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Spoke threads exposed on new wheel - Safe?
Last night, I built a new rear wheel for cross riding using a Record
36 hole hubs, a Ritchey OCR Comp rim (called Trekking on web site) and DT 14/15 spokes. In doing the research, I noticed that Ritchey's web site gave the ERD as 596 mm whereas Damon Rinard's Spocalc gave it as 605 mm. Perhaps Ritchey has redesigned the rims? At any rate, I called Ritchey and the rep talked to a wheel builder who gave the ERD 599. Hmm... Right between the two values... I plugged the 599 value in Spocalc and built the wheel using 290's on the left and 288's on the right. At this point, I've tensioned them to 70 kg on the left and 115 on the right. On inspection, I noticed that the left side as 2-3 threads exposed all around whereas the right side has 5-6 threads exposed. I'm comcerned that the spokes are too short and I don't have enough threads embedded in the brass nipples. Is this wheel safe or should I rebuild it with longer spokes? Thx, Dave |
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Spoke threads exposed on new wheel - Safe?
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Spoke threads exposed on new wheel - Safe?
Alex Rodriguez wrote:
In article , says... Last night, I built a new rear wheel for cross riding using a Record 36 hole hubs, a Ritchey OCR Comp rim (called Trekking on web site) and DT 14/15 spokes. In doing the research, I noticed that Ritchey's web site gave the ERD as 596 mm whereas Damon Rinard's Spocalc gave it as 605 mm. Perhaps Ritchey has redesigned the rims? At any rate, I called Ritchey and the rep talked to a wheel builder who gave the ERD 599. Hmm... Right between the two values... I plugged the 599 value in Spocalc and built the wheel using 290's on the left and 288's on the right. At this point, I've tensioned them to 70 kg on the left and 115 on the right. On inspection, I noticed that the left side as 2-3 threads exposed all around whereas the right side has 5-6 threads exposed. I'm comcerned that the spokes are too short and I don't have enough threads embedded in the brass nipples. Is this wheel safe or should I rebuild it with longer spokes? I would rebuild with the proper length spoke. I sounds like your spokes are too short by a few mm. If you look at your spoke nipples you can see that they are not threaded all the way. About half the nipple is unthreaded. So if you can see exposed threads, there are more unexposed threads that are not engaging the nipple. --------------- Alex I agree with Alex. On the Spoke Calc site there is a way to measure ERD: Effective Rim Diameter (ERD) is the diameter on which you want the ends of the spokes to lie. Most people prefer it near the end of the spoke nipple. If you want to measure your own rim (recommended, just to be sure), then follow these instructions: Insert two old spokes into holes exactly opposite each other on the rim. Count holes to be sure. Screw some nipples onto the spokes. Pull them tight and measure dimension A in the figure (the diameter to the edge of the nipples, where the spokes dissapears into them). Do this at several spots around the rim and average the measurements. Measure the length of a nipple (dimension B in the figure) and add it twice (once for each nipple). The result is Effective Rim Diameter (ERD). Thus, ERD = A + 2B. Effective Rim Diameter (ERD) is the dimension you type into the spreadsheet for "ERD, effective rim diameter". Of all the dimensions you actually might measure, ERD is the most critical dimension affecting spoke length, so it makes sense to measure it a few times at different places around the rim. Always count to make sure you use spoke holes that are actually opposite each other! It is a pain to get the wheel built and find out the spokes aren't the correct length. The Ritchey PRO Trekker Girders I have measure ERD 605 mm. I used 294 mm right and 296 mm left. The spoke length came in fine on my Shimano XTR and DURA ACE hubs. -- David Ornee, Western Springs, IL USA David Ornee, Western Springs, IL USA -------------------------- Posted via cyclingforums.com http://www.cyclingforums.com |
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Spoke threads exposed on new wheel - Safe?
daveornee wrote:
I agree with Alex. On the Spoke Calc site there is a way to measure ERD: Effective Rim Diameter (ERD) is the diameter on which you want the ends of the spokes to lie. Most people prefer it near the end of the spoke nipple. If you want to measure your own rim (recommended, just to be sure), then follow these instructions: The OP has the advantage of an easy of way of calculating what size spokes to use for his rebuild: whatever size he used + the length of exposed thread! --Josh |
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Spoke threads exposed on new wheel - Safe?
