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Does this exist?

Old 10-26-19, 04:07 AM
  #1  
Brian Walker
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Does this exist?

Hello All,

Is there such thing as a transmission feature that could lock downhill coast speeds when towing a moderately heavy load that doesn't involve the break system? I am legally blind and interested in using an e-bike to transport my professional gear (acupuncture med kit & folding massage table) on hillly rural roads. I don't see well enough to coast freely down steep hills with the the added momentum of a tow wagon or cart, nor would I imagine it would be practical to brake continuously going downhill. I am just beginning to learn about bikes in general, and e-bikes, in particular and am appreciative of any advice or experience you might have to share.

Thank you!
Brian
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Old 10-26-19, 05:15 AM
  #2  
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Tandems fairly often come with a rear drag brake to help control descent speeds.
They’re operator-controlled, but otherwise made to do pretty much what you want.
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Old 10-26-19, 05:57 AM
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Scary....
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Old 10-26-19, 07:42 AM
  #4  
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Moved to e-bikes from mechanics forum. You should be able to get more e-bike background knowledge there.
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Old 10-26-19, 08:30 AM
  #5  
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There are some types of ebike motors that do regenerative braking. That means it recharges the battery when active. This creates a braking effect like lowering the gear in a car going downhill. It takes energy to recharge the battery and the braking effect is the consequence.
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Old 10-26-19, 09:22 AM
  #6  
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Originally Posted by fly135 View Post
There are some types of ebike motors that do regenerative braking. That means it recharges the battery when active. This creates a braking effect like lowering the gear in a car going downhill. It takes energy to recharge the battery and the braking effect is the consequence.

Yeah, my OneMotor system has regen braking but it's a friction drive using a belt, so wouldn't be the right thing for the OP. However, the regen definitely slows the bike down to a nice steady descent with my Burley Travoy and 40lbs of dog food on the back. So finding a good mid or rear drive system with functional regen could work. However, I'm more concerned about the OP not being able to see road hazards and having to fix a flat; maybe a mid-drive would be better in that case.
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Old 10-26-19, 10:52 AM
  #7  
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Sit upright. It amounts to air brakes. Something similar could possibly be rigged on the cart.

The problem with dragging the brakes downhill is rims get hot and brake pads get hot. Brake pads melt. Much is going to depend what kind of hills are attempted. Short hills and the dominant effect will be bicycle brakes are very well air-cooled. Long hills could be difficult. The suggestion above to use air brakes will work fine in a wooded area, in wind-swept terrain it could be a handful.

What is being proposed is quite a challenge. Heavy duty transport by bike has historically only been well developed in coastal plains.
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Old 10-26-19, 11:15 AM
  #8  
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A large direct drive motor with always on regenerative braking will do what the OP wants. Some users report hardly ever needing the brakes as their bikes slow down as soon as they stop pedaling, It's a biking experience I sure would not want, but I'm riding for fun and \not using my bike to put bread on the table.

There aren't many commercial ebikes with a direct drive motor large enough to have that kind of braking and also have enough power to pull a trailer up a steep hill. A Radmotor City Bike has that kind of motor, but milder braking, and you and the motor will have to work together on steeper hills, as with all ebikes.

A ebike hobbyist would install a big direct drive motor on the trailer wheel. Set it up with regenerative braking, Battery and electronics in the trailer. With the brakes on the rear, less chance of it coming around on a hard stop too.
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Old 10-26-19, 02:12 PM
  #9  
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Regenerative braking with a large direct drive (DD) motor as already stated by individuals. This will provide good power for the uphills and good regenerative braking for downhill. Ebikekit has a relatively large "slow" motor (read the tutorials at ebikesca) that might work, but the individuals at ebikesca probably have the best experience and kit for you. Also, endless sphere had individuals with more experience with big DD motors than here.
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Old 10-26-19, 03:46 PM
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The least expensive solution is a direct drive hub motor (like this one: https://www.amazon.com/LLY-Electric-.../dp/B07TKGMBJG) for the trailer with a switch (https://www.amazon.com/FULL-THROTTLE.../dp/B07JP46TJP) The motor is to be used solely for braking, so you don't need anything but the hub motor. The three power leads (the big wires) on the motor are connected to the three positions of the switch, and the other three positions are wired together. When the switch is turned on, the motor is shorted and will provide a braking torque proportional to how fast it is spun. Do NOT try to disengage the brake until you are STOPPED.

Alternatively, you use a similar sized 3PDT switch to switch between braking and motor power - WARNING - you should be going very slowly or STOPPED when switching modes.

The wiring to the switch should be 10AWG flexible with very high strand count (https://www.amazon.com/dp/B01ABOPO2S/) The hub motor should also have the ferro-fluid treatment https://www.electricbike.com/ferrofl...-direct-drive/

The braking system I described is not regenerative braking, it is dynamic braking as has been used on diesel-electric locomotives for decades. https://en.wikipedia.org/wiki/Dynamic_braking In this case, the windings in the hub motor are the resistive grid, which is why the ferro-fluid is important. A fan blowing on the motor certainly would not hurt.
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Old 10-27-19, 10:47 AM
  #11  
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Here's a thread from 2013 about trailer brakes.

Trailer brakes
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Old 10-28-19, 10:58 PM
  #12  
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Thank you all very much for your help! I'll check in with these shops, 2old, thanks!

Nfmisso, I shall explore these solutions and do my best to learn about their mechanics as I go, thank you for such a thorough introduction and thank you for correcting my terminology (dynamic braking)!

Another concern comes to mind, how would heat be discipated if the battery bank is fully charged but braking is still continuously applied?
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Old 10-29-19, 09:27 PM
  #13  
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BW; I'm sure you'll see this elsewhere, but with such strong regen, make sure you use one (preferably two) torque arm(s) on your set up.
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Old 10-30-19, 04:03 AM
  #14  
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As mentioned ebikes.ca has the best selection of hub motor kits. Cycletote makes the best and safest two wheeled bicycle carts. They are American made and there is a brake option available for a price.
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Old 11-04-19, 12:27 AM
  #15  
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You might consider looking at the R+M Load or Packster instead of doing the trailer. I don't know if your stuff will fit but you won't have to tow a trailer and while yes you would still be braking downhill rather than locking out speed, the bike is well designed to handle heavier loads of kids and cargo. It take a little getting used to but the Load especially is a fantastic bike and rides really well. Potentially your local dealer (which may not be super local) could install bigger rotors (and all the needed adaptors) on the system but the stock is pretty good especially with the 4 piston brakes. I would go with an RT86 IceTech rotor in 203mm at the rear and see if you can put a 180 at the front if you are worried about it. Plus the new 2020 stuff will have the new Bosch Cargo specific motors so you can get better torque and a motor designed for handling heavier loads.

Yes the R+M stuff is more expensive but it is some of the finest cargo carrying bikes that exist.
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