Yes, it is possible to convert hardtail into full suspension but hardtail and full suspension are two different mountain bikes, and converting hardtail into full suspension means converting one bike into another, which surely needs to replace bike parts which need spending a lot of bucks to make bike parts compatible with both of these bikes. hardtail bikes are firm and rigid bikes and do not absorb bumps and jump on the trails but full suspension bikes have the ability to act as a bump absorber on hard and aggressive terrains, it is the main reason that hardtail bikes are not comfortable bikes and these are upgraded to full suspension just for comfortability.
The parts of the hardtail bike which is making these bikes hard and rigid are the chain stay tube and seat tube which do not contain any kind of suspension between them and these tubes are strongly connected and welded with the geometry and frame of the hardtail bike which makes these bike rigid in nature so the first option is you have to cut these tubes and also cut the rear side of the full suspension bike ad interchange both of these parts between them, then you will successfully convert and interchange hardtail into full suspension bike, but it is the cheap and first option and the other expensive option is that you have to fully replace the frame of your hardtail bike with the full suspension bike frame, but installing or upgrading the new frame requires all the clamp holes of the full suspension frame compatible with the parts of the hardtail bike, which is almost a vast issue for converting this setup.
Your previous hardtail BB might be not compatible with the new full suspension frame. thread sizes and the diameter and length of the bottom bracket would matter a lot for installing within the shell or hollow drop out of the new frame.
Cranksets include the crank legs which are attached with the bottom bracket, if you are mounting a hardtail crankset with full suspension crank legs then these would not work or install because both of them are non-compatible with different lengths, shapes, structures, and mounting place.
The headset of the new full suspension frame does not accept the head tube of the hardtail fork because there are two types of forks with different sizes.
- Tapered forks
- Non-tapered forks
Both of these forks are non-compatible with different frames based on their threading sizes and the diameter of the head tubes. forks of the hardtail and full suspension are specific for the specific geometries and frame of bikes but hardtail bikes are simple bikes, we can say as in other words, you can name hardtail bikes as simple mountain bikes without rear shocks or suspensions, these are old traditional bikes so you have to look for many things and compatibility when thinking of switching or interchanging from hardtail to full suspension.
Full suspension bikes are new modern and expensive bikes with modern features in their frame and shape of geometry, and the new modern bikes have quick release skewer for mounting and unmounting the rear tires, but old traditional bikes contain thru-axles for installing and uninstalling rear wheels.
You have to look for QR skewer full suspension frame for making the hub and axle of the hardtail bike parts compatible with the new suspension frame, but if the full suspension has QR skewer dropouts and hardtail wheels and hubs are compatible with the thru axles then the setup is non-compatible.
Wheels are not the same sizes, these are of different sizes depending on the bike frame and geometry, there are three sizes of wheels.
- 26 wheels
- 27.5 wheels
- 29 wheels
These sizes of wheels have their specific sized frames and if your hardtail bike has 26 wheels and you are installing 29 size frames on them, the setup will not work and mount, because different sized wheels would work abnormally on different frames, which would affect your riding and learning skills on this new setup.
It is the distance from left dropout to right dropout clamp hole, it is different for different frames which include 10mm, 11mm, 12mm, and 15mm distance. if the dropout spacing of the full suspension frame is smaller or greater than the hardtail hub axle and wheels then it is non-compatible and you have to make dropouts of the new frame compatible with the hardtail parts.
Saddle Tube Diameter:
Dropper post tubes have different widths and diameters and the hollow seat tube of the frame have also different widths for different frames but this is not a big issue because with the help of clamp bolts of the saddle you can easily tight and lose the dropper post and maintain the height of the saddle.
Brake Hose Issue:
After installing a new frame you also have to face to face some problems that might be brake hose issues, the distance of the brake hose might be smaller or greater from the frame and brakes, and you have to adjust its distance by watching youtube videos or from the mechanic shop.
Brake cables and gear shifters are also a major problem when shifting and upgrading a bike frame, may times cables of the brakes and gears are short and long in length, you have to adjust their lengths accurately to avoid their squeezing when you pull the levers of the brake on a different type of hard and aggressive trails.
Length Of The Steering Tube:
The steering tube of the bar would need changing because if the tube is larger in length then you have to cut it and maintain its actual length that should be compatible with the handlebar and stem and if the length of the steering tube is smaller then there is no any upgrade, even the shorter steerer tubes are not welded to raise their lengths, you have to upgrade or buy another steering tube for this setup if the steering tube is shorter.
Converting from hardtail to full suspension it is is not a good step to upgrade or replace bike and bike parts because it will cause enough problems and even you will leave the whole setup because it’s not easy, you can simply sell your old hardtail bike and add more bucks after that buy new full suspension bike, which would be a good and easy step for you.