Shimano hydraulic regen brakes

[serious_sam]

Modified Shimano hydraulic brake lever for proportional regen.



Parts:
- Shimano BL-MT200 lever SHIMANO Hydraulic Disc Brake 3-Finger Steel Lever | SHIMANO BIKE-EU
- 500psi pressure transducer, 1/8" NPT 500PSI Pressure Transducer Sender Sensor Stainless Steel For Oil Fuel Water | eBay
- 1/8" NPT tap 1/8 - 27 HSS NPT Taper Pipe Tap High Speed Steel Thread Taps&xg | eBay

Process:
1. Drill the M8 thread at the end of the lever to Ø8.5mm.
2. Tap to 1/8"NPT.
3. Thread sensor in carefully, using your preferred flavour of pipe sealant.
4. Bleed lever using mineral oil, tipping on end (sensor downwards).
5. Optional: trim sensor electrical connector down to a reasonable size, solder on wires, and pot with polyurethane sealant and heatshrink.

The sensors are 3 wire:
- 0v
- 5v in
- Signal out @ 0.5-5.0v (proportional to pressure)

The MT200 lever:
- Piston: Ø10mm
- Piston lever length: 13mm
- Finger lever length: 70mm
- This outputs 500psi @5kg lever force (I found that 5kg is a reasonable pull force for braking).

Result:
- My main hydraulic brakes are Shimano Saint, and I use 1 finger. The levers are relatively short.
- I still have my rear hydraulic brake installed for redundancy, I just rotated the lever down a bit and out of the way.
- The MT200 has a longer lever, so it can be mounted further inboard and still have correct placement for index finger reach.
- Firm braking pressure outputs the full 5v. It is well matched to my front hydraulic lever.
- Don't pull the lever in with 4 fingers as hard as you can. You will pop the sensor. Don't ask me how I know. If you were that worried, you could try to find a 1000psi sensor.
- Operation with the Nucular 12F controller is very smooth and proportional just like a "real" brake at anything above walking speed. YMMV (controller dependent).
- I consider it a successful experiment, and a decent upgrade from the thumb throttle I was previously using.

 

[99t4]

Have you ever had a moment of confusion selecting the proper lever under an emergency stop situation?

 

[serious_sam]

Have you ever had a moment of confusion selecting the proper lever under an emergency stop situation?

The regen lever is in the "normal" position, and works perfectly well in an emergency stop situation. It feels exactly like a hydraulic brake in both modulation and power (it has the power to lock the wheel).

The only reason it wouldn't work is if my pack voltage is too high for regen (start of journey), or failure of the system at that exact moment (unlikely).

It also doesn't work when stationary, so if I want to hold the bike still with my left hand (rear brake LHS, front brake RHS), then I can grab the lower hydraulic lever.

TBH, I don't really need the rear hydraulic brake now, but I don't really gain anything by removing it, and having it there as a backup isn't a bad idea.