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Replacing a used front rim



 
 
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  #1  
Old October 17th 18, 01:45 PM posted to rec.bicycles.tech
Tanguy Ortolo
external usenet poster
 
Posts: 36
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:

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
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  #2  
Old October 17th 18, 02:58 PM posted to rec.bicycles.tech
JBeattie
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Posts: 3,429
Default Replacing a used front rim

On Wednesday, October 17, 2018 at 5:46:00 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:

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?


What is normal depends on riding conditions. I work with a man who was replacing rims every two years or less. He does about 5-6,000 miles a year, almost all commuting and many miles in the rain. He is also heavy. He switched to a disc brake bike a few years ago. I got better life out of my rims, but I switched to discs 12 years ago on my commuter. Rain and road grit or mud can score up and grind down your rims. My fast bike has rim brakes and it is basically a dry weather bike.

-- Jay Beattie.
  #3  
Old October 17th 18, 08:22 PM posted to rec.bicycles.tech
Tosspot[_3_]
external usenet poster
 
Posts: 1,202
Default Replacing a used front rim

On 10/17/18 2:45 PM, 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?


Done a lot better than some of mine.

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:

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?


No. The effective rim diameter is very much dependent on rim model, so
you need to look it up. A quick start might be;

https://www.prowheelbuilder.com/spokelengthcalculator

So, pick a rim you like, get the ERD, then calculate the spoke length
for the ERD and hub you have.

All said and done, the tolerances are usually about 2mm, so don't sweat
it too much.


  #4  
Old October 17th 18, 09:01 PM posted to rec.bicycles.tech
JBeattie
external usenet poster
 
Posts: 3,429
Default Replacing a used front rim

On Wednesday, October 17, 2018 at 12:22:49 PM UTC-7, Tosspot wrote:
On 10/17/18 2:45 PM, 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?


Done a lot better than some of mine.

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:

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?


No. The effective rim diameter is very much dependent on rim model, so
you need to look it up. A quick start might be;

https://www.prowheelbuilder.com/spokelengthcalculator

So, pick a rim you like, get the ERD, then calculate the spoke length
for the ERD and hub you have.

All said and done, the tolerances are usually about 2mm, so don't sweat
it too much.


And assuming available ERDs are correct. You can get three or four different ERDs for some old rims, like Mavic MA2s -- from different sources, none directly from Mavic. http://velobase.com/ViewComponent.as...e-837eb8b21b0e I take the average. Then I try to find some modern rim with the same ERD -- which is not easy because everyone is trending to deep section or aero. You usually end up with some boat anchor from Sun or Alex -- or you pay through the nose for some modern clone. https://www.universalcycles.com/shop...4&category=139

I'm lucky to have Universal in town. They have a real rim inventory. Finding rims has become a lot more difficult over the last 30 years.

-- Jay Beattie.

  #5  
Old October 18th 18, 01:21 AM posted to rec.bicycles.tech
Steve Weeks
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Posts: 5
Default Replacing a used front rim

As others have noted, the "Effective Rim Diameter" (ERD) may vary widely among rims with the same "Bead Seat Diameter" (BSD). Only (*ONLY*) if you find a replacement rim with a BSD that is within a millimeter or two (at the most) will you be able to transfer spokes. Otherwise, you're talking about rebuilding the wheel.
This is not terribly difficult, but you should get a book about wheelbuilding to give yourself a better idea of what you are getting into. I recommend Roger Musson's book "Wheel Building". It's available at http://petitdragon999.free.fr/VTT/Ro...uilding-v5.pdf
Ideally, you would purchase the book; it's only about $12 dollars or so. It contains a lot of good information, not least how to measure the ERD.
I've used this book to successfully build front and rear wheels for my 700c road bike, and rear wheels for my 20" folder. I've never worn a front rim out, but my folder wears out the rear rim about every 2,000 miles. I've invested in an inexpensive truing stand (Spin Doctor) and a modestly priced spoke tension gauge (Park Tools), plus the usual spoke wrenches and a nipple driver (sounds painful).
Wheel building is fun!
Steve
  #6  
Old October 18th 18, 07:39 AM posted to rec.bicycles.tech
Ned Mantei[_2_]
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Posts: 64
Default Replacing a used front rim

On 17-10-18 22:01, jbeattie wrote:
And assuming available ERDs are correct. You can get three or four different ERDs for some old rims, like Mavic MA2s -- from different sources, none directly from Mavic.http://velobase.com/ViewComponent.as...e-837eb8b21b0e I take the average. Then I try to find some modern rim with the same ERD -- which is not easy because everyone is trending to deep section or aero. You usually end up with some boat anchor from Sun or Alex -- or you pay through the nose for some modern clone.https://www.universalcycles.com/shop...4&category=139


Finding a replacement rim has also become more difficult for a bike with
26-inch wheels. Newer mountain bikes usually have 27.5 or 29-inch
wheels, so for the typical supplier the selection of 26-inchers has
declined.

