But you can use mountain bike hubs for building a new road bike or swapping hubs with a road bike but in one case, if the hub is compatible with the road bike wheels, there are many non-compatible things that differ between mountain bike hubs with road bikes. the inner bearings are almost the same and do not cause any big issue in swapping mountain bike hubs with road bike hubs, their numbers are also the same, the main thing which is important, you have to look for the spokes, count them on the road bike wheels, and then count the flange holes on MTB hub, if both are equal then road bike wheels and mountain bike hubs are compatible with each other.
The inner width and diameter of the MTB match should match equally with the previous road bike hub which you removed and you are swapping with a mountain bike hub because the previous road bike hub was compatible with the QR skewer and thru axle of your front and rear wheelsets, and the diameter and width of new MTB hub on a road is important o match with the QR skewer and thru axles of your road bike wheels. without this, you have to make the bushings and clamp holes of the QR skewers and thru-axles of the frame and front forks compatible for inserting a new mountain bike hub on a road bike, if all of these things are matching with a new MTB hub on your road bike, then it is easier to swap or change road bike hub with a new MTB hub.
MTB Hubs are mostly used for commuting and touring purposes, because these hubs have greater durability and these would run smoothly on road and gravel bikes, it s the main reason these are basically installed on other commuting bikes also.
It is important to check the spacings of the right and left side of the hub when you are inserting it on a road bike, a few examples are given below:
142 mm boost hub with 12mm length is not compatible with the 135mm hub spacing road bike frames, MTB hubs are larger in length and diameter as compared to the road bikes, all the new modern and expensive road bike frames have 13omm to 131mm frames and hub spacings but MTB hubs are wider and thicker than these diameters, these spacings would matter a lot for inserting MTB hubs on a road bike.
Mountain bike hubs are thicker with a greater diameter and road bike hubs are thinner and narrower.
Dis Brake Issues For New Hub:
All the disc brake brands include Magura, VID, and Hayes, these are mostly non-compatible with the new hubs, it is because these would cause many issues, problems, and difficulties with the new hubs, but Shimano brakes are easily swappable and compatible with the new hubs if your road bike have Shimano brakes installed in front and rear wheels then, new MTB hub would not cause any issue in swapping and changing.
Length Of QR Skewers And Thru Axles:
If the length of QR skewer and thru axles is greater or smaller than the new MTB hub then it is also a major problem because greater length QR and thru axles need cutting, and shorter or smaller length of QR skewer and thru axles need new threadings for making them compatible with the new hub.
Chain Line Stay:
The Mountain bike hubs on a road bike mostly cause the problem of chain dropping and distracting from the actual line between the rear cassette and the front crankset. it occurs due to the tightening and loosening of the QR skewers, thru-axles, and swapping of new MTB hubs on new wheelsets, you have to maintain chain line by wheel builder sand mechanic shops and if the issue is small and negligible, do it yourself.
Weight does not matter in swapping and changing mountain bike hun on road bike wheels, 20g to 30g is a negligible and small amount of difference in weight, although more amount of MTB hubs are more durable with greater strength.
Is It Possible To Stretch Mountain Bike Hub OPr Road Bike Frame?
Stretching of hub and frames depends on the material of the hub and frame, aluminum and carbon frames are not stretched but if mountain bike hub and road bike frame are made up of steel metal, then steel can be easily stretched and you can easily change the length of the hub and spacing of the front and rear bushings of road bike frames.
Longer and shorter hubs( QR skewer and thru axles) can also be made compatible by inserting the spacers on the drive side of the rear wheels, spacers are mostly used for the longer hubs and longer QR skewers of the mountain bike hubs.
These spacers would correct the chain line and prevent the chain from dropping and also make road bike cassettes compatible with the mountain bike hubs.
Boost, Non-Boost, And Superboost Hub Spacings:
All of these hub spacings totally depend on the width and diameter of the hub, if these are compatible with the QR skewer and thru axles of a road bike and the road bike frame is compatible with disc brakes then yes it is possible to install these hub spacings on a road bike, but on a normal basis Boost hubs are modern and new discovery in the mountain biking world, there is a big difference between boosted and non-boosted mountain bike hubs, boosted hubs are wider and thicker as compared to non-boosted basis, on a normal basis, boosted hubs are not installed and are non-compatible for road biking, but unboosted hubs are older hubs with the thinner diameter and these are compatible with the road bike thru-axles and QR skewers and also compatible with road bike frames and disc brakes.
Superboost hubs are much thicker in diameter than boost and un-boost and boost mountain bike hubs, it shows that super boost mountain bike hubs are also non-compatible with the road bike frames.
Difference Between Thru axles And QR skewers:
Thru axles are an older discovery for mountain bike wheelsets and hubs but QR skewers are a new modern discovery for mountain biking, there is also a difference between them, the thru-axle is covered by ends caps on both of their ends by threading which needs unscrewing with tools in the case when the tire got punctured or you want to install wheel from the frame, but QR skewers do not contain ends caps or bolt nuts for mounting and unmounting of wheelsets of mountain biking, based on this difference if mountain bike hub is compatible with the thru-axle and new road bike frame wheelsets are mounted and unmounted by thru-axles, then these hubs would not work with the QR skewers of road bike frame, due to the compatibility issues, and if mountain bike hubs are compatible with QR skewers, while road bike wheel and the frame contain thru-axles for mounting and unmounting of tires the setup becomes non-compatible and won’t work.
Mountain bike thru axles hubs would work on road bike thru axles wheels and mountain bike QR skewer hubs are compatible with the road bike QR skewer wheelsets.