Attaching trailer to ebike

[Zaryn]

The conversation started here: http://endless-sphere.com/forums/viewtopic.php?f=3&t=40375&p=609017#p608648

The problem: my rear axle isn't long enough to attach my hitch. Hitch adapter simply does not fit bike frame (photo to come).

Here's a few photos of what I have to work with:

Unmodified bike.

Washer off, hitch on and positioned correctly, nut is about half-way to two-thirds on.

It's hard to see, but that black plate on the outside of the frame isn't attached to anything else -- it spans the distance between the rear axle and the disc brake. When I took the photo I didn't have a tool handy to remove the top nut.

My dad and I are thinking that a longer axle would do the trick, if one exists. Or modify/create a hitch adapter that would clamp on to the frame.

This isn't an OMIGOSH I NEED THE TRAILER NOW thing since I can pull the dogs with the other bike, but it would sure be nice to bring The Cuteness for a ride one of these days.

 

[Sacman]

What kind of trailer is this? Do you have a link that shows a pic of it?
I'm actually looking at a BOB Ibex or ExtraWheel trailer right now but their
mounts and attatchments to the bike are different and symetric to both sides of the rear wheel.

 

[Zaryn]

It is a DoggyRide Original. Looks mostly like this:

 

[Rassy]

Here's an idea that I have actually just done (more or less the same problem) for a similar hook-up trailer.

I had already put an extension on using the built in threaded holes. I used a piece of 1" x 1/4" alluminum in order to attach a disk brake caliper. Then when I decided to add a two-wheel trailer, instead of attaching it at the axle, I drilled an appropriate hole in the extension and bolted the hitch part there.

Since I just did this yesterday I don't have a long term report, but it seems to work great based on a 1 mile test.

Edit: That black plate looks like a torque arm, probably to keep the axle from spinning when accelerating.

 

[mr.electric]

I have the same trailer. It is really nice to pull it with an ebike. I would recommend taking the trouble to mount the hitch to your ebike even if it means making a custom part.
Could you trace the black plate onto a piece of plate steel and make a new part that has an extra ear to bolt the trailer hitch?

 

[cal3thousand]

Looks like the situation that I will be facing shortly. Currently use a Schwinn Joyrider trailer (It's awesome btw). But I know the axle will be too short for my wife's new bike project, so I plan on making a custom torque plate (As I have seen here) using Stainless that incorporates the hitch in one piece. Two birds, you know the rest.

 

[Zaryn]

How the hitch adapter fits on my Zuma:

How it should really fit:

@cal3thousand, @mr. electric: So, the little itty bitty black bit that is my torque arm/plate -- that whole thing could be replaced with another extended plate to allow room for the hitch? There is metal down in the workshop at work/school, but I have no idea of what kind it is.

My other thought was a custom clamp hitch adapter like what I have, only longer. The hitch isn't shown in the photo, but goes over the bolt and under the knob.

@Rassy: Could you post a photo, please?

 

[d8veh]

You can replace that type of hitch with this type that clamps to the chainstay. Those trailers sometimes come already fitted with this hitch. It's a shame yours didn't because it would have saves a lot of messing about (and money)
http://www.ebay.co.uk/itm/Trailers-Kiddie-Trailers-Avenir-Trailer-Hitch-Stay-Mount-TRA085-/180816567538?pt=UK_SportGoods_CyclAcces_RL&hash=item2a1981dcf2

 

[Zaryn]

I know Amazon isn't the Master of the Universe, but a review that clamp has isn't exactly a high recommendation:

This product, while a good idea in concept, suffers from a rather poor design flaw, which makes it pretty much useless.

The upper arm, of the part that grabs the chainstay on the bicycle, is shorter than the lower arm, which means they do not meet symmetrically on the chainstay. This causes the hitch to rotate, destroying the paint, and on an aluminum-framed bicycle, it will slowly eat through the chainstay itself.

This design flaw is not easily discernible in any of the pictures on Amazon.

If they had bothered to use the same part for the upper and lower arms, then it would work fine.

 

[cwah]

That one seems nice d8ve, I'll receive this trailer shortly:
http://www.ebay.co.uk/itm/Children-Luggage-Cargo-Bicycle-Bike-Trailer-New-Y-B-/120718202513?pt=UK_SportGoods_CyclAcces_RL&hash=item1c1b5d9691

I hope I won't need it

 

[cal3thousand]

I'm seeing 2 different things here. One looks like it just attaches to the axle and the other looks like a dropout grabbing device.

I'm confused, which one is the hitch?

 

[Chalo]

My suggestion: Weld the trailer hitch stub to the torque arm (or to a beefier version of your torque arm). Leave enough room for the nut and screw head.

Chalo

 

[cal3thousand]

My suggestion: Weld the trailer hitch stub to the torque arm (or to a beefier version of your torque arm). Leave enough room for the nut and screw head.

Chalo

That's what I was "trying" to suggest.

 

[Rassy]

Zaryn, my stuff isn't very pretty, but I just use what I have available. Besides, the pannier covers all this stuff. One thing that worked out good, there's a hollow spot on the back of the hitch bracket which is fitted over the bolt head for the bottom end of the caliper, so the hitch bracket can't rotate if the main bolt loosens a bit.

 

[Zaryn]

I'm seeing 2 different things here. One looks like it just attaches to the axle and the other looks like a dropout grabbing device.

I'm confused, which one is the hitch?

The bit that connects directly to the axle is the hitch.

