Building my first trailer - dropouts vs through frame etc.

[amberwolf]

It's intended to fit between bike trail bollards - my plan is to make it 3' wide as I'm unable to find any sort of standard that exists even in the greater vancouver (BC) area. I'd like a little more space - 4' would be IDEAL - but I was worried about narrower bike lanes so was trying to constrain it to the width of a trike.

That is part of why the SB Cruiser trike is the width it is (also to fit thru a typical house front door), but I would like to build one at least a foot wider for certain cargo types (and more room for the Saint Bernards I have). (can't use it for work commutes though, because it wouldn't be able to be brought inside to keep people from messing with it or stealing it).

Around here, the bollards and such on paths (including the canals) are typically 4 feet apart--too narrow for (most) cars/etc to fit thru but wide enough for a couple of cyclists to pass closely together, etc. Sometimes there's a few inches more. I've run into a few freshly-installed ones over the years on "sidewalk paths" that are narrower spaced, so much so that some people in wheelchairs wouldn't be able to pass thru, and they usually aren't there the next time I pass by (months or years later).

My Mk IV/V trailer is just about exactly narrow enough to fit between the narrowest of the 4-footers, sometimes with a few inches to spare, sometimes scraping paint. Most recent test of that was several weeks back when I used it to pick up an ancient Schwinn trike and a few other junk bikes; most of the ride was along the canal paths

The SB Cruiser : Amberwolf's 2WD Heavy Cargo Trike & Dog Carrier

I appreciate the thought, but there's no "chassis" around that I can just use as-is--I'd have to cut it up and build a new trike that suits my specific needs out of it. (the only thing that I've seen that comes close to what I need was the TruckTrike, but even that would have to be modified). I...

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Trailer threads
Amberwolf's Flatbed Kennel Trailer Mk IV

Amberwolf's Flatbed Kennel Trailer Mk V

New version for the dogs; usable for cargo too, with removable air conditioning for the dogs (if the parts I have work out). Previous versions are here: https://endless-sphere.com/forums/viewtopic.php?f=2&t=18671 and here: https://endless-sphere.com/forums/viewtopic.php?f=2&t=54323 and here...

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I had a plan to install a pair of ex-Jumpbike hubmotor wheels on it, along with a pair of drumbrake wheels from the same bikes, but I use it so seldom that I haven't been able to justify the time required to do this (too many other things with much higher priority to get done that still aren't).



Bike lanes themselves around here are sometimes not even wide enough to fit a bicycle plus rider in--they can be narrower than the handlebars or your butt. :/ But usually they're more than wide enough. The worst ones are those between parking "lanes" for cars and the street traffic, but you should never ride in those because you'll get doored or else pushed into a parked car by a passing truck's or bus's wavefront, or someone will step out from between vehicles right in front of you, etc., so I don't really care how wide or narrow they are.

 

[amberwolf]

It will be self assisting - will be riding a bike in fron

In at least one of my trailer threads, there is some discussion of systems to do automatic braking, and should be some about auto-assist.

 

[amberwolf]

I understand the concerns re repairability - it's cool to be able to have that discussion with somone else who's been on the fence themselves. I estimated about 50 pounds difference in total weight - which is about 10% - it makes a fair difference in daily range based on the motor simulator Grin has online - but I was also thinking about the dissimilar metal corrosion issues I've seen lately. Bike motors, brakes, shocks, etc. are all aluminum. If I had a steel frame and sprinkle in some road salt, I wondered about the galvanic reaction - with steel I could patch a cracked weld myself - but I'd probably also have to powder coat it. Thing is it's been a challenge in a big city to find a fab shop with time to work on it - so that's pushing me to reconsider steel again - so I'm conflicted too. But that corrosion issue could be big being in the outdoors in all weather. I'd appreciate any other thoughts you have. Would you paint or powdercoat steel? Milling is harder for custom parts

Mind you, it's fairly dry around here, so corrosion isn't as big an issue as it is where you are, and we don't salt roads, etc (no snow). All my bikes/trikes/trailers sit out in the weather all the time (parts and stuff may be inside or in the sheds, but not room enough for the completed items). But the cheap crappy recycled steel (mostly from old retail fixtures, crappy steel furniture, etc, junk bikes, and so on) I've used for most of my projects hasn't corroded much beyond surface rust even though I usually don't paint them after removing whatever paint/etc was on them around the weld areas and doing the welding. This is really because it costs a lot for paint, and if I had money I'd probably set up my own powdercoating shed, and do that and/or paint things....but it's also because people steal nice looking things, and if they look like crap they often get left alone.


