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  1. #1
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    WTB Frequency 19 rim ERD Question

    Hi Everyone,

    I'm working to lace up some WTB frequency i19 rims and per WTB the ERD is 603 mm. If I measure the ERD i get 621-622 mm using the method of two spokes at 200mm with two nipples, seat the two spokes then meausre the distance in between the spokes and add 400mm. If you look at the WTB faq for this rim it shows that the rim is 622 mm but the ERD is 603. So my question is how reliable is this method of measuring ERD if it isn't accurate for this type of rim? Does anyone use this method for other rims without issue? Thanks for any thoughts or suggestions.

    WTB Faq page 5: ww.wtb.com/pdf/wheeltech/frequency_rim_faq.pdf

  2. #2
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    I always use this method and haven't had an issue before. 621 or 622mm seems pretty big for an ERD, and the 603 seems like a more reasonable number.

    The only thing I can suggest is to remeasure the two spokes you are sing to verify they are 200mm. Then make sure that the nipples are fully seated in the rim. Finally, make multiple measurements at different areas on the rim.

    Let me know if you figure out what the problem is because I am curious myself.

  3. #3
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    Thanks for the reply, i have double checked the measurements at 200 and ensured they are seated. Is it strange that the measurement i get matches the measurement from WTB for the rim but then they provide this other number at 603. So maybe the method i'm using is just not very accurate but it seems to be the method many people use. I'm not sure what i'm doing wrong.

  4. #4
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    I use that method without issue when building wheels.

    Consider a few things:

    1) The top of the spoke should be equal with the bottom of the slot in the nipple.

    2) You are measuring from opposed holes, and

    3) You are measuring from the spoke bed, not the rim bed

  5. #5
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    OK, the 1st two i have confirmed, your third point i don't quite follow, can you elaborate ? what is the spoke bed versus the rim bed? I appreciate the feedback and help!

  6. #6
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    622 is the bead seat diameter. It is physically impossible to build a 700C wheel with a BSD that big. The ERD should be smaller than that.

    The third point: make sure the nipples come through the rim and don't stop at the first wall (outer).

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