I just discovered a crack in the back rim of my mother's bike and I'd like to replace it. The trouble is that the hub is 40 spoke and I cannot find a 40 hole rim that would fit the bike and would be less expensive than buying a new bike.

However I can find plenty of 36 hole rims that are perfect (other than the fact they have 36 holes).

I was wondering if there are lacings that are safe for connecting a 40 hole gear hub to a 36 hole rim.

I would rather not replace the entire wheel because it would, due to the rather antique internal hub currently in use, likely mean adding a derailleur, replacing the gear-line and replacing the chain, which just seems a little overkill.

  • Is the dead rim steel or aluminium? If its steel, I'd just buy a new aluminium rim for both wheels. Yes they cost more, but aluminium rims are such an upgrade over steel rims.
    – Criggie
    Oct 5, 2019 at 2:53
  • I don't know what kind of vintage hub your bike is using, but you can get used internal gear hubs quite cheap. Just ask your local bike shop whether they have a used 7 gear SRAM for your purposes, for instance. I payed only 25 Euros for my last hub that way. Those SRAM hubs are not built anymore, but they are quite robust and serve you excellently in the city. Oct 5, 2019 at 5:42
  • So what happened in the end? Did you move the rims around and rebuild both wheels ? How did it work out for you, and is your Mum happy ?
    – Criggie
    Sep 23, 2020 at 2:30

1 Answer 1


"Perverse" is what Sheldon Brown calls this sort of wheelbuilding, but it apparently can be done. There are even video tutorials for a 32-36 mismatch, which might help you. Unless you really need a sturdy rim, you could look into using a 32-hole rim as a 4:5 pattern might be simpler than 9:10. You need several sizes of spoke for such a build.

Another option worth a look is trying to get undrilled rims, though they're probably expensive.

I have heard of people building wheels ignoring the spoke hole offset from the centreline, or filing out the holes if the offset is slight. Doing that on a 20-hole rim would mean you'd have to drill every other hole - but be careful as the valve hole could easily be a problem (most but not all of my wheels have it halfway between spokes). I'd be wary of such an approach personally.

I don't suppose the front is 40h is it? Building a new front wheel and putting the old front rim on the back would be a neat solution if it is, but 40h front wheels aren't common.

  • 2
    A quick check of UK and US sites suggests that 40h rims can be had for under £/$30, though most are twice that.
    – Chris H
    Oct 4, 2019 at 19:10
  • 5
    The front rim is 40 holes! That is a clever solution I had not thought of, although I don't know if I will end up using it. Oct 4, 2019 at 19:32
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    The downside of using the front rim is that you end up building two wheels (unless you just buy a cheap 32h/36h front wheel) but they're normal builds. I'm a novice wheel builder and would much rather build two normal wheels than one tricky one
    – Chris H
    Oct 4, 2019 at 20:25
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    Brilliant thought on reusing the front rim, but then OP is left with a front 40 hole hub and no suitable rim, so it means buying a complete new front wheel. Second thought is to check for brake track wear on the front rim, which may render it unsuitable.
    – Criggie
    Oct 5, 2019 at 2:52
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    @Criggie indeed, but a routine front wheel is cheaper than a geared hub, even new, and there's more chance of picking up a second hand wheel. Good point about brake track wear, but hopefully the front hasn't suffered too much.
    – Chris H
    Oct 5, 2019 at 6:30

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