Poor Man's RV

General Discussion about electric bicycles.
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wturber   1 MW

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Re: Poor Man's RV

Post by wturber » Jun 16 2019 4:25pm

Hmmm. How 'bout this?

https://www.novosport.de/206/bikes-products/cogito
Image

Didn't see a U.S. dealer and its probably expensive.

Backing up a bit. If you aren't planning on frequent 100+ mile days and are shooting for 50-ish instead, then an upright e-bike should work fine. That's only about four hours or so in the saddle each day at moderate effort. And that shouldn't be bad at all on good fitting upright bike in my experience.
"Commuter - DC Booster"
Iron Horse 3.0 hardtail - 48V / 1000W / 470rpm generic Chinese DD Hub motor (ebay)
8 x 36v 4.3ah 10s 2P battery packs - 1500W 30A DC Boost Converter delivers 54v and about 1000 watts peak
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donn   1 kW

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Re: Poor Man's RV

Post by donn » Jun 16 2019 6:29pm

I like two wheels because it's more fun.

For myself, I'm not real interested in designs that put the cranks above the seat. It's awkward, and some people think you lose a little functionality because of blood flow or something. I know a lot of people go there, so it can't be all that bad ... but wait, a lot of people ride upright bicycles, so never mind that logic.

For motorized, as I've said before, rear suspension is a big step up. With that, you can load the rear wheel way up, with a load platform cantilevered out back off the suspended frame. I bet the frame only needs to be a little longer, and the seat a little forward, to change the feel of the ride quite a bit; shifting the weight forward should improve (I think) slow speed stability a little, maybe lose a little high speed stability but (even) less sure of that.

I wonder how Justin set up that steering linkage. The hard part might be tapping the bolt into the front fork crown - could be easy, depending on the fork, just have no idea. Mine already had it, so I only needed a new rod with "rod end bearings" on either end, which was just an aluminum tube with sawed off bolts inserted and pinned, and female rod ends screwed on. It adds one more item that gets in the way of things around the frame, but it's way better than big "tiller" steering bars. Geometry isn't critical, handles surprisingly independent of the exact steering ratio.

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amberwolf   100 GW

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Re: Poor Man's RV

Post by amberwolf » Jun 16 2019 10:15pm

donn wrote:
Jun 16 2019 6:29pm
I wonder how Justin set up that steering linkage. The hard part might be tapping the bolt into the front fork crown - could be easy, depending on the fork, just have no idea. Mine already had it, so I only needed a new rod with "rod end bearings" on either end, which was just an aluminum tube with sawed off bolts inserted and pinned, and female rod ends screwed on.
On CrazyBike2, I used remote steering by welding a tab to the bottom of the steering tube attached behind the seatpost (my frame is a bit different than Justin's), but it could've been done by using a clamp (stem?) on the bars near the pivot, with a bolt for the heim joint (REB) pivot. Then I used a steel stem on the fork's steerer, and welded a tab on the side of taht for the other end of the rod's heim joint. (couldve been done by drilling a hole in the stem itself if it ws the right shape). Originally itwas a BMS stem and I directly bolted the rod to one of the stem's clamp bolt holes.

If the stem used on the bars is solid metal (alumimum, etc), a hole could be drilled in it for the bolt, and tapped for the bolt threads.


Here's a link to one of my posts about the CB2 setup, with the sturdier version of the handlebar end, using actual heim joints and threaded rod:
https://www.endless-sphere.com/forums/v ... 0&p=956012

and here's the original tie rod build from scrap parts and recycled bits:
https://www.endless-sphere.com/forums/v ... 0&p=325230

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Chalo   100 GW

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Re: Weight Load

Post by Chalo » Jun 17 2019 12:39am

kauaicycler wrote:
Jun 16 2019 9:02am
As part of my research I found the same bike, one stock the other electrified, and they had different load limits. The stock one had a weight limit of 300lbs the electrified one had a limit of 250lbs. I imagine part of this to be the weight of the extra components like motor and battery (geared hub motor) but what other factors would contribute to this difference? I assume the hub motor wheel build has something to do with it such as spokes used etc.
I'm sure the difference in rating has to do with the hub motor. Maybe there's concern about lugging and overheating it, maybe there's concern about the capacity of the gear reduction, or maybe it's just a matter of hub motor wheels being a whole lot weaker and less reliable structurally than normal bicycle wheels.

If you're going to use a rear hub motor, try to get one that can be laced up with approximately equal bracing angle on both sides. (Grin's spoke calculator is a great help in figuring this out.) Make sure to lace all the spokes with their heads inside the flange, to maximize what little bracing angle is available. Use 14-15ga double butted spokes, with washers underneath the spoke heads if the hub's holes are too big for 14ga spokes. Use a good wide rim that has plenty of stiffness on its own, because the hub won't help as much as a normal hub.

My own e-bike regularly exceeds 500 pounds with me and some cargo aboard. Both the front hub motor wheel and the rear wheel are symmetrical, laced up tight with 14ga spokes and sturdy but relatively normal rims. Both have been trouble-free so far.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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