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Replacing a used front rim



 
 
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  #1  
Old October 17th 18, 03:36 PM posted to rec.bicycles.tech
Tanguy Ortolo
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Posts: 34
Default Replacing a used front rim

Hello all,

A couple of months ago, I noticed my rear rim was worn out, with some
scratches I attributed to braking with sand or gravel on the pads. I
therefore replaced the wheel, and noticed that at some points, the old
ril was almost pierced!

Now, I am noticing without surprise that it would be wise to replace my
front rim as well. Although it has no obvious scratch like the read one
had, its braking surface has developped a concavity I think it did not
had at the beginning, so I suppose it is the result of successive
braking.

Does it sound normal for rims to wear out after about 30 or 40 thousand
kilometers?

Now, since I am replacing it anyway, it will be a bit trickier than just
changing the wheel, because I have a hub dynamo. I will therefore have
to buy a new naked rim, (ligature the wheel spokes,) despoke the old
wheel, and respoke it with the new rim.

So, I have to choose a new rim, taking into account the following
parameters:
* rim dimensions and type: 622×19C;
* number of spoke holes: 36.

I there any other parameter I should take into account? Can I assume
that all 622 mm rims have spoke holes at the same distance from center?
Or in other words, that with keeping my hub and spokes, they will
correctly fit the new rim as long as it has the same diameter of 622 mm?

Cheers,

--
Tanguy
Ads
  #2  
Old October 17th 18, 04:13 PM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 3,417
Default Replacing a used front rim

On Wednesday, October 17, 2018 at 7:36:58 AM UTC-7, Tanguy Ortolo wrote:
Hello all,

A couple of months ago, I noticed my rear rim was worn out, with some
scratches I attributed to braking with sand or gravel on the pads. I
therefore replaced the wheel, and noticed that at some points, the old
ril was almost pierced!

Now, I am noticing without surprise that it would be wise to replace my
front rim as well. Although it has no obvious scratch like the read one
had, its braking surface has developped a concavity I think it did not
had at the beginning, so I suppose it is the result of successive
braking.

Does it sound normal for rims to wear out after about 30 or 40 thousand
kilometers?

Now, since I am replacing it anyway, it will be a bit trickier than just
changing the wheel, because I have a hub dynamo. I will therefore have
to buy a new naked rim, (ligature the wheel spokes,) despoke the old
wheel, and respoke it with the new rim.

So, I have to choose a new rim, taking into account the following
parameters:
* rim dimensions and type: 622×19C;
* number of spoke holes: 36.

I there any other parameter I should take into account? Can I assume
that all 622 mm rims have spoke holes at the same distance from center?
Or in other words, that with keeping my hub and spokes, they will
correctly fit the new rim as long as it has the same diameter of 622 mm?


Number of spokes and ERD, effective rim diameter. If the diameter of the new and old rims is more than a few mms different, then you need to get different spokes. To use the same spokes, you need the same number of holes and the same ERD, within a few mms.

-- Jay Beattie.
  #3  
Old October 17th 18, 07:04 PM posted to rec.bicycles.tech
Ned Mantei[_2_]
external usenet poster
 
Posts: 64
Default Replacing a used front rim

On 17-10-18 16:36, Tanguy Ortolo wrote:
Hello all,

A couple of months ago, I noticed my rear rim was worn out, with some
scratches I attributed to braking with sand or gravel on the pads. I
therefore replaced the wheel, and noticed that at some points, the old
ril was almost pierced!

Now, I am noticing without surprise that it would be wise to replace my
front rim as well. Although it has no obvious scratch like the read one
had, its braking surface has developped a concavity I think it did not
had at the beginning, so I suppose it is the result of successive
braking.

Does it sound normal for rims to wear out after about 30 or 40 thousand
kilometers?

Now, since I am replacing it anyway, it will be a bit trickier than just
changing the wheel, because I have a hub dynamo. I will therefore have
to buy a new naked rim, (ligature the wheel spokes,) despoke the old
wheel, and respoke it with the new rim.

So, I have to choose a new rim, taking into account the following
parameters:
* rim dimensions and type: 622×19C;
* number of spoke holes: 36.

I there any other parameter I should take into account? Can I assume
that all 622 mm rims have spoke holes at the same distance from center?
Or in other words, that with keeping my hub and spokes, they will
correctly fit the new rim as long as it has the same diameter of 622 mm?

Cheers,


I don't think rims have ever lasted 30,000 km for me. They become
concave from braking, and need to be replaced when the thickness is 1 mm
or less. Disastrous accidents can happen if the rim isn't replaced soon
enough.

Many rims have some sort of wear indicator, for example tiny holes that
disappear when the rim wears down enough. For this maybe check the
website of the company that produced the rim.