Ned
  #7  
Old October 18th 18, 08:06 AM posted to rec.bicycles.tech
Sir Ridesalot
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Posts: 3,765
Default Replacing a used front rim

On Thursday, October 18, 2018 at 2:39:56 AM UTC-4, Ned Mantei wrote:
On 17-10-18 22:01, jbeattie wrote:
And assuming available ERDs are correct. You can get three or four different ERDs for some old rims, like Mavic MA2s -- from different sources, none directly from Mavic.http://velobase.com/ViewComponent.as...e-837eb8b21b0e I take the average. Then I try to find some modern rim with the same ERD -- which is not easy because everyone is trending to deep section or aero. You usually end up with some boat anchor from Sun or Alex -- or you pay through the nose for some modern clone.https://www.universalcycles.com/shop...4&category=139


Finding a replacement rim has also become more difficult for a bike with
26-inch wheels. Newer mountain bikes usually have 27.5 or 29-inch
wheels, so for the typical supplier the selection of 26-inchers has
declined.

Ned


I often see nice looking 700C rims on the web but a great many of them are 32 holes not 36 holes. It seems that 36 holes rims are getting scarcer too.

Cheers
  #8  
Old October 18th 18, 09:29 AM posted to rec.bicycles.tech
Tanguy Ortolo
external usenet poster
 
Posts: 36
Default Replacing a used front rim

Thank you all for the advice, I will carefully check the effective rim
diameter.

Now, since I am keeping the old hub, that contains a dynamo, and the
spokes, I will not exactly be building a wheel, just changing the rim.
To do this, a colleague of mine suggested a tip he used for doing the
same: attaching spokes together with some tape, everywhere they cross.
Then, after unscrewing the nipples, the rim can be removed while the
spokes stay in position. This way, the new rim can be positionned, and
nipples screwed back without having to position spokes one by one.

I will tell you how it turns out.

--
Tanguy
  #9  
Old October 18th 18, 09:54 AM posted to rec.bicycles.tech
Sir Ridesalot
external usenet poster
 
Posts: 3,765
Default Replacing a used front rim

On Thursday, October 18, 2018 at 4:29:11 AM UTC-4, Tanguy Ortolo wrote:
Thank you all for the advice, I will carefully check the effective rim
diameter.

Now, since I am keeping the old hub, that contains a dynamo, and the
spokes, I will not exactly be building a wheel, just changing the rim.
To do this, a colleague of mine suggested a tip he used for doing the
same: attaching spokes together with some tape, everywhere they cross.
Then, after unscrewing the nipples, the rim can be removed while the
spokes stay in position. This way, the new rim can be positionned, and
nipples screwed back without having to position spokes one by one.

I will tell you how it turns out.

--
Tanguy


The best way to switch a rim of equal ERD with an old one is to tape the new rim to the old rim and then just move each spoke from the old rim to the new rim as you undo each spoke from t he old rim.

Cheers
  #10  
Old October 18th 18, 06:06 PM posted to rec.bicycles.tech
Ned Mantei[_2_]
external usenet poster
 
Posts: 64
Default Replacing a used front rim

On 18-10-18 10:54, Sir Ridesalot wrote:
On Thursday, October 18, 2018 at 4:29:11 AM UTC-4, Tanguy Ortolo wrote:
Thank you all for the advice, I will carefully check the effective rim
diameter.

Now, since I am keeping the old hub, that contains a dynamo, and the
spokes, I will not exactly be building a wheel, just changing the rim.
To do this, a colleague of mine suggested a tip he used for doing the
same: attaching spokes together with some tape, everywhere they cross.
Then, after unscrewing the nipples, the rim can be removed while the
spokes stay in position. This way, the new rim can be positionned, and
nipples screwed back without having to position spokes one by one.

I will tell you how it turns out.

--
Tanguy


The best way to switch a rim of equal ERD with an old one is to tape the new rim to the old rim and then just move each spoke from the old rim to the new rim as you undo each spoke from t he old rim.

Cheers


Good advice. And while doing this, as I mentioned earlier be sure that
the orientation of the two rims is the same: The spoke holes often
alternate right-left rather than being exactly at the midline. Also line
up the valve holes.

Ned
 




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