How to Choose a Hydraulic Disc Brake
Pick your riding type first, then the piston count. Those two choices narrow our range to a few brakes, and the details below settle the rest.
Start With How You Ride
Each LEWIS brake is built with a type of riding in mind. This table shows where we would begin.
| Riding | Start with | Pistons |
|---|---|---|
| Downhill and enduro | LH4, LV4, LHP S4, AX | 4 |
| Downhill, enduro, all-mountain | LHT, LHT-II | 4x17mm |
| Enduro, XC and trail | AE | 4 |
| XC and trial | LV-S2 | 2 |
| BMX, XC and gravel | LV-BB | 2 |
| Road, flat mount | R2 caliper | 2 |
| Heavy MTB, heavy e-bike | LHP+ S6 | 6 |
If you ride an electric off-road motorcycle, our e-motorcycle guide covers that separately.
Two Pistons for Light Bikes
Not every bike needs four pistons. Our LV-S2 uses two 21mm stainless steel pistons and is designed for cross country, trial, BMX and dirt jump bikes.
The LV-BB pairs a BB2 flat mount caliper with a lightweight LV lever for BMX, XC and gravel. On the road side, the R2 is a monoblock flat mount caliper with two 21mm titanium pistons.
Four Pistons for Trail and Gravity
This is the biggest part of our range. The LH4 uses 14mm and 17mm stainless steel pistons with TP-37 pads. The AE also runs 14mm and 17mm pistons, with a firmer lever feel than the LH series, for riders who want more feedback.
Move up to the LHP S4 for independent cooling fins, or to the LHT for 4x17mm titanium and ceramic pistons. The AX goes bigger still, with 18mm and 20mm pistons.
Six Pistons for Heavy Bikes
The LHP+ S6 has six 14mm pistons and is built for heavy mountain bikes and heavy e-bikes.
Its caliper has a +20 adapter built in, which matters when you work out your rotor size. Count that first, then read the adapter guide.
Axial and Radial Levers
LEWIS labels each lever as axial or radial cylinder. The LH4 and LV4 show how close the two can be: same 14mm and 17mm pistons, same 380g set weight without hose. The LH4 has a split clamp and the LV4 a hinged clamp, so this is mostly a choice of lever layout and clamp.
Which Fluid Each Brake Uses
Use only the fluid your brake is specified for. Most of our mountain bike range runs on mineral oil, and the bigger e-moto brakes run on DOT 5.1.
| Fluid | Brakes |
|---|---|
| Mineral oil | LH4, LV4, LV-S2, LV-BB, LHP S4, LHP+ U4, LHP+ S6, LHT, LHT-II, AX, EB 20-21 |
| DOT 5.1 | EP6-II, EP8-II |
| Mineral oil or DOT 5.1 | R2 caliper |
Lever Adjustments
Dual adjustment gives you lever reach and bite point, and you get it on the LH4, LV4, LV-S2 and LV-BB. Triple adjustment adds leverage ratio, and you get it on the AX, LHP S4, LHP+ U4, LHP+ S6 and LHT.
On the AX, reach and bite point are tool-free. The LHT-II has an upgraded leverage ratio adjustment with precise reach adjustment.
What Else to Check Before You Buy
A brake is only one part of the setup. Go through this list so everything arrives ready to fit.
- Rotor size and thickness: see the rotor guide
- Mount type and adapter: see the adapter guide
- Pad compound: see the brake pad guide
- Bleed tools and fluid: see the service guide
Ask Us About Your Bike
Email us your bike, your riding and the brake you have in mind. We will tell you what we can confirm from our specs.
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