Best hitch point, stem or axle ?

[Luka]

What do yu think is the best place to hitch the trailer ?

Seat stem, or rear axle ?

Why ? Please explain.

 

[Mr. Bill]

I too would like to hear responses to your question. I've devised a plan to attach a push trailer to the rear axle for my first build. It seemed to me that attaching at the axle was a more direct approach but only slightly more complicated. Of course this not from personal experience yet. Looking forward to more input.
Bill

 

[loquin]

It would seem to me that attaching at the rear axle would be a more stable approach... especially when making turns. Assume you have to go wide open throttle while in the middle of a low speed turn - wouldn't you rather have the push on the bike low, rather than high?

actually, I would rather have a trailer hitch. A U-shaped axle attachment, similar to a heavy-duty fender brace, extending straight back. Use an eye-bolt (rather than a ball) as the curved inner surface allows some up/down/tilt trailer movement.

Note in the sketch, below, that I show the hitch bars as being parallel. It's just easier to draw parallel with paint - the hitch should spread wider at the axle - this gives more lateral strength. If you extended the bars past the axle to the front, you could fasten it to the bottom stays with a u-bolt, and maybe not need a brace.

 

[Mr. Bill]

That sounds a lot like what I have in mind but rather than u-shaped piece attached rigidly to the frame, attach it at or near the axle to allow it to pivot up & down. Then attach the rear half of the trailer at a side to side pivot point at the center of the rear of the u-shaped piece. This would allow up and down movement at the axle and side to side movement for turns. Bill

 

[ZnsaneRyder]

I've tried both when I built my last trailer...........

I first tried the axle approach, but the weight of the engine made the balance really bad, so then I made the hitch go to the seat post, and the balance was MUCH better. Also, with the axle approach, the engine pushing against the rear wheel caused the wheel to slide on dirt on turns, which was scary.....

The trailer pushing up high on the bike is fine, because your body weight on the seat controls the bike. It pushes you in the direction you want to go.

So far, 54.8mph topped out once, and it is stable at any speed.

 

[Luka]

I've tried both when I built my last trailer...........

I first tried the axle approach, but the weight of the engine made the balance really bad, so then I made the hitch go to the seat post, and the balance was MUCH better. Also, with the axle approach, the engine pushing against the rear wheel caused the wheel to slide on dirt on turns, which was scary.....

The trailer pushing up high on the bike is fine, because your body weight on the seat controls the bike. It pushes you in the direction you want to go.

So far, 54.8mph topped out once, and it is stable at any speed.

At this point, I am leaning toward seatpost attachment. For pretty much the reasons you list.

My bike is full suspension:

I'm thinking that if the pusher were attached to the axle, it would tend to 'push' the rear wheel up 'under' the bike. Plus there's that wheel slide on dirt curves, which you mention. I live on a 3 mile long gravel road. With some very steep hills, and one very steep, treacherous switchback.

I think that it would be more difficult to get used to having the rear wheel pushed around, than having the PT push against my own, (rather voluminous), weight, on the seat.

There is also the fact that an axle connection would be more difficult to move from one bike to another, than a seatpost mount.

 

[Dennis Becraft]

Definitely use the seatpost, especially if you are building a single-wheel pusher trailer. As mentioned, your trailer will have "really bad balance" with a lower attachment point. Top heaviness requires a very sturdy, heavy, zero tolerance hitch. Make every effort to enable your trailer to stand up vertically by itself when you hold the tongue in position. If it stands up on its own, a lightweight, simple, looser hitch will work just fine. If you are building a pusher with more than about 5 HP, AND IF YOU HAVE REAR SUSPENSION, you will experience a lifting effect under strong acceleration. The upward angle of the push will be helped by the spring in the suspension. Making your trailer a little longer than necessary between the engine and the wheel reduces that angle and helps lower the center of gravity of the trailer. Imagine a line from your hitch to the place your tire touches the ground. You have to arrange for as much weight as possible to be as far below that line as possible to enable the trailer to be the opposite of top heavy.

I've never had the occasion to open the throttle in the middle of a low speed turn. Nothing unmanageable would happen because the trailer has a ratio for speed. It doesn't have irresistible acceleration like it might have with a CVT or some other transmission that allows for a low intial first gear type ratio.

 

[BikeMan]

Those that have experience with bike pushers will always tell you the seat post is the best place.Look at this you tube video,it will show you just how much control and precision a seat post pusher has.

http://www.youtube.com/watch?v=xp5xRazHd7g

 

[Rgvkid]

The main thing about using the seat post is to mount it as low as possible or even on the bike frame post sleeve if possible. These will put less stress on the aluminum seat post and better center of gravity with the frame.