It is possible if the distance of the right and left flange hub would match exactly with the distance of the rear dropouts of the frame and the front dropouts of the fork of mountain bike frames. BMX hubs are different from Mtb hubs because these have larger distances between the flange hub holes which differ them in compatibility with the mountain bike frame and hub diameters and axles, and also flange holes of the BMX hubs are greater in number than mountain bike hubs, 48 hub hole BMX hub is not compatible with the of 28, 32 and 36 rim holes.
Mountain bike hub axles are also not compatible with the BMX hub lengths because of the smaller length of the Mtb axles so need spacers on both drive and non-drive sides of the rear wheels and also for front wheels to make BMX hubs compatible with the Mtb frames and axles. but using mountain bike axles with the BMX hubs is not a worthy step because BMX hubs are wider in diameters and the Mtb axles do not support the tolerance of BMX hubs over time and the axles would break or start deforming, so you need new compatible axles for installation and mounting of BMX hubs on a mountain bike.
BMX hub axles have 14mm of lengths which is almost a greater length than Mtb hub and dropouts and these would not stay correctly within the dropouts and keeping of front and rear wheels on Mtb frame. the main difficulty you will face is centering of front ad rear wheelsets of Mtb frame with new BMX hubs. the other compatible method is installing new washers but after installing washers the lining of the chains from the derailer cassettes to the crankset would change, which needs adjusting and accurate maintenance of chain lining.
The actual dropout spacing of the BMX hub is 110mm and the mountain bike dropout spacing is 135mm. it shows that there is a large difference between both of these hubs, both of these hubs would also require different internal axles, spacers, and washers for making the setup compatible with each other. the threading of both of these hubs is different on the drive and non-drive sides, which also cause a big difference when you are going to insert BMX hubs on mountain bike frames and forks.
Difference In BMX Hubs Axles:
BMX axles are not the same as BMX bike frames, these are further divided into two categories.
- Male BMX axles
- Female BMX axles.
And also their sizes are different, BMX hub axles are manufactured in two sizes.
- 3/8, it is a smaller size but mostly the riders would not exactly know about this size of BMX axles, because this size is famous as 10millimter. so we can call 3/8mm size axles 10mm axles.
- And the larger size is 14mm.
10mm or smaller sized axles are mounted and installed in front fork dropouts or front wheels and larger sized 14mm BMX hub axles are used for rear wheelsets. for mountain bike frames and forks 10mm is a little bit compatible by inserting spacers with these smaller-sized axles within the rear and front wheelsets. but 14mm is a larger size, you have to buy a new frame and fork for this conversion.
Female Hub Axles:
These are different from male axles and these are threaded on both drive and non-drive sides, their characteristics and properties are matched with the freewheel hubs threaded on both sides.
Male Hub Axles:
These are not threaded on both sides, these contain internal hollow space, and the threads are made internally, nut bolts and end caps are also threaded internally and these look clean from the outside. the look and aesthetics of these male axles are different from all the other categories of axles in biking which include road biking, mountain biking, and gravel biking.
Major Difference:
The main difference between both of these hubs is that they are meant for different working purposes, BMX bikes are used for whipping and performing stunts and the hubs of these bikes are without gears, which we can call as these are single wheel hubs, but mountain bike hubs are made for higher speed purposes, and also Mtb hubs contain gears on the drive side, these are the major differences which make both of these hubs non-compatible with each other.
Frame Difference:
Frames of BMX and mountain are not compatible with each other and there is a big difference between the material of both of these bikes and also in price ranges, mountain bike frames are usually manufactured in two materials which are carbon and aluminum but BMX bike frames are manufactured in steel and Cromo.
Based on this difference mountain bike frames are not manufactured in Hi-ten steel and CroMo materials and BMX frames are not manufactured in carbon and aluminum, this difference would make the dropouts and forks of both of the bike frames non-compatible with each other for swapping and interchanging of hubs and axles.