[don qvixote]

Hello!

I'm planning to order the DT Swiss Competition 2.0/1.8 but cannot figure out the size: 288 / 290 / 292 / 294 / 296 / 298 ?

I'm so confused trying to use either the dtswiss spoke calculator or the spocalc.
I get different values in either !!!

I'm trying to build a 700 x 28 wheel (32 holes) to convert my XC to an urban bike.

Can you please help me out in finding the right size of spokes, if I supply some info and values about the parts I'll be using?

(The weight and the dimensions are from the Shimano's tech documents.)

Rim: Mavic Open Pro (Black)

ERD (Effective Rim Diameter): 605 mm (spocalc) / 604 mm (dtswiss calculator)
Weight: 435 g (dtswiss calculator)​

Front hub: Shimano Deore XT HB-M756

Weight: 244 g
Flange diameter: 61 mm
Over lock nut dimension: 100 mm
Center to flange (left): 35,8 mm
Center to flange (right): 35,8 mm​

Rear hub: Shimano Deore XT FH-M756

Weight: 435 g
Flange diameter: 61 mm
Over lock nut dimension: 135 mm
Center to flange (left): 32,15 mm
Center to flange (right): 18,55 mm​

Total number of spokes: 32
3-cross

Thanks for any help in advance.

 

[Mike T.]

And what happens if the info you're given isn't right? Nobody takes back used spokes and they will be used when you're 9/10ths finished and find out they're not right. You must measure the parts yourself (others' info can be wrong there too!) and find a calculator you trust. Try Roger Musson's Wheelpro Spoke Calculator. He wrote it, he shows you how to measure your parts so that the numbers work with his calculator. Order his e-book while you're at it and get the full monty.

That's it.

 

[JD1]

plug all that information into this:

http://www.bikeschool.com/tools/spoke-length-calculator

 

[wmodavis]

+1 on Roger Musson's book! I keep a permanent shortcut to his e-book on the desktop so it's easily accessible.

 

[James Lee]

FWIW, I have had good results with spocalc. I've built at least 4 sets of wheels and not had a problem with spoke calc. If you use spocalc, make sure you are looking at the right number of spoke crossings or input the correct number you want. It is not a big deal to be off by 1mm or 2 from the ideal length.

Look at a number of internet sellers for ERD and hub dimensions, see if there is some general agreement on the dimensions of your parts. Universal, Bikeman, Pricepoint, Webcyclery and Jenson often supply the dimensions important to wheelbuilding.

ERD is the hardest dimension to measure, hub dimensions can be done pretty easily with any caliper. Mavic open pro is one of the most common rims. The range of spoke lengths you are getting for same rims and hubs that have same size flanges is a sign that something is wrong. I trust spocalc as long as the various dimensions you input are good.

If you want to be sure, you could always order your spokes at your local bike shop and tell them what rims and hubs you are using. Let them figure it out. Bring the parts in case they want to measure. Then it is up to them to figure out the length and make sure it is right.

 

[don qvixote]

Thank you Mike T., JD1, wmodavis and James Lee, for your concern and the information.
(I've been away from the computer for 2 days and just find time to read the posts.)

Checking and comparing the calculations in spocalc and bikeschool.com's calculator I see that the sizes are close and as James Lee said, it's really not a big deal to be off (or on) 1mm or 2 from the ideal length.

And I added the Musson's book in my "favorites", in case I'll need it some time.

Thanks once again!

 

[Mike T.]

it's really not a big deal to be off (or on) 1mm or 2 from the ideal length

It's the accepted norm to be within +/-1mm from the un-rounded original calculator number. Let's use the number 275.2 for instance. Go up to 276 rather than down to 274. Not many places stock odd length spokes.