Those frames which contain disc brake mounts and caliper mounts where the ut bolts of the disc brake would hold tightly with the frame, all of these bike frames are compatible for installing disc brakes with them, and also very old and traditional bikes do not have mounts for the screws of the calipers of disc brakes which are non-compatible frames for installing disc brakes on them because those bikes would not contain and tolerate new modern functioned disc brakes, all the new bike frames are modern with advanced functions and are skipping rim brakes with advanced disc braking systems installed in both front and rear wheelsets.
Bike frames contain two holes on the rear bushing area of bike frames and also front fork contains two holes for adjusting and installing disc brakes, all of these forks and frames are compatible for installing disc brakes within them. instead of bike frames and forks you also need to check the wheels and hub of your bike, if the hub is larger in length enough to support the installation of disc brakes on the drive side then these hubs are also compatible and also bike wheels need to be placed on one side of the hub so that there should be enough space for the rotors of disc brakes and the calipers.
Including all of these changeable things, the levers of both disc brakes and rims are also non-compatible with each other and you cannot connect rim brake levers with disc brake calipers and rotors, and vice versa. because the potholes of the rim brakes are different from the disc brakes and also cables of both brakes are widely different from each other, rim brakes have simple cables without any internal fluids and oils, while cables of disc brakes contain dot fluids and other mineral oils within them.
Swapping and upgrading from rim brakes to disc brakes on the same bike is usually a lot expensive method because 50% of your bike parts need to be replaced and interchanged with the new parts for making the rim brakes compatible with the disc brakes, instead of this upgrading and spending a lot of bucks on your bike, you can buy a new bike with disc brakes installed in front and rear tires, the main things which you are going to swap or change for disc brake setup are given below:
Difference In Mounting Positions:
Disc brakes are mounted on the lower ends of the forks of bike frames but the mounting position of rim brakes is far different, if your bike frame has a rear mounting triangle for mounting of disc brakes then disc brakes would be easily installed but if the bike frame does not contain two holes for screwing and threading of disc brake bolts then it is impossible to install disc brake in the rear wheels.
Difference In Hub Compatibility:
Hubs of rim brakes are shorter and these do not have enough reach for mounting disc brakes, you have to change or swap the hub of the rim brakes with greater length and thick freehubs so that these have 1 to 2 inches of space from the bushings of the front forks, where you can easily install the rotors and calipers of disc brakes.
New And Accurate Sized Wheels:
Old rim brake wheels are non-compatible for disc brakes, you have to purchase new tubeless wheels for disc brake setup, make sure when you are buying new wheels, the size of the wheels should match exactly with the size of your bike frame and bike fork, for example: if bike frame is 29 size then you have to buy 29 sized wheels, and also if you don’t want to buy new wheels, there are plenty of old compatible wheels which are recommended for disc brakes, these are found in mechanic shops and many of your friends which are selling at sale prices, it’s a great opportunity for you to prevent many bucks spending on new disc brake compatible wheelsets.
New Frame And New Fork:
Old bike frames and old traditional forks do not contain screwing holes for mounting disc brakes, you have to purchase and upgrade the bike frame and bike fork for mounting disk brakes, because using any adapters and welding and drilling holes with the fork and fork bushings is a cheap and temporary problem, and it’s like you are increasing the risk of crashing and failing of disc brakes on rough and aggressive terrains.
You need New Rotors, Disc Brake Calipers, And Disc brake Levers:
Rim brakes are simple and cheap brakes but disc brakes are actually made for dirt bike and motorcycle brakes, upgrading disc brakes in mountain and road biking is a big step in bicycles, you need to buy new rotors with new calipers and disc brake levers and also fluid which is inserted within the cables of disc brakes. rim brakes do not contain all of these brake parts and these are simply installed because these are old and traditional bike brakes.
New Hubs For Both Front And Rear Wheels:
Hubs of rim brakes do not contain enough spacing for mounting disc brakes, old traditional hubs are not compatible with the disc brakes, you have to upgrade both front and rear wheel hubs with the new compatible hubs for disc braking.
Clamp-On Bolts/Disc Brake mount Holders:
These are the accessories and small bike modifications of the front forks which are installed near the QR skewer clamp holes of the forks, these contain two screwed thread bolts, the main function of the clamps is to make rim forks compatible for disc brakes, you do not need to replace your bike forks, you just need to buy these clamp on bolts, these are available on eBay and Amazon, and you can easily get them, without these clamp on bolts it is not possible to install disc brakes on old rim frames.
Disc brake mount holders are installed after the rotors and frame clamp holes or QR skewer mounts would fit tightly these mount holders and these holders do not move from their places, their frame clamps are installed on seat frame tubes by threading the screws within the mount holders. make sure if the nut bolts of the holders are longer and their heads are reaching and rubbing the rotors of the disc brakes, then you have to cut them and make them compatible with the clamp of the mount holder, or if you have any spare screws of smaller size, you can also use them for mounting purpose.
After that install the disc brake adapter on the upper region of the mounting holder and tighten the two bolts of the adapters with the help of a recommended tool or screwdriver. calipers of disc brakes are installed above these adapters. and if the angle and height of the calipers are upper or lower from the rotor edges then you have to adjust the mount holders, and move them upward or downward to accurately the angle and position of the calipers.
Adapters For Non-Compatible Bike Frames:
There are also adapters available in the market that are used to make non-compatible bike frames and rim frames compatible for new dis brakes, and you can easily install your disc brakes on old rim brake bikes, these adapters are heavier in weight and also less recommended for aggressive and hard terrains, but these adapters are the best and recommended for road and pavement trails.
Is It Safer To Convert From Rim Brakes To Disc Brakes?
Hopefully, this setup is not a safer way to upgrade your same bike from rim to disc brakes, the reason is that making non-compatible bikes compatible with disc brakes is easier but you have to face a lot of risks on the trails, many times the hub adapters and clamp on bolts of the forks would break and stop working on the terrains, although it is common and also this upgrading needs a lot of money, you have to change almost all of your bike just for a single disc brake upgradation if you have an old sued rim bike, collect two to three thousand bucks and purchase a new disc brake compatible bike to get rid of old traditional rim brake bike because upgrading and converting from rim brakes to disc brakes is not a safe solution.
Spokes Replacement Due To Length Issues:
Spokes for rim brakes are smaller and shorter in length, while disc brake wheels need greater and longer spokes also old traditional bikes do not cross lace patterns, and front wheels contain a lower number of spokes for installation of the disc brakes, you have to lace front wheel by installing of new spokes and replacement of older spokes for the new disc brake setup.