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I'm renovating a folding bike with 20 inch wheels and want to replace the wheels.

Will BMX wheels fit ?

EDIT 22-Feb-2020: 10mm BMX wheels dropped straight in with no mods.

The BMX freewheel was threaded on, I just screwed it off and screwed on the shimano six-speed cluster from my old bike. It needed extra spacers on both sides of the rear axle beyond what came with the BMX wheels: I used the ones from my old wheels so I didn't have far to look.

The only thing that shows that they are not made-to-fit is, on the front wheel, the ends of the axles stick out half an inch or so beyond the wheel nuts. I suppose I will cut them off in time.

I get it that I will probably have to go single-speed and therefore also replace the crank and chain. Is there any other reason they are not compatible, like different dropouts or axle width... I also know that a 2-inch BMX tire will fit in this frame, I fitted one once.

This is the bike I want to fit BMX wheels to

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    You should add more specs of the current wheel. Axle size etc, otherwise the only valid answer is 'it depends' :) Bmx wheels come in different axle sizes (3/8" and 10 mm diameter and possibly others) and different hub spacings as well, common is (if I'm not mistaken) 100mm front and 110mm rear. And then there's also the choice of male and female axles. So in essence you'll have to measure it exactly then start looking for a match. Also consider non-bmx wheels perhaps, they might be cheaper. And less strong, but you don't need that kind of wheels on a bike like this anyway.
    – stijn
    Commented Nov 30, 2019 at 16:50
  • Do you have the ETRTO size numbers for the wheels? If both tyres have the same 3 digit number then that's really positive. Its probably xx-451 or 451-xx, but some other 20" sizes exist too.
    – Criggie ♦
    Commented Nov 30, 2019 at 22:59

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Thanks, guys, like you say "it depends". But those pointers allowed we to find the answer for my own case which is:

"Yes, if I get 3/8 inch BMX axles and bend (cold set) the rear frame or add spacers."

Axle Diameter

Cheap store-bought bikes like mine have 3/8" or sometimes 10mm axles, which are practically the same. BMX ones are either 3/8", or are 14mm, which is a good bit larger.

It's not quite game-over for the 14mm BMX axles though because some have flats on them so they fit 3/8 dropouts as well. If the axles are solid you can file the flats yourself - but a lot are not.

Opinion was pretty unanimous - do NOT file-out the dropouts to take he larger axle.

Front Wheel

The width of the road and the BMX axles are both generally 100mm so the 3/8" BMX front wheel often drops straight in.

Rear Wheel

The rear axle is significantly wider on a road bike - 130mm on the road vs 110mm on a BMX. The BMX axles might be over-length enough to fit if you put in a 10mm spacer each side. Or you can bend-in the rear frame if it is steel to take the narrower axle (cold setting).

Just want to reinforce that the full answer is indeed "it depends", and this answer is specific to for cheap store-bought bikes with steel frames.

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  • Good answer to your own question! There may be one more thing worth considering, namely the new BMX wheels' braking surfaces being compatible with your present V-brakes. Just make sure the new wheels have machined surfaces wide enough.
    – Grigory Rechistov
    Commented Nov 30, 2019 at 22:15
  • And what about the gears? BMX generally don't use derailleurs.
    – Carel
    Commented Dec 1, 2019 at 15:26
  • Great answer, exacly for what I looking. I need change wheels on my folder to allow carry higher load - e.g. need stronger wheels & hubs...
    – clt60
    Commented Mar 12, 2021 at 17:46
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You are correct that different bikes have different spacings between the dropouts (and hence different how widths and axle lengths). Measure the inner distance between the front and rear dropouts and compare with the specs of wheels you want to get. Beware that sometimes frames and forks spring in or out a bit when the wheel is taken out.

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Here are the wheels fitted. Now, I can get on with renovating the rest of it.
Wheels fitted

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