Bicycle Mechanics - Spoke Calculator(s) vs. reality ???

Hi

I´m about to respoke a rear wheel with Campagnolo Veloce Hub and Mavic CXP 22 rim.

The spokes I´ve taken from the wheel (drive side) are 295mm long measured from beginn of thread to the point where the spoke begins to bend.

I tried with the DT Swiss Spoke calculator and it gives me 288/290mm (DS, NDS).
Same values (+/1mm with the calculator of Mavic)

Where the original spokes wrong or what´s the explanation?

Same issue with another wheel with DT Swiss rims, hubs, spoke (R1.1 single, 240, aerolite) made from another shop in anoher country.
I have a spoke I replaced (an aerolite) and this is 291mm.
The DT Swiss calculator gives me 285mm for the same drive side.

What´s up? :eek::eek::eek::eek:

Thanks a lot!

From my experiences wheelbuilding in the shop: the best way to get the length right is if you have an actual spoke from the wheel. Sometimes on new builds, the spokecalc gives me wrong measurements (which usually isn't evident until the wheel is at least half laced). One possible cause of discrepancy in your case could be the lacing pattern.

yeah just go by what you have on there. I used a spoke calc on my rear wheel and they ended up being to long.

How many cross? I've used Spocalc for a few years, and every time I've had the wrong length spoke, it's because I've looked at the wrong number of crosses on the output. Other than that, it's been perfect.

Did you actually measure the rim or just pick the rim off the menu offered by the DT Swiss calculator ?
From my experience the DT swiss calculator menu does not reflect the actual diameter of Mavic rims.

To measure actual diameter cut the elbows off of two spokes such that they are the same length. Thread nipples on such that the end of the spoke is flush with the bottom part of the slot in the nipple (fully engaged but so you can still tighten it more if you have to). Lace them into two rim holes 180 degrees from each other. Measure the gap and add twice the spoke length. Now enter this into the DT Swiss calculator. It's always worked for me.

Mavic does not give their rim diameter in the same measurement of ERD that the spoke calculators use. I have no idea why.

I've never had an issue with Spocalc giving me a wrong length, but I always measure and doublecheck my hub's dimensions vs. their database.

Hi

Lacing is 3x both sides.
As for the ERD should be ok CXP 22 -> 599mm.
I´ve found the same value everywhere.
The Mavic calculator where I entered the rim type gave me almost same values as the DT one, out of 1mm or so.

The campy veloce hub I measured roughly and the given sizes look ok.

Meanwhile I ordered the spokes a little longer that advised by the calculators and a little shorter than the curent ones (ordered on line, I need the wheel soon and little time to browse for shops which would have to order the spoke aso)
It´s not a huge investment (competition spokes) and I hope in the worst case to be able to recycle the spokes intended for the NDS on the DS.

Another funny thing is, the currently used spokes are the same length both sides - I didn´t want to believe it but I measured and compared them more times.
The wheel was built years ago by a VERY experienced builder but some 600km from where I live now.
Either he let a youngster do the job or he was in a hurry ...???

Now let´s see what happens.

Thanks for all contributions, present and future.

Used Jobst Brandt's book (http://www.amazon.com/Bicycle-Wheel-3rd-Jobst-Brandt/dp/0960723668/ref=sr_1_1?ie=UTF8&s=books&qid=1220253253&sr=8-1) to build my wheel. Back then there wasn't any fancy "calculator," it was pencil and paper. Worked first time, never had a single broken spoke, 15 years and counting.

Hi

I´m about to respoke a rear wheel with Campagnolo Veloce Hub and Mavic CXP 22 rim.

The spokes I´ve taken from the wheel (drive side) are 295mm long measured from beginn of thread to the point where the spoke begins to bend.

I tried with the DT Swiss Spoke calculator and it gives me 288/290mm (DS, NDS).
Same values (+/1mm with the calculator of Mavic)

Where the original spokes wrong or what´s the explanation?

Same issue with another wheel with DT Swiss rims, hubs, spoke (R1.1 single, 240, aerolite) made from another shop in anoher country.
I have a spoke I replaced (an aerolite) and this is 291mm.
The DT Swiss calculator gives me 285mm for the same drive side.

What´s up? :eek::eek::eek::eek:

Thanks a lot!

Lately I found an error of mine regarding the DT Swiss wheels, I set 2cross instead of 3cross.
Now with 3cross I get 295/296 (DS/NDS) - which s longer than what I have in the hand...

I have used the SAPIM spoke calculator for many different rims. I always ended up with perfect spoke lenghts.

All distances should be measured and double checked with great care. Then nothing can go wrong. The most difficult part is to measure the rim's diameter, as it may not be a perfect circle in it's non laced condition. Measure the rim at different spots and calculate an average.

Mavic does not give their rim diameter in the same measurement of ERD that the spoke calculators use....


Hi

As for the ERD should be ok CXP 22 -> 599mm.
I´ve found the same value everywhere....

The CXP 22 is not in my version of Spocalc, but from Spocalc "ERD is Mavic's Nipple Seat Dia + 3mm for nipples". Just make sure that value posted everywhere is an ERD, not Mavic's published NSD.

yeah just go by what you have on there. I used a spoke calc on my rear wheel and they ended up being to long.

Just make certain your nipples are the same. Most calculators assume a 12mm nipple. I rebuilt some old MTB wheels from the early 1990s that were built with 16mm nipples. I ordered exactly the same length spokes as previous along with new 12mm nipples. The build was "ok", but many spokes had a thread or two showing when it was all done.

I've never had a problem with the DT Swiss calculator. Always round down fractions to the shorter length so that you don't run out of threads.

Al

As afterthought I ordered the spoke NDS almost the same length as the original ones (just 1mm shorter = 294mm) and 292mm for the DS.
I just have to find the time to pick them from the post office (easier said than done) probably on coming Friday.
Then I´ll let you know - should anyone out there be interested at all.
Something I learnt: measure the rim by yourself! :thumb:

Kind regards from the Alps Republic!

I've never had a problem with the DT Swiss calculator. Always round down fractions to the shorter length so that you don't run out of threads.

Al

I'm having trouble using the DT calculator. How do I measure pitch circle diameter? Flange distance?

I'm trying spocalc but going crazy trying to figure it out. My hub is not listed. It is a track hub with some spacers, so having trouble figuring out some of the measurements with the cone, washer, nut.

My main issue is that I'm reusing my hub, but have switched from Mavic Open Sports to Mavic Open Pros. Not sure if my old spokes are the same length that I'll need...

**Figured everything out via spocalc. Ah, the joys of wheelbuilding:)