The dropout grabbing device is what DoggyRide calls their hitch adapter. I was lazy and didn't take a photo of the two of them together.

If the computer isn't too taxed at work tomorrow I'll put design ideas together and post them. (I'm in the middle of a HUGE render and I'd rather not crash the computer.) It just helps if I can *see* what we're all talking about.

 

[Zaryn]

Highlighted torque arm:

What I imagine some of you are trying to suggest:

(With the hitch attached to the extra tab.)

Is that even close to what you guys were envisioning?

 

[Chalo]

That's what I was getting at.

EDIT: To be clear, I think it would be best to root the trailer stub on a line running between the axle and the torque arm fixing screw, if that leaves enough room for the fasteners with some tool clearance. Cantilevering an extension tab that isn't screwed down to anything would give the trailer a much greater opportunity to bend the mount.

Chalo

 

[Kingfish]

+1 to the tab extension.

On my trailer, the original configuration was as a push me-pull you/FWD with pusher trailer. The rear axle that passed through the cassette therefore was re-crafted longer to support the width of my custom hitch.

However, this plan did not work at all, and I had to resort to creating a 2WD ebike. The custom axle and free-spinning wheel went on the trailer. There was just enough room for the custom hitch to fit onto the axle:

• If you remove all of the extra washers and stuff, there’s enough room for both a torque arm and a hitch.
• The hitch was 3/8 inch thick ALUM 6061-T6, and I bored out the diameter and had a bronze bushing pressed into it (bushing provided by Ace Hardware and was machined to remove some of the shoulder).
• The torque arm has to be made from steel, and I put one on both sides to prevent the axle from moving vertically within the frame.

This worked for me, but probably not completely possible for you. As an alternative I did study at length exactly the solution offered up by Chalo/Rassy/Zaryn. Extending a tab allows you the freedom of choice on mounting hardware clear and simple. I think it would be a lot less involved with how I ended up doing mine.

~KF

 

[cal3thousand]

I was envisioning a beefier torque plate that covered more of the dropout area, but that should work too.

 

[Chalo]

I was envisioning a beefier torque plate that covered more of the dropout area, but that should work too.

That was my thinking. The axle thread length dictates a practical maximum thickness, though, and that thickness dictates how far you can locate the mount from a line that runs between axle and fixing screw. Picking up that other dropout mounting thread with another screw would buy a lot more stability and integrity.

Chalo

 

[Zaryn]

Gotcha. That draw up will have to wait until tomorrow -- I need to pedal my butt home to get my car to go to my parents' house to get bits and pieces that are needed here at work. (It's not safe to bike the whole way there. )

 

[d8veh]

I know Amazon isn't the Master of the Universe, but a review that clamp has isn't exactly a high recommendation:

This product, while a good idea in concept, suffers from a rather poor design flaw, which makes it pretty much useless.

The upper arm, of the part that grabs the chainstay on the bicycle, is shorter than the lower arm, which means they do not meet symmetrically on the chainstay. This causes the hitch to rotate, destroying the paint, and on an aluminum-framed bicycle, it will slowly eat through the chainstay itself.

This design flaw is not easily discernible in any of the pictures on Amazon.

If they had bothered to use the same part for the upper and lower arms, then it would work fine.

Both I and my friend use these clamps on our trailers and we haven't experienced any problems. Maybe the guy on Amazon had crappy paint on his bike.

 

[Zaryn]

Both I and my friend use these clamps on our trailers and we haven't experienced any problems. Maybe the guy on Amazon had crappy paint on his bike.

Maybe. I did see that same type of clamp on a kid's trailer today at the LBS, but didn't even think to ask the guy about it.

My dad and I talked about the modified torque plate over dinner. He has an aluminum sheet at work that he can use (I forget the dimensions he gave me) to fabricate a new plate, but it would mean leaving my bike at my parents' house for a few days.

I forgot mentioning welding the hitch to the plate to him. I have a potentially stupid question about that one -- are we talking about welding the hitch to the plate without doing anything else to secure it?

What's the benefit of creating a modified torque plate versus creating a dropout grabbing device that would actually fit my frame? To me, it seems that a custom dropout grabbing device would allow for a larger margin of error and/or stress. And, if I ever needed to, I'd be able to swap out the hitch.

EDIT: I hate being such a noob. Aluminum is straight out for a torque plate replacement -- I'll mention that to the old man the next time we chat.

 

[amberwolf]

FWIW, I use basically taht same clamp that came as part of a Bell 2-kid trailer, both on the stay of the Fusin Test Bike, and on a handlebar bolted straight back on the left cargo rail of CrazyBike2, and I fill that trailer with up to a couple hundred pounds of dog food and stuff fairly regularly. Havne't had any issues with it yet, even though it was well-used when I got it, and it's rubber covers over the clamps were coming apart even then. It still holds and clamps fine, even when I accelrate hard from a stop using CB2 (which is now 4KW) with over a hundred pounds of stuff on the trailer plus the trailer weight.

The dayglo spray paint I used on the handlebar has been scraped and flaked by it, but that was expected, as it's rpetty crappy paint, and I didn't even bother to prep the surfaces.

The factory paint on the steel stay of the FTB seems to be in the same slightly damaged condition I acquired the frame in to start with.

After various experiences, I don't entirely trust *ANY* hitch, so I also use a steel dog tie-out cable to secure the trailer to the bike, as well, so that if I do break the hitch somehow, I don't lose the trailer, especially in traffic.