Tadpole trikes - Rear drive with regen? Issues?

[corkscrew]

So I've read reports on people with rear brakes on their tadpole trikes, and how it's generally not a good idea due to the chance of flipping and whatnot.

Does the same apply to regen?

 

[JEB]

I can dump over 1hp into resistors going down a hill with a direct drive motor, never had any trouble, but I have most of the weight of the trike on the rear wheel (200+lbs) and the tire is 3.5" wide (16" dot hiway rated tire)

 

[ebent]

I ride a catrike pocket with a 750w hub. The regen feels like a slight engagement of the front brakes. It can be used as a brake saver.

 

[amberwolf]

So I've read reports on people with rear brakes on their tadpole trikes, and how it's generally not a good idea due to the chance of flipping and whatnot.

I can't imagine how you could cause a flip with *rear* brakes on a tadpole, although you could certainly skid out sideways if braking in a turn and break traction on the rear.

It's the front wheels on a tadpole you won't want to lockup and still maintain traction, especialy if they are lined up with your knees and there isn't enough weight behind them to keep the rear down. *then* you could cant forward far enough to have the cranks or boom catch on the ground, and THAT would flip you.

That said, on a typical basic tadpole shape, low-slung, 66% of weight on front wheels, then during braking it's just like any other vehicle--most of the weight will shift to the front, so there won't be a lot fo traction on the rear, making it's braking force much less relevant than the front.

Does the same apply to regen?

Regen does the same thing any other braking does, assuming the same force is applied via regen as your brakes (often regen is softer, depending on the controller, settings, and battery (and/or BMS) and SoC).

 

[docnjoj]

Well I'm living proof that you don't want to lock up the rear wheel on a tadpole at 20mph. Mine did due to either a loose chain or a failed brushed controller and it immediately went sideways and then rolled and flipped me. 6 broken ribs convinced me that it was time for a store bought trike after riding my homebuilt for over 5 years. Don't lock the rear wheel at speed!
otherDoc

 

[amberwolf]

Yowch! Well, I guess there are lots of situations my imagination fails me on. I can easily see how you could flip if you end up sideways, cuz once the wheels start scrubbing and stop rolling, momentum would have a way of trying to continue in your previous direction....

I guess if it was a leaning trike it would have a lot less tendency to end up in that position, possibly even able to recover from a complete sideways spin, like a bike can (with a skillled enough rider), with the rider's weight being able to lean over the other way to try to counter it. But on a regular trike you just can't lean far enough while still keeping the weight/force on the contact patches of the right tires and letting them pivot the weight around, so it could just catch and flip easily.

I'm not sure how to prevent ending up sideways, though, except with some sort of traction control system that brakes all the wheels automatically in the event of one failing to rotate as fast as the others, but braking each one independently in such a way as to maintain traction on them all and try to match their speeds, ceasing to brake when all wheels match speed again.

I have very little idea how to do that, as it would require a long list of conditionals in the controls, so it doesn't happen in turns or during deliberate maneuvers by the rider, but does happen in loss-of-control situations.

 

[ebent]

Glad to say I've never fliped due to a locked rear wheel but I know this to be true. Braking the front wheel is comfortable and the best option on a tadpole. I've heard of situations where a piece of debris gets caught in the rear spokes and over they went. Wow other doc, six ribs!!! No fun. Hope that was long ago....

 

[docnjoj]

Glad to say I've never fliped due to a locked rear wheel but I know this to be true. Braking the front wheel is comfortable and the best option on a tadpole. I've heard of situations where a piece of debris gets caught in the rear spokes and over they went. Wow other doc, six ribs!!! No fun. Hope that was long ago....

December 27 2009 was that fatefull day. I was able to ride my trike on electric power alone (very slowly) to the ER a block away. That trike was my 5.0 homebuild version and the accident was my own faulty design fault. Probably chain in the rear wheel caused the lockup. Downhill at 20 mph and the rear locked caused the trike to slew sideways and then roll and flip in maybe 1 second overall. Nuthin I could do. The front wheel brakes are fine and the trike goes straight ahead with front wheel lockup. Rear wheel lockup, well, it's different. I only have front brakes (but 185 mm rotors) on the Steini.
otherDoc

 

[deardancer3]

Doc, same thing with my trike, Tricruiser, locked my rearwheel due to chain in wheel, lost directional control, locked fronts under panic, flipped. I consumed about $50 in supplies from the drugstore and needed a new helmet.

We Join the tadpole end-over club.

anyway, a regen brake would be hard to sustain a lockup, would it not? I mean if it stops turning, it doesnt gen any current to hold it being locked, and a similar thing at very low speeds? I heard regen was kinda like antilock brakes.

I think regen on a tadpole rear might be a very good kind of rear brake.

but, I quite riding trikes. Just cant handle the differences going back and forth between DF, Bents and trikes. Old timers disease or something.

d

 

[docnjoj]

Hey Dick! Sorry to hear you too had a Tricruiser incident. Mine was rebuilt many times over to lower the center of gravity and narrow the track plus lengthen the rear suspension. I just didn't put enough jockey wheels on the chain in V 5.0. Great trike at a great price. I take drugs to thin my blood so I can't afford to be going down on a 2 wheeler any more. Gotta have 3 wheels. As we age a cellphone is more important than any safety device to call 911 with. Oh yeah i cracked my helmet too. Musta hit my head on landing. Good thing for the helmet or i might not be typing this stuff.
otherDoc

 

[An average human]

I have a trike (very homebuilt) which ONLY has a rear brake, and at under 25mph it seems to be controllable, it's very wide and has a lot of weight on the rear wheel. with the rear wheel locked up it goes in a straight line but when cornering the results can be interesting. I can only assume that it is low and wide enough (~1.3m) not to flip easily, after reading this front brakes will be used on version 2.

based on my limited experience i would suggest that instability depends on the trike

http://www.burstbladder.com/BB/transport/timages/IMG_7535_1.JPG

 

[docnjoj]

Hi Human. Wide is important but my design parameters always include being able to ride into the house through the front door. That means about 33" or less width. Center of gravity is also important but I have actually raised mine intentionally on the Steintrike by raising the seat 3" and using 20" front wheels instead of the European 16" that came with it. This in the quest to see over objects better. Certainly lower and wider will reduce the chance of going over. I recognise that I can't corner as fast as I used to and have slowed down. Not a bad thing for an old guy.
otherDoc

 

[John in CR]

anyway, a regen brake would be hard to sustain a lockup, would it not? I mean if it stops turning, it doesnt gen any current to hold it being locked, and a similar thing at very low speeds? I heard regen was kinda like antilock brakes.

Yes, by nature regen IS antilock braking.