Wheel building?

[Bentley]

I hope this is not too stupid a question. I have a pair of 40 spoke aluminum rims that I would like to build using 36 spoke hubs. Can this be done by leaving 4 spokes out at 90 degree angles of each other? Will it true right? Thanks.

 

[mjw_byrne]

In theory you ought to be able to get it true, and roundness shouldn't be too much of an issue, but you might find that you need more than one spoke length to make up for the fact that the holes in the hub are differently spaced to those in the rim. It should be an interesting-looking wheel!

 

[daveornee]

Originally posted by Bentley
I hope this is not too stupid a question. I have a pair of 40 spoke aluminum rims that I would like to build using 36 spoke hubs. Can this be done by leaving 4 spokes out at 90 degree angles of each other? Will it true right? Thanks.

Yes, it can be done, but before you start recognize that it will be sub-optimal due to the unsupported sections of the rim, balancing tension and getting best available true.
Spoke length calcualtions are more complex as well.
The wheels will be slightly weaker and less durable than 36 spoke wheels built on comparable 36 hole rims.
Have you thought about trying to swap/sell either the rims or the hubs to get a "matched" set?
Rec.bicycles.marketplace is one place to try.
40 hole hubs and rims are very unusual now a days, but someone may be in the position oposite yours; having 40 hole hubs or 36 hole rims they want to trade.

 

[Bentley]

Well these are 27" x 1-1/4" rims and there are some 36 hole ones on ebay but they are all I've found. My old steel rims are tough to keep from rusting and I would prefer the lighter aluminum. I have plenty of different sized spokes so that's no problem and have never seen a 40 hole hub anywhere. I know there are brake issues if I convert to 700's but maybe that's the way I'll need to pursue. Thanks for your imput guys.

 

[mikeg]

Originally posted by Bentley
Well these are 27" x 1-1/4" rims and there are some 36 hole ones on ebay but they are all I've found. My old steel rims are tough to keep from rusting and I would prefer the lighter aluminum. I have plenty of different sized spokes so that's no problem and have never seen a 40 hole hub anywhere. I know there are brake issues if I convert to 700's but maybe that's the way I'll need to pursue. Thanks for your imput guys.

Velocity make 36 hole 27" alloy rims for their replacement 27" wheels

40 hole hubs are often used on tandems.

My old 1960's bike has a 40 hole 3 speed Sturmey Archer hub on it!!

Mike