20 spoke hub + 40 spoke rim = viable wheel?

[swee'pea99]

Got a bike recently with a good wheel with a knackered hub. Looking at a good wheel with a knackered rim. Only thing is, the hub's 20 spoke, the rim's 40 spoke. Can I make a viable wheel by simply lacing up alternate holes? (I have a feeling I know the answer to this but thought it was worth asking.)

 

[Landslide]

I don't see why not, as long as the spoke holes on the rim are not offset. The spacing of the holes on the rim should be the same...

 

[tyred]

I think you'll find Sheldon Brown had a wheel on one of his own bikes with a wheel built like this.

 

[brodie]

Depends on the rim I think. Maybe OK if it's a relatively heavy and sturdy deep section rim, but I think a lightweight shallow box section rim wouldn't be a good idea as it would be less rigid. Fewer spokes means each spoke has to be at a higher tension and a low spoke count wheel needs a more rigid rim.

 

[Amanda P]

Moulton restoration freaks are always doing this because it can be really hard to get Sturmey Archer hub shells and rims with matching numbers of holes in the funny sizes they need.

Having the rim with exactly double the number of holes the hub has should make it quite straightforward. Not sure I'd count on the wheel too far off the beaten track though. (It's quite hard to build a flimsy 16 or 17" wheel - small wheels are inherently stronger, apparently).

 

[hubgearfreak]

i'd imagine that it's OK in theory, but in practice, a 40 hole rim, will be, i'm guessing a full size one, 622/630mm. it's possibly also quite light due to it being designed for many spokes. 20 hole full size rims will be a bit more rigid to make up for the lack of spokes. but what have you got to lose? the price of 20 spokes? give it a go and report back

 

[andrew_s]

You might like to consider sealing the unused holes so the rim doesn't fill with water when you ride through a puddle.

 

[jimboalee]

40 hole rims are usually reserved for tandem rears. They have to support 1.2 people.
They are usually thicker wall than 36 hole rims which have to support 0.6 of a person.

Your idea is possible if the holes in the rim are all centrally located with no alternate offset.

The 20 spoke hub is a front?

 

[swee'pea99]

Ended up not getting it - it was part of a deal, and the other parts turned out to be not what I wanted, so it all fell thru' - but thanks anyway.