates of
deceleration than acceleration, but it's not been gauged. It's be nice
to make some measurements of accelerations/decelerations to find out.
For example, I can stop hard eough to raise the rear tire, but I can't
pedal hard enough to raise the front tire (unless I also jerk on the
bars).

[...T]he typical disc hub
has less flange offset than a rim-brake hub. In theory, this might
actually make the proposed rear wheel easier to attempt since the
left/right spoke tension imbalance is reduced,


Right, this is important to consider on any front disc wheel: no doubt
the front hub's disc-side flange is closer to center than a similar
non-disc brake hub's. But the rear hub's disc-side flange (on hubs I've
checked, anyway) has about the same offset as the non-disc version, so
for me it wouldn't normally be a consideration for the rear wheel.

  #10  
Old January 12th 06, 07:39 AM posted to rec.bicycles.tech
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Posts: n/a
Default 28 hole rim / 36 hole hub stuff

On 11 Jan 2006 16:42:04 -0800, wrote:

Werehatrack wrote:
On 11 Jan 2006 03:06:55 -0800, "Nate Knutson"
wrote:

There are some really deeply discounted, nice 28 hole rims around. I'd
like to use some to build up some cheap wheels, but of course there
aren't many 28 hole hubs laying around at all.


[...] and there is no way that you can do it with equal
spoke tension. As a result, under load, the wheel is likely to
experience cyclic lateral deflection in the area where the greatest
spoke unloading occurs, which is in the area of road contact.


How can uneven spoke tension cause uneven rim deflection? If the spoke
is tight enough not to reach zero, then why would the stiffness be any
different to a wheel with evenly tensioned spokes?


The spokes adjacent to the lowest-tension ones will be at a higher
tension, *and* on the other side in some areas. Ordinarily, it all
balances out to enough of a degree that it doesn't matter. With the
oddball lacing and the resulting variances in spoke tension, there
might well be some reaching zero at times.

2. Anyone built up any as rears, or as disc wheels? Anything exciting
happen if so?


Given the known need for unequal left/right tension, and the already
noted uneven tension within a side in the wheel under discussion, I
believe that this is a bad idea. It is likely that the wheel would be
difficult to get true and properly dished with adequate spoke tension
everywhere..


My experience with 24 spokes in a 36H hub was easy. Sure, there are
uneven tensions, but I don't see an issue with that in practice.


24 on a 36 doesn't require the kind of screwy lacing pattern cited for
the one in question, though. Four of the spokes end up being radial
in a 28 on 36 lash-up.

There's a range of tension in any tensioned spoked wheel. The loosest
spoke only has to be tight enough, then the tightest spoke is what it
is. The range in a strange wheel might be a bit larger, but other than
theoretically shorter rim life (due to the higher tension in the
tightest spoke) there's no functional down side I see. Am I missing
something?


Look at the lacing pattern cited. Tension variances will be large.

3. Anyone have any insights about whether there would theoretically be
any problems with torsional strength using this lacing pattern as a
rear or disc wheel?


Braking forces are seldom at the magnitude of forward accelerations in
a low gear on a hill.


This is opposite my hunch, but I admit we might be coming at this from
different assumptions. I've always observed quicker rates of
deceleration than acceleration, but it's not been gauged. It's be nice
to make some measurements of accelerations/decelerations to find out.
For example, I can stop hard eough to raise the rear tire, but I can't
pedal hard enough to raise the front tire (unless I also jerk on the
bars).


I, on the other hand, can kick the front wheel well into the air by
merely standing to pedal in the 26/28 combo. Also, on a rear wheel,
if you apply enough brake to begin to approach max pedalling torque,
the weight transfer forward unloads the wheel, and the tire slides.


--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.
 




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