DT spoke length cal...
 

[Closed] DT spoke length calculator help!

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I have:
Hope XC hub on an XC717 disc rim
XT 6-bolt hub on an XM719 disc rim

I want to rebuild the Hope XC hub onto the XM719 disc rim as it seems to ride better with bigger tyres (being wider) and get the use the slightly quicker engaging Hope XC

I'm stuck on working out how longer spokes I need as the different rim profiles mean the existing spokes might not work with the original spokes?

Anyhow, what goes in these boxes?:

No. of intersections le. ___ ri. ___


 
Posted : 24/05/2009 2:15 pm
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3 usually.


 
Posted : 24/05/2009 2:20 pm
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the ammount of crosses the spokes do with each other. as it has been said it is normaly 3


 
Posted : 24/05/2009 2:30 pm
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Right

Next Question:

The calculator works out to the nearest mm of spoke length

Having a quick search I've found spokes in 2mm (even) increments

When the calculator specifies an odd mm length, do I have to use one of this length? How much leaway is there each way to use a 1mm longer spoke or a 1mm shorter one?

If for eg:
Spoke length comes out as 261.5mm, rounds to 261mm
Can I use a 262mm or will it poke into the rim tape?
Can I use a 260mm or will there be too few nipple threads to take the tension?

Not just for that eg, but how much leaway should I have either way?


 
Posted : 24/05/2009 2:34 pm
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You will be fine with either and tbh I have never found the DT calculator accurate to within 1/2mm in practice anyway.


 
Posted : 24/05/2009 2:36 pm
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Sorry, yet another question:

When it comes up with the precise and rounded spoke lenghts, I presume the le. is length and ri. rise? Whats the difference? Is this something that will/would become apparant when reading through wheelbuild guides (such as sheldon brown - does park tool have one as well?)


 
Posted : 24/05/2009 3:01 pm
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2mm + or - the exact length is usually fine.

Careful of your nipples though


 
Posted : 24/05/2009 3:02 pm
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le and ri are left and right. If you use DT spokes then, apart from the 257mm in black(which you may not need anyway), all the sizes are available in 1mm increments in the range to suit your build.


 
Posted : 24/05/2009 4:31 pm
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le. => left (non-drive side)
ri => right (drive side)

Both are lengths. (Damn, coatsey beat me to it :D)


 
Posted : 24/05/2009 4:32 pm
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"all the sizes are available in 1mm increments in the range to suit your build"

I had a quick look on CRC who only stock every 2mm (in even # lengths)
I'll look a bit harder

Am feeling quite stupid now for not seeing le. and ri. as left and right now ..


 
Posted : 24/05/2009 5:26 pm
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CRC aren't the only place that sell spokes(but they are cheap though), try your LBS if you want to do the job properly, even my local Bike Hut at Halfords used to keep a stock.


 
Posted : 24/05/2009 6:12 pm
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Be aware thast CRC may send you 14mm nipples not the standard 12.

They have on the last 2 sets I've had anyway.


 
Posted : 24/05/2009 7:51 pm
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Other than wieght, what problems will a 14mm nipple cause over a 12mm one? Not enough thread on the spoke?

CRC was just a quick look to guage whats available and roughly how much they cost


 
Posted : 24/05/2009 7:53 pm
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Unless the nipple will keep on screwing down the spoke, past the threaded section (it won't on DT comps),then you'll need shorter spokes with a longer nipple otherwise it may bottom out before it's tight.


 
Posted : 24/05/2009 10:53 pm
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Double check the ERD on that 719 Rim from whats given on the DT Calc as ive built a few of these recently and have needed to go 4mm longer (or use 16mm nipples) each time.


 
Posted : 24/05/2009 11:04 pm
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Just checked and DT List it as 532mm. Im pretty sure its actually 539mm.

As a roughish rule 0.5mm diff in ERD equates to 0.3mm in spoke length.

7mm diff in ERD therefore a 4.2mm longer spoke (or nipple) which is pretty much what i found.


 
Posted : 24/05/2009 11:12 pm