When looking for a new rim check tables with the ERD (effective rim
diameter) of various rims (google "rim erd database"). I would try for a
new rim such that the ERD is within 1 mm or so.

Jobst said that spokes should ≈always be reused, and that his were still
fine after about 100,000 miles. I have followed Jobst's advice for about
15 or 20 years, and never had a spoke break.

Concerning "despoking", in his book "The Bicycle Wheel", Jobst Brandt
said to move the spokes one at a time from the old to the new rim,
starting next to the valve holes. This works for me. Pay attention to
how the spoke holes are arranged on the rim: Often they alternate
between one side of the rim or the other, and you want the same
orientation on the new rim.

And then comes truing the wheel so that it's round, centered between the
hub locknuts, and the spokes have more or less even tension. I have no
routine with this, and even with a truing stand, a dish tool to check
for centering, and a tensiometer, it takes me about 3 hours to get the
wheel close enough. People who do this often probably need less than
half an hour. It helps if you have a good sense of pitch, so that you
can judge relative tension by the tone you hear when plucking a spoke.

I would suggest first reading up on this and/or watching some videos.

Ned
  #4  
Old Yesterday, 06:24 PM posted to rec.bicycles.tech
Tanguy Ortolo
external usenet poster
 
Posts: 34
Default Replacing a used front rim

Hello again,

Tanguy Ortolo, 2018-10-17 16:36+0200:
A couple of months ago, I noticed my rear rim was worn out, with some
scratches I attributed to braking with sand or gravel on the pads. I
therefore replaced the wheel, and noticed that at some points, the old
ril was almost pierced!

Now, since I am replacing it anyway, it will be a bit trickier than just
changing the wheel, because I have a hub dynamo. I will therefore have
to buy a new naked rim, (ligature the wheel spokes,) despoke the old
wheel, and respoke it with the new rim.


Thanks for all the advice, I have just done the work, taping the rims
together and moving spokes one by one from one rim to the new one.

This allowed me to pay attention to things that never really bothered me
before, like spoke lubrication, vertical truing, spoke torsion and
stress relief.

After the initial spoke tensionning, I had the pleasure to discover that
my new wheel was less than 1 mm out vertical and lateral true (or is it
trueness?), so I did not have to do much truing.

I will now monitor the wheel while I start using it. I must say it feels
quite good to ride on a wheel I built by myself!

--
Tanguy
  #5  
Old Yesterday, 07:45 PM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 5,536
Default Replacing a used front rim

On 2018-10-17 11:04, Ned Mantei wrote:


[...]

And then comes truing the wheel so that it's round, centered between the
hub locknuts, and the spokes have more or less even tension. I have no
routine with this, and even with a truing stand, a dish tool to check
for centering, and a tensiometer, it takes me about 3 hours to get the
wheel close enough. People who do this often probably need less than
half an hour. It helps if you have a good sense of pitch, so that you
can judge relative tension by the tone you hear when plucking a spoke.


A laptop with microphone and a spectrum analyzer display software or a
musical instrument tuning software can help those of us who, like
myself, have next to nothing in musical hearing abilities.

Such software is often free and the built-in microphone can suffice
which would make the investment $0.

This is how I tuned our piano which my wife used to play.


I would suggest first reading up on this and/or watching some videos.


Absolutely. Or swallow the pride and let a bike repair shop do it.

--
Regards, Joerg

http://www.analogconsultants.com/
  #6  
Old Yesterday, 08:14 PM posted to rec.bicycles.tech
Tosspot[_3_]
external usenet poster
 
Posts: 1,199
Default Replacing a used front rim

On 11/12/18 6:24 PM, Tanguy Ortolo wrote:
Hello again,

Tanguy Ortolo, 2018-10-17 16:36+0200:
A couple of months ago, I noticed my rear rim was worn out, with some
scratches I attributed to braking with sand or gravel on the pads. I
therefore replaced the wheel, and noticed that at some points, the old
ril was almost pierced!

Now, since I am replacing it anyway, it will be a bit trickier than just
changing the wheel, because I have a hub dynamo. I will therefore have
to buy a new naked rim, (ligature the wheel spokes,) despoke the old
wheel, and respoke it with the new rim.


Thanks for all the advice, I have just done the work, taping the rims
together and moving spokes one by one from one rim to the new one.

This allowed me to pay attention to things that never really bothered me
before, like spoke lubrication, vertical truing, spoke torsion and
stress relief.


Give yourself to the Dark Side. It is the only way...

snip
  #7  
Old Yesterday, 08:36 PM posted to rec.bicycles.tech
Ralph Barone[_4_]
external usenet poster
 
Posts: 172
Default Replacing a used front rim

Joerg wrote:
On 2018-10-17 11:04, Ned Mantei wrote:


[...]