Josh Gatts wrote in message om...
daveornee wrote: I agree with Alex. On the Spoke Calc site there is a way to measure ERD: Effective Rim Diameter (ERD) is the diameter on which you want the ends of the spokes to lie. Most people prefer it near the end of the spoke nipple. If you want to measure your own rim (recommended, just to be sure), then follow these instructions: The OP has the advantage of an easy of way of calculating what size spokes to use for his rebuild: whatever size he used + the length of exposed thread! --Josh Dear Josh, You practical devil! Even if there are objections that I can't imagine, I admire your approach. You probably know the apocryphal story of Edison asking a college graduate who wanted to work in his lab to determine the volume of an empty glass light bulb. After the slide-rule expert finished laboriously measuring curves and calculating an approximate answer, Edison taught him a practical lesson by filling the bulb with water, pouring the water into a graduated cylinder, and announcing the exact volume. Thanks, Carl Fogel |
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Spoke threads exposed on new wheel - Safe?
On Sat, 01 Nov 2003 01:52:20 GMT Josh Gatts
wrote: The OP has the advantage of an easy of way of calculating what size spokes to use for his rebuild: whatever size he used + the length of exposed thread! Rather than concentrate on the exposed thread, which is only part of the unengaged thread, he should measure from the other side of the spoke nipple. Measure how far down below the spoke head the end of the spoke stops. You can do this rather easily with a bit of wire, or a paper clip, or even screw in a loose spoke from above and count turns. - ----------------------------------------------- Jim Adney Madison, WI 53711 USA ----------------------------------------------- |
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Spoke threads exposed on new wheel - Safe?
"Jim Adney" wrote in message
... On Sat, 01 Nov 2003 01:52:20 GMT Josh Gatts wrote: The OP has the advantage of an easy of way of calculating what size spokes to use for his rebuild: whatever size he used + the length of exposed thread! Rather than concentrate on the exposed thread, which is only part of the unengaged thread, he should measure from the other side of the spoke nipple. Measure how far down below the spoke head the end of the spoke stops. You can do this rather easily with a bit of wire, or a paper clip, or even screw in a loose spoke from above and count turns. You could also measure the length of a nipple to the base of the slot (N), the length of the threading (T) on a spoke, and the length of exposed thread (E). If your existing spoke is length L, you buy spokes of length L + N - T + E. Heh heh. It's fun to come up with these things, but in reality a couple of unengaged threads aren't the end of the world (6 *exposed* threads, which is what the OP was talking about, are more than I would accept, though.) I would personally just do the easiest thing (the way I originally recommended, IMHO), and maybe add 1mm to account for the fact that the threads begin a little way into the nipple. I just noticed that Peter Chisholm has recommended just replacing the nips with 16mm. That's probably the best & cheapest solution, although it may look a little goofy. Thanks for the idears. --Josh |
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Spoke threads exposed on new wheel - Safe?
or (B): simply measure the depth of the hole from the bead diameter,
622-mm for a 700c. don't forget to 2x it. |
#9
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Spoke threads exposed on new wheel - Safe?
"B.C. Cletta" wrote:
or (B): simply measure the depth of the hole from the bead diameter, 622-mm for a 700c. don't forget to 2x it. Ooh, I never heard that one. Clever! Art Harris |
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Spoke threads exposed on new wheel - Safe?
B.C. Cletta wrote:
: or (B): simply measure the depth of the hole from the bead diameter, : 622-mm for a 700c. don't forget to 2x it. Is that 622mm consistent for different rims? When I swap my front and rear wheels on my truing stand, I have to adjust the vertical truing doohickey by about 1mm. - mark |
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