Spoke Length Calculator for Straight Pull & Internal Nips?

Discuss light weight issues concerning road bikes & parts.
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kresyzig
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Joined: Sat Apr 16, 2011 8:49 pm
Location: Ottawa, ON, Canada

by kresyzig

Hi,

is there a spoke length calculator that supports both straight pull spokes and internal nipples right of the bath?

Thanks!

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ergott
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by ergott

Internal nips are no problem. It's just getting the correct ERD which usually factors this in. For example, the ERD on Enve's website is for internal nipples.

There is no calc for straight pull hubs. If there is a cross pattern, each hub will have a slightly different calulation due to the flange thickness. I was able to use 2.65 for the 2X pattern on the drive side of the Zipp 188 straight pull hubs. That same number will not work for other straight pull hubs. If you are working with radial, there is no difference in the calculation.

-Eric

kresyzig
Posts: 222
Joined: Sat Apr 16, 2011 8:49 pm
Location: Ottawa, ON, Canada

by kresyzig

ergott wrote:Internal nips are no problem. It's just getting the correct ERD which usually factors this in. For example, the ERD on Enve's website is for internal nipples.

There is no calc for straight pull hubs. If there is a cross pattern, each hub will have a slightly different calulation due to the flange thickness. I was able to use 2.65 for the 2X pattern on the drive side of the Zipp 188 straight pull hubs. That same number will not work for other straight pull hubs. If you are working with radial, there is no difference in the calculation.

-Eric


Thanks. This is for that rear wheel I described in a previous thread. The wheel has been poorly built and needs to be rebuilt. Would it be accurate if I measured the length of the current spokes from the head up to the rim, then add the rim thickness and the nipple height to this measurement to get the spoke length I need?

Otherwise I could do the calculations using the geometry of my Extralite hub... I am not sure which method would be the most accurate? Maybe I should do both and compare the results...

Also should I get slightly shorter spokes to compensate for tension stretching with CX-Ray spokes?

Thanks!

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ergott
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by ergott

I would calculate both ways and compare.

Here's another method. If you have the hub you plan on using built up to a rim with a known ERD you can put that ERD into the calc and adjust the spoke crossing until you get the correct spoke length the wheel came with. Then change the ERD to the rim you want to use. That should be the best way.

Enve uses the same Pillar nipples that Reynolds uses. They are a little longer than the usual Pillar nipples that have the nyloc on the end. The other difference is the threads don't start right away. There is a small indent in the nipple before the threads start which makes building a little easier.

-Eric

kresyzig
Posts: 222
Joined: Sat Apr 16, 2011 8:49 pm
Location: Ottawa, ON, Canada

by kresyzig

ergott wrote:I would calculate both ways and compare.

Here's another method. If you have the hub you plan on using built up to a rim with a known ERD you can put that ERD into the calc and adjust the spoke crossing until you get the correct spoke length the wheel came with. Then change the ERD to the rim you want to use. That should be the best way.

Enve uses the same Pillar nipples that Reynolds uses. They are a little longer than the usual Pillar nipples that have the nyloc on the end. The other difference is the threads don't start right away. There is a small indent in the nipple before the threads start which makes building a little easier.

-Eric


Thanks. So are there three different types of Pillar internal nipples then? I see two on this page: http://www.bdopcycling.com/Pillar-Nippl ... ashers.asp

The ones without nyloc have a little indent, but not on the side you are mentioning, right?

P.S. I asked a question regarding the details of length calculation for straight pull spokes and internal nipples on the wheelbuilding thread...

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ergott
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by ergott

It's the 9.4mm nipple they show. The indent is on the side that faces the hub.

-Eric

kresyzig
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Joined: Sat Apr 16, 2011 8:49 pm
Location: Ottawa, ON, Canada

by kresyzig

ergott wrote:It's the 9.4mm nipple they show. The indent is on the side that faces the hub.

-Eric


Hmm... So the hexagonal end has to face the hub? If I have had to guess I would have been almost sure the round part had to face the hub so it would not scratch the carbon when tensioning it and also to help it to sit at an angle if necessary? Do you know what is the reasoning behind the design of the outer geometry? Is it to help aligning the box with the nipple? Also, why does Pillar call them 10mm nipples? Is it because it is preferable to use 10mm to calculate the ERD although they are 9.4mm? I guess depending of the number of threads on a nipple it can affect the height to use in the ERD calculation, which can be quite different from the total nipple height, right?

Thanks!

kresyzig
Posts: 222
Joined: Sat Apr 16, 2011 8:49 pm
Location: Ottawa, ON, Canada

by kresyzig

ok, so when looking at the actual nipples rather than pictures, it is obvious that the round end should face away from the hub. The edges of the round end are really sharp and it is a no no with a carbon fiber rim...

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