And then comes truing the wheel so that it's round, centered between the
hub locknuts, and the spokes have more or less even tension. I have no
routine with this, and even with a truing stand, a dish tool to check
for centering, and a tensiometer, it takes me about 3 hours to get the
wheel close enough. People who do this often probably need less than
half an hour. It helps if you have a good sense of pitch, so that you
can judge relative tension by the tone you hear when plucking a spoke.


A laptop with microphone and a spectrum analyzer display software or a
musical instrument tuning software can help those of us who, like
myself, have next to nothing in musical hearing abilities.

Such software is often free and the built-in microphone can suffice
which would make the investment $0.

This is how I tuned our piano which my wife used to play.


The problem with this approach is that unless you are radial spoking, the
plucked spoke excites the resonant modes in the spokes that it crosses, and
you get a mishmash of resonances, only one of which you are affecting by
tightening/loosening the spokes. Theoretically it's a piece of cake, but
practically it's quite difficult.

I would suggest first reading up on this and/or watching some videos.


Absolutely. Or swallow the pride and let a bike repair shop do it.




  #8  
Old Yesterday, 09:16 PM posted to rec.bicycles.tech
Frank Krygowski[_4_]
external usenet poster
 
Posts: 6,316
Default Replacing a used front rim

On 11/12/2018 12:24 PM, Tanguy Ortolo wrote:

After the initial spoke tensionning, I had the pleasure to discover that
my new wheel was less than 1 mm out vertical and lateral true (or is it
trueness?)...


Maybe it should be "truth"?

so I did not have to do much truing.

I will now monitor the wheel while I start using it. I must say it feels
quite good to ride on a wheel I built by myself!


I've always found it to be very satisfying, too. Congratulations!



--
- Frank Krygowski
  #9  
Old Yesterday, 09:24 PM posted to rec.bicycles.tech
Joerg[_2_]
external usenet poster
 
Posts: 5,536
Default Replacing a used front rim

On 2018-11-12 11:36, Ralph Barone wrote:
Joerg wrote:
On 2018-10-17 11:04, Ned Mantei wrote:


[...]

And then comes truing the wheel so that it's round, centered between the
hub locknuts, and the spokes have more or less even tension. I have no
routine with this, and even with a truing stand, a dish tool to check
for centering, and a tensiometer, it takes me about 3 hours to get the
wheel close enough. People who do this often probably need less than
half an hour. It helps if you have a good sense of pitch, so that you
can judge relative tension by the tone you hear when plucking a spoke.


A laptop with microphone and a spectrum analyzer display software or a
musical instrument tuning software can help those of us who, like
myself, have next to nothing in musical hearing abilities.

Such software is often free and the built-in microphone can suffice
which would make the investment $0.

This is how I tuned our piano which my wife used to play.


The problem with this approach is that unless you are radial spoking, the
plucked spoke excites the resonant modes in the spokes that it crosses, and
you get a mishmash of resonances, only one of which you are affecting by
tightening/loosening the spokes. Theoretically it's a piece of cake, but
practically it's quite difficult.


That can happen if the microphone is too far away. I had good luck with
this method when re-dishing my rear wheel after having to switch from a
6-speed UG freehub to 7-speed HG. To pluck a spoke hard enough I used a
wood stick with a notch cut into a side at its tip, then pulling it.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/
  #10  
Old Yesterday, 10:13 PM posted to rec.bicycles.tech
AMuzi
external usenet poster
 
Posts: 9,755
Default Replacing a used front rim

On 11/12/2018 1:36 PM, Ralph Barone wrote:
Joerg wrote:
On 2018-10-17 11:04, Ned Mantei wrote:


[...]

And then comes truing the wheel so that it's round, centered between the
hub locknuts, and the spokes have more or less even tension. I have no
routine with this, and even with a truing stand, a dish tool to check
for centering, and a tensiometer, it takes me about 3 hours to get the
wheel close enough. People who do this often probably need less than
half an hour. It helps if you have a good sense of pitch, so that you
can judge relative tension by the tone you hear when plucking a spoke.


A laptop with microphone and a spectrum analyzer display software or a
musical instrument tuning software can help those of us who, like
myself, have next to nothing in musical hearing abilities.

Such software is often free and the built-in microphone can suffice
which would make the investment $0.

This is how I tuned our piano which my wife used to play.


The problem with this approach is that unless you are radial spoking, the
plucked spoke excites the resonant modes in the spokes that it crosses, and
you get a mishmash of resonances, only one of which you are affecting by
tightening/loosening the spokes. Theoretically it's a piece of cake, but
practically it's quite difficult.

I would suggest first reading up on this and/or watching some videos.


Absolutely. Or swallow the pride and let a bike repair shop do it.



" Theoretically it's a piece of cake, but practically it's
quite difficult."

+1
I have never found that useful.

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


 




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