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 |
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. |
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. |
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. |
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 |
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 |
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 |
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 |
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 |
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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