Can I convert my rim-brake bike to hydraulic disc brakes?

By Crankworthy · Published · Updated

It depends

Only if your frame and fork already have disc brake mounts, and your hubs accept rotors. If the frame has rim-brake bosses only, there is nowhere to bolt a caliper and no reliable way to add one.

Where on your bikeBrake mounts, by the rear dropout and on the fork

A disc-ready frameSide view of the rear dropout: two caliper mounting tabs on the stay, within reach of the rotor, hold the disc brake caliper.1 · Disc-ready frameaxlerotorcaliper tabsTwo bolts by the dropout hold the caliper.A rim-brake-only frameSide view of the same corner on a rim-brake frame: the brake bosses are high on the stay, at the rim, and there are no caliper tabs by the dropout.2 · Rim-brake-only frameaxlerim-brake bossno tabsNothing by the dropout to bolt a caliper to.
Check the fork the same way: disc tabs sit low on the left leg, by the axle. Schematic, not to scale.

Why

A disc caliper bolts to mounts built into the frame near the rear dropout and onto the fork leg. Those mounts carry the braking load, so they are designed into the frame from the start.

The hubs have to take rotors too. Rim-brake hubs usually have no rotor mount, so a conversion often means new wheels as well.

If your frame and fork do have disc mounts — some bikes were sold with rim brakes on disc-ready frames — the conversion is straightforward. On a rim-brake road frame without mounts, the practical upgrade is better rim-brake calipers and pads.

How to check for disc mounts

Rear
Look for two threaded tabs or a flat mounting surface on the frame near the rear dropout.
Front
Look for matching tabs on the lower left leg of the fork.

Skip

Don’t buy: a disc brake set for a frame without disc tabs
Instead: better rim-brake pads or calipers.
Don’t buy: disc wheels before checking frame and fork
Instead: look for tabs on both first — the wheels are the easy half.

Bikes this applies to

From our research, these bikes are listed by their maker with rim brakes. Check the frame and fork for disc tabs before planning a conversion.

Hydraulic disc brake sets

For frames and forks that already have disc mounts. Check the mount type and your rotor size.

Prices were last checked when the catalog was built and can change at any time. Retailer links are affiliate links; we may earn a commission at no extra cost to you.

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