[MikeD]

Man, I've been having a hell of a time getting the right spoke lengths for a Hope Bulb front/sport rear to Mavic 521 36h build (and a Bulb f/r to 519 32h build I'll be doing soon...)

Used the DT spoke calc, bought all the spokes locally, as the shop had almost every size I needed in DT 14/15/14...then turned out some of the spokes were too long. Figured I'd done something wrong, ended up trying to exchange them all and finding out they didn't have the sizes I wanted, drove all over trying to find them, finally returned it all then ordered just the right lengths from Nashbar. Finally got all the pretty new spokes in their own packages and eagerly awaited a chance to put the wheel together.

Then, last night, after unlacing the too-long spokes and relacing, I found that the 257/259mm lengths the spoke calc had quoted me were STILL far too long! Checked the Hope calculator at Hopetech.com, and it's giving me 254 and 258mm lengths!!! That seems a lot more realistic, given the way the wheel looks now.

Grrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr, DT Swiss, I wanna kill ya. Anyone else found inaccuracies in their database?? The rim ERD is 1mm different, but the hub info in both seems WAAAY off.

Guess being a hack wheelbuilder has its disadvantages. Time to spend yet MORE money on mail returns and ordering.

 

[SKYWAYBUZZ]

What works for me is to take the hub and rim into my LBS and let him measure everything and calculate some numbers to get my lenght. He will then cut them spokes on a machine that also threads the end of the spoke, because I've never been able to use spoke calculations.

 

[sub6]

that's a bummer, the hub data must be WAY off. A change of 1mm at the hub flange translates to 0.1mm of spoke length. In other words, the flange diameter can be off by 10-15mm and that won't cause a problem with your spokes.

I don't believe I've ever been led astray by DT's calc, but I frequently use the manual data-input instead of just choosing a hub or rim from the menu....

 

[Rev.Chuck]

I use the old school DT swiss calculator. It is a rim measure stick, calipers and a simple chart to perform the calculations. I have used it to build around 90 to 100 wheels in the last two years and it has not failed me yet. As a side note if you rebuild a used hub use spoke washers, they really improve the evenness of the tensioning.

 

[MikeD]

Spoke washers??? My lord. I had no idea. I learned all my skills (meager as they are) from a book, and I'm seeking to actually be good at it someday. The ones I've built have held up to hardtail freeride abuse, so I must be doing it at least passably...it doesn't seem like rocket science at its most basic level...but there are all these little tricks to learn.

I keep entering the data in the calculators, thinking I must have been wrong somewhere, but it's gotta be them.

The data's off with the 519s, too, so I suppose their hub dimensions are pretty far off.

How should I round spoke lengths, by the way, and how many mm off can a spoke be before it's not usable?

MD

 

[Rev.Chuck]

One more thing, use a spoke ruler to check that the spokes are the claimed length. Sometimes the shopguys(mine anyway) have a little trouble putting them back in the right spot. I pulled a twofiftysix out of a open bag of 297's (and the five key does not work,darn Gateway laptop)

 

[sub6]

Originally posted by MikeD


How should I round spoke lengths, by the way, and how many mm off can a spoke be before it's not usable?

MD

I'd say 2mm off is the limit. Ideally you want to be within 1mm but I'd be willing to do 'em if they were off by 2mm.

Round to the nearest whole number.

Originally posted by sub6

A change of 1mm at the hub flange translates to 0.1mm of spoke length. In other words, the flange diameter can be off by 10-15mm and that won't cause a problem with your spokes.

This applies to 3x wheels ONLY, I forgot to mention. The effect would be even less notable on a 4x, and by the time you get to radial lacing, 1mm = 1mm.

 

[Rev.Chuck]

I just typed this once and realized I was in under my wifes name
Building a wheel is not hard, the hard part is getting to the point of doing it quickly without making any(mostly) mistakes.
Get a DT wall chart calculator, it is not expensive and has never failed me, plus you can swat people with the rim stick, it stings.
If you use the Dt online calc I think you can enter the hub dimensions but figuring flange offset requires a little work. Find the center of the hub from the axle nuts and from there to each flange.
I prefer to round up. It is better to have a little spoke sticking out of the nipple than to not have full engagement. Esp. since that little flared bit on the nipple is holding it to the rim. In the old days, when there were fewer box section rims the goal was to not quite have the spoke stick out because it was hard on the tubes.
It can protrude a little, maybe two mil max. You want to keep full thread engagement. If, when the wheel is fully tensioned the spoke end is just inside the nipple, level with the slot, that is OK.

 

[pugslybell]

I have built over 100 wheels, and for free ride/dh wheels which you will flat spot i prefer to go shorter on the rounding. As mentioned before for three cross 2mm difference is acceptable but nothing beats having the proper length. A really good way to figure out spoke off set is to measue out the over locknut dimension, usually 135 mm for rear mountain hubs on a piece of paper with a staight edge. then make a mark on it at the mid point (67.5mm for those that dont like math). Eyeball the hub so that the locknuts(part that touches inside of dropout) are ate either end of your straight line. Make two marks at the point the hub flanges intersect your line and you now have your center to flange measurment. Hope this helps you get the right number. This method works for all hubs including rear hubs with floating brakes, the measuring just gets more fun.
Have a good day and good luck building your new wheels

 

[Matt D]

Originally posted by SKYWAYBUZZ
What works for me is to take the hub and rim into my LBS and let him measure everything and calculate some numbers to get my lenght. He will then cut them spokes on a machine that also threads the end of the spoke, because I've never been able to use spoke calculations.

Damn dude, that is OLD school!

 

[Rev.Chuck]

Ah, yes, the Phil spoke cutter. Now that is a shop tool. Three thousand dollars of handbuilt precision, cuts and rolls in the threads with the turn of the crank. It even has a wooden handle.

 

[MikeD]

Well, despite much wasted time and effort, here they are...

At least I learned some things along the way, and my building technique gets better every time.

Had to go to 2 shops and get them to take measurements...and the spokes are still a bit too long! However, I didn't run out of threads, and they're already at a really high tension (plus, I gradually cranked it up, then backed it off, to try and pre-stress them even more than usual), so I don't forsee any problems. The rim section is so deep...plus, I'll be trying the Maxxis tubeless system with them.

I also settled for 14g vice 14/15/14 just because that's what they had in stock...and it was half the price. Don't think I'm missing much, especially on a set of freeride HT wheels.

(Hope hubs to 521s, by the way. Rear is a ceramic for some odd reason; got it cheap, but I'll be using discs, so it's kind of a waste).

Thanks for the help, encouragement, and sagely advice.

MD

 

[MisterMental]

just a thought: DT might not have updated their calc. and its got teh stats for the old hope bulbs [the ones with teh sider] before the ISO 2000 came about?

 

[MikeD]

Nah, they have both types listed...I was wondering about that myself...

But has DT changed the way it measures its spokes to bring them in line with other manufacturers? I was told a few years ago they ran a bit short, but someone told me that had changed the other day...

MD

 

[MisterMental]

maybe. it might give lengths for use with THEIR nipples?