1. ## spoke calculation problem

I am building a trials wheel for a friend:
*Rockman single-wall rim with ERD of 543
*Try-All K2 hub with 45mm flanges and 36mm offset
32 spokes

if I plug that into a spoke calculator, i get 265mm spokes. however, the rim is super wide and the spoke holes are drilled pretty far apart across the rim. I think my calculation assumes that the spoke holes are in something close to a straight line. these holes are about 2 cm apart across the rim, which leads me to believe that I need slightly shorter spokes. is there a way to calculate this? there's little room for error considering this is a single-wall rim.

2. If you post up all the hub dimensions, I can show you the spoke calc.

Alternately, the way to get around offsets in a calculator that doesn't allow for them is to reduce the center-to-flange hub dimension. So if your center-to-flange for the hub is 36mm and your spoke holes are offset 1 cm (10mm) from the centerline of the rim, plug in a hub offset of 26mm to get the correct spoke length.

If you have the rim in hand it is definitely worth measuring the ERD yourself rather than relying on a mfr number.

3. This is straight forward trig ((265*265)-(10*10))^.5= 264.8 any reasonable combination of hubs and rims will be less than 1mm shorter. You can file down 2mm off the spokes use a diamond fingernail file less than 1 dollar to clean up the threads. There is about 1mm effective difference between wheelsmith and dt regular nipples so don't panic if it is a bit off.

4. Originally Posted by zerodish
This is straight forward trig ((265*265)-(10*10))^.5= 264.8 any reasonable combination of hubs and rims will be less than 1mm shorter. You can file down 2mm off the spokes use a diamond fingernail file less than 1 dollar to clean up the threads. There is about 1mm effective difference between wheelsmith and dt regular nipples so don't panic if it is a bit off.
wrong.
not so straight forward I guess.

example:
45mm flange
offset of 36mm
rim with an ERD of 540mm

the difference in spoke length is 1.1mm for a 10mm offset toward the flange versus ceterline drilled.

5. subscribed... I have the exact same question.

6. Originally Posted by CupOfJava
subscribed... I have the exact same question.
if the offset is toward the flange you are calculating, reduce the center-to-flange dimension by the offset. if the offset is away from the flange you're calculating, add it to the c-t-f.
if you post up all your dimensions I will run the calc for you (my calculator allows for input of offset).

7. I got this simple answer from the friendly folks at Tarty bikes:

You can simply measure the offset of the spoke hole from the centre of the rim, then subtract that number from the hub offsets

8. Originally Posted by mack_turtle
FIFY

9. You could also have just read the product description for this rim at tarty bikes. It says "- ERD: 543mm, spoke hole offset 9mm (for spoke calculation subtract 9mm from hub offsets)."

10. i didn't find that link until later, i got the photo from a google image search. my friend just handed me the rim and told me the ERD is 543. the answer was foolishly simple though.

11. ## spoke calculation problem

Originally Posted by zerodish
...You can file down 2mm off the spokes use a diamond fingernail file less than 1 dollar to clean up the threads. There is about 1mm effective difference between wheelsmith and dt regular nipples so don't panic if it is a bit off.
No, you can not just file down the spokes to shorten them. You will run out of threads.

I have never noticed any difference in DT and WS when building, and I have mixed them on the same wheel.

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