# Bicycle Mechanics - Help Calculateing Spoke Length

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View Full Version : Help Calculateing Spoke Length

Everest
08-18-06, 11:46 AM
The search function doesn't seem to be working, so I'm sorry if this has already been covered. I have specs for the hubs and rims but the info I was supplied dosent seem to match up with what the spoke calculator I tried to use required. I tried this spoke calculator:

http://www.geocities.com/d_halem/wheel/wheel.html

Can someone help me with this. I have a Cannondale Competition front hub (that I want to lace radially) with the following specs:

35mm Flange Width

38mm Flange Diameter

A Ritchey Pro rear (want 3 cross) with the following specs:

`(Drive(19mm))`(Non-Drive(28mm))`(Flange Diameter (45mm))

And Mavic GL330 rims with an effective rim diameter of 615

Thanks for any help.

moxfyre
08-18-06, 11:55 AM
I think you may have a mistake in the terminology you're using: I'm pretty sure that what you mean by "35mm Flange Width" is actually the center-to-flange width. (That's the axial distance from the center of the hub to the left or right flange.) So you should put that in for "Lt. Center to Flange" and "Rt. Center to Flange".

Also, how many spokes on each wheel??? That makes a difference for the rear wheel since it's 3-cross.

Make sure that you have the correct specs and know what each one refers to. Also, here's a Spoke Length Calculator that includes specs on many, many hubs and rims, and is a bit more clear to use I think: http://www.damonrinard.com/spocalc.htm

Everest
08-18-06, 12:43 PM
Those are the specs from the seller

moxfyre
08-18-06, 12:49 PM
Those are the specs from the seller
I'm afraid that they're incomplete, then. You can try contacting the seller by phone to get the specs clarified.

You *need* to know the number of spokes for the 3-cross rear wheel, because that affects the spoke length.

Also, you need to figure out what "Flange Width" means. I presume that it does NOT mean "Flange Diameter", since there is another spec labeled "Flange Diameter". My best guess is that "35mm Flange Width" means that the center-to-flange distance is 35 mm, since 70 mm is a very reasonable width for the front hub.

As for the rear hub, "Drive 19mm" means that the center-to-right-flange distance is 19mm, and "Non-drive 28mm" means that the center-to-left-flange distance is 28 mm.

What do you get when you put those numbers in?

Everest
08-18-06, 12:54 PM

Everest
08-18-06, 12:57 PM

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=007&item=170017782395&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&ih=007&item=170017573456&rd=1&sspagename=STRK%3AMEWN%3AIT&rd=1

Everest
08-18-06, 12:58 PM
They are 28 hole and for the rear I get: Left=303.4 Right=302.7

Everest
08-18-06, 01:08 PM
I measured the front hub with calipers and get about 65mm to the inside of the flanges and about 73mm to the outside flanges.

moxfyre
08-18-06, 01:16 PM
I measured the front hub with calipers and get about 65mm to the inside of the flanges and about 73mm to the outside flanges.
Okay, so use the 73 mm number for the outside of the flanges. Since a front hub is symmetric, that'll be 35 mm on either side.

For the rear hub, I calculate 302.6 and 303.3 mm spokes, same as what you got :). Round up and buy 304 mm spokes (it's best to err on the side of slightly too long).

For the front hub, I get 289.4 mm spokes (using 38 mm flange diameter, 69 mm width, 38 mm flange diameter, and zero-cross). So get 290 mm spoke for the front wheel.

Hope that helps!