I have built one trailer out of an aluminum panel (used to be the front of a big rackmount computer) and some steel bracings under it, bolting on wheel mounts, trailer hitch, etc., and while I didn't get much corrosion, I did get a lot of stress fractures, etc., so I wouldn't do that again. :/


I personally prefer steel because I could do roadside repair breaks in it in a number of ways--if I was really desperate I could even use a traction battery and a steel rod (maybe even a screwdriver) to weld it temporarily to get home where the real welder is. (have so far never had to try that for real, but have tested the theory once and it would "work", if crappily).

Also, there's plenty of warning before the steel breaks--you get squeaks, creaks, etc., visible deformations, and so on, where sometimes other materials just fail BAM and you're stuck...


I don't have a mill, so can't say how much harder steel would be to work than aluminums, but I have a lathe (that I can sort of use); mostly I do fairly crude angle-grinder-and-file work for "machining" parts. (I'm a practical hack, not an engineer).

 

[amberwolf]

I haven't really figured a way to drop the floor. I know the center of gravity will be high. But the frame design gets a LOT more complicated to maintain some ground clearance, allow for suspension, and have the floor below the axle. In theory I could do it by making the wheels independent.

You might look at my MkIV/V trailer; it's deck is hung well below the axles. Works much better than the others I built above the axles. I can use large-diameter wheels for a better ride, and still have a low deck (and sufficient ground clearance).

I really don't recommend small diameter wheels, especially for something to be used on totally unknown road/path surfaces--you might run across holes/bumps that are "impassable" with smaller (20" etc) wheels that would be ok with bigger ones (26" and up).

Also much easier to do roadside wheel work--I don't have to unload the trailer to change a tube/tire/etc. (I can even just carry a spare wheel and swap it right out).

 

[amberwolf]

Because of that very issue - I need regen however I didn't want to end up on my first ebike trailer build to be going back and forth between a motor company, no warranty due to the weld, and a separate controller company etc.
Grin is close - they seem to cater to DIY - which is better than a big company catering to bike manufacturers I think. I might do it again after the first one, but I figured I'd try to keep it simple. Their motors have a good reputation - and are reported to run well under load due to a liquid cooling injection ("statorade") - I've seen motors for much less - however I've also seen a lot of broken motors amoung friends and ebikes - considering the weight of the trailer and the miles I intend to put on it - I didn't want to cheap out on something like a motor and have it blow out in the foothills. I'd be interested to hear other people's ideas - but mine was one of simplicity - had to make some decisions and this seemed to be easy (if more expensive than some).

Grin makes the GMAC with no clutch. I'ts pretty expensive, but it does have power and torque. However, it is VERY noisy in smaller (20") wheels at any significant speed, especially under load (accel or regen). Not so much in bigger ones 26" and up.

They also have (or had?) a Shengyi with welded clutch.

But geared motors of any kind aren't going to benefit much, if at all, from statorade / ferrofluid (there's been a number of discussions about that here over the years you can poke around for).

Also, gears can break or shear from a number of situations (bumps at the wrong time/conditions, overheating, overtorque, etc).


DD hubmotors are very simple to use for regen, and direclty benefit from FF/SA, and are cheap, and don't ahve any gearing to break. But they take more power to do the same acceleration job all other things being the same about the system.


It is more complex, but there's a third option of using a simple DD hubmotor (or whatever) to drive the wheel via chain (or belt), so you can optimize the gear ratio with the sprockets, and still use the best motor for the job vs cost, *and* use large-diameter wheels for better ride/etc. This is what I'll be doing with the new trike version over here:

Amberwolf's Schwinn Trike Rebuild / Conversion to Heavy Cargo Hauler

From here: https://endless-sphere.com/sphere/threads/the-sb-cruiser-amberwolfs-2wd-heavy-cargo-trike-dog-carrier.67833/post-1827806 I got an old Schwinn Tri-Wheeler Town and Country (probably the 1971 or 75 or 78 model, based on info from bikehistory.org) from someone I knew from the...

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vs the various kinds of hubmotors I've experimented with in small wheels on the SB Cruiser trike over the last decade.

 

[Chalo]

But the frame design gets a LOT more complicated to maintain some ground clearance, allow for suspension, and have the floor below the axle.

Suspension? I missed that detail. The only way I'd consider using rear suspension on a trailer with hub motors in those positions would be with leading link swingarms, to resist torque jacking and to divorce the axle height from the deck height.

Trailing link would work well with unpowered wheels; leaf spring suspension would would work fine with powered wheels but would complicate getting the deck even nearly as low as the axle. But leading link pivots could sprout off the upper frame rails, without any tendency to lift the trailer frame under power. It might squat a little when pulling hard.

 

[MitchNotMitchell]

In at least one of my trailer threads, there is some discussion of systems to do automatic braking, and should be some about auto-assist.

I'll look for that... Curious how they did it. I have my own idea based on a feedback loop using a load cell and a microcontroller but I can imagine ways to do it analog my electronic smarts aren't what they used to be.