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This mechanical to hydraulic disc brake converter might be one of the coolest bike gadgets I've found on AliExpress. It’s from a brand called IIIPro (3Pro), costs less than £50, and claims to transform any old-school mechanical shifter into a fully hydraulic braking system, complete with dual-piston calipers!
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In this episode, I’ll show you the build quality, get it installed on a road bike, bleed the system, and ultimately test whether this budget hydraulic conversion kit actually works. Could this be the perfect upgrade for riders running mechanical groupsets or mechanical disc brakes like the TRP Spyre? Let’s find out.
The build:
I fitted the kit to a carbon OG-EVKIN road bike frame with Micro-New mechanical shifters and Shimano 105 R7000 derailleurs to see if it really delivers “hydraulic” performance on a budget mechanical groupset.
Why it’s interesting:
This idea is nothing new, the Giant’s Conduct SL system did something similar back in 2016, but this kit is lighter, far cheaper, and much easier to get hold of.
My thoughts:
-Great braking performance, very close to fully hydraulic
-Noticeably stronger and sharper than any mechanical caliper
-A bit tricky to bleed and mount on the bike
For £50, though… this is one seriously impressive upgrade for anyone wanting hydraulic-like braking without changing their groupset.
AliExpress links - (affiliate links, they help support the channel at no extra cost)
https://s.click.aliexpress.com/e/_c3QXW93H
https://s.click.aliexpress.com/e/_c3hddZxl
Timestamps:
00:00 – Intro
00:46 – Hydraulic converter - Info & cost
02:43 – Bike build overview
04:35 – Hydraulic converter - design & weight
05:48 – Hydraulic converter - install & bleed
07:31 – Siroko sponsor
08:21 – Brake bleed info
11:17 – Use cases
12:39 – Bike reveal and brake test
14:55 – Install issue
16:10 – Considerations & conclusion
18:41 – Bonus clip
Intro roll:
Created by Dev Joshi - http://www.go2dev.co.uk
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Email:
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Please note:
I am not a professionally trained bike mechanic. There can be risks associated with using products that are unbranded, untested, or come from sources where the provenance is unknown. Please talk to a qualified bike mechanic if you are in any doubt.
In essence, be careful, do your research, and cycle safe!!!
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Bike part mentions in this video
Disc-BrakesIIIPRO Bicycle mechanical line pull brake converted to hydraulic brake modified parts
Created: July 08, 2025The reviewer tests the IIIPRO hydraulic brake converter kit, which converts mechanical shifters to hydraulic disc brakes. They state the kit includes two aluminum converters and dual-piston brake calipers for under £50. The reviewer finds the braking performance impressive, very close to genuine hydraulic systems and far superior to any mechanical disc brakes they've tested. They successfully install the kit on a winter training bike, noting the need for proper orientation and bleeding technique. While not as easy to install as integrated systems, the reviewer is very impressed with the value and performance.
AI-Summary
Pros
- Very affordable (under £50)
- Includes two converters and both brake calipers
- Decently made one-piece aluminum units
- Impressive braking performance close to genuine hydraulic systems
- Far better than any mechanical disc brake calipers tested
- Good power and modulation
- Nice solid brake feel
- Split reservoir design handles different orientations well
- Uses standard BH59 hydraulic fittings
- Lightweight (137g per adapter vs 266g for Giant Conduct)
Cons
- Requires 160mm rotors (doesn't support 140mm)
- No proper documentation included
- No bleed nipple on brake calipers (just a threaded port)
- Installation requires finding placement for two separate units
- Can be messy to position neatly on the bike
- May interfere with computer mounts or bike lights
- Durability is unknown (aluminum construction, small delicate seals)
- Not as easy to install as integrated systems
- Requires some trial and error with bleeding technique
- Lever feel not quite as sharp as genuine hydraulic brakes
- Slightly more lever travel and hint of sponginess
- Requires squeezing slightly harder for top-end braking force
Key Points
- Converts mechanical shifters to hydraulic disc brakes
- Uses brake cable to compress piston that moves hydraulic fluid
- Split reservoir design with two chambers and rubber diaphragms
- Lower chamber has timing port for fluid top-up
- Upper chamber catches air bubbles for easier bleeding
- Must be oriented with reservoir at top of system
- Requires specific bleeding technique using correct port
- Uses standard BH59 hydraulic fittings
- Weighs 137g per adapter
- Includes dual-piston brake calipers
