32" rim on 90mm hub for road?

Bad idea?

Quick math here,
762.5mm ERD for a 36er
~660mm (-4in) for a 32…er?
hub flange width for a 100mm is 68mm
hub flange width for a 90mm is 58? assuming here.

tan^-1(68/762.5) = 5.0962
tan^-1(58/660) = 5.02218

I would say you’re OK. The higher the number here, the stronger the wheel will be. It’s fuzzy math, but at first glance I’d say it will be fine. It will be a similar stiffness as a KH 36er.

I would check the ERD of the actual rim to make sure it’s close to 660mm. Keep in mind that current 32mm rims are single walled, and not nearly as strong or stiff as a Stealth 2 36er rim, so that “similar stiffness” statement above was a lie. It will only be a similar (not exactly the same) stiffness if everything were equal. and stiffness is relative to the wheel size too I believe. In short, I’m not a wheel builder, so don’t trust what I have to say.

I think it would be fine. I have the 32" Kent wheel, and it’s pretty stiff. I ride it with a Schlumpf hub, so the geometry is different, but I think the setup you suggest would be good. Just my opinion.

First I am going to say: From a strength perspective you should be fine with a 32" wheel built on a 90mm hub. In fact it should be about equivalent to using a 125mm disk hub for lateral stability.

Now that that is out of the way I am curious why you would want to? I like slightly off-colour projects but staying within established standards make things easier and cheaper.

I’ve discovered I like narrowness for road.

Thanks to all for the answers.

I use the Nimbus Eclipse (92mm) hub laced to a 700c Mavic Open Pro rim, which I find excellent. It’s lighter than the 100mm Nimbus Equinox hub, and still fits in a 100mm frame if there is a bit of flex (I can get it in my 29" Triton).

It’s such a great set up I’m building another one with a slighter wider road rim.

This is the 92mm hub in a custom frame: