What's new

Building A Trailer Hitch

Have you not thought of an attachement that conects at the bottom of the rear stays and uses the Quick release to lock in to place?

mixer8rackhitchidea2.jpg


The load doesn't have to be shared over multiple joints or angles and if it does fail then it doesn't require huge amounts of engineering.

Also all of the forces are in one direction rather than multiple. Other ideas could be based around the hitch clamping to the bottom of the stays thus spreading the load over a wider area.

I have looked at the lower mounting point, but from my research online, a higher mounting point, with a low slung trailer (center of gravity below the axle) is the most stable set up for hauling heavy cargo.

To quote from Tony's trailers......

See the two pix that I have marked with what I call "the line of stable equilibrium". Sound slightly nautical and if you have ever wondered what kept your boat from overturning you may have run across a similar term at least with that word mentioned
highhitch.jpg

Low hitch, less stability.

lowhitch.jpg

High hitch, more stability.

This line runs from the pivot on the hitch to where the rubber hits the ground-which is the point at which the forces act that are trying to tip your trailer over (This applies to trailers no matter how many wheels they have and this is contrary to popular belief that these forces act at the height of the hub of the wheel).

All weight below this line tends to keep the trailer upright with no twisting moment on the hitch. Thus the higher the hitch and as low as the trailer can go and still have adequate ground clearance the better.

The two pix clearly show the larger volume available to the trailer with the seat-post hitch. It works out to about five times greater than the axle hitch can provide.

All of this translates into more stability when loaded, especially as we now know where to put all the heavy stuff. So it looks like the load is 500% more stable by using the seat-post hitch.

The other advantage of the seat-post hitch is the potential for carrying heavier loads because with all single wheelers the bicycle gets to share half of the weight of the cargo. And the high hitch loads the bike forward of the back wheel axle-see intro to cargo trailers which of course is far superior to dangling it off the back axle or worse- behind the back axle-or worse again behind the back wheel

Ground clearance was mentioned and it seems that in practice 4 inches is adequate even for most off-road stuff.

You will notice that to get this clearance on most single wheelers that hitch onto the rear axle you have to run 12.5" or 16" wheels. Talk about sluggish!

With the SST you can have any size wheel you want, still have the low ground clearance and thus maintain the higher stability factor. And enjoy low-low rolling resistance especially off-road!

While the pics and the text talk about his single wheel trailer, it also applies to a two wheeled trailer, and the larger wheel size he talks about is also important.

I thing with the very skookum rack I'm building which will also be able to function as a rack and carry the two panniers, I will cover all the bases. I will have to modify the trailer again, I think this will become ver 2.5 :D

Please keep the suggestions, and observations coming, I'm not rejecting anything out of hand, all of your comments make me think, and evaluate what I'm doing, for that I'm grateful, thanks! :D
 
Custom Rack

Definitly keep us posted on the custom rack, I would love one and would pay good money for you to fabricate one!
 
Definitly keep us posted on the custom rack, I would love one and would pay good money for you to fabricate one!

While I would love to make one for you, I'm losing sleep and stealing time just to make one for myself :eek: I work about 12 hours a day at the L shop, sometimes I can steal an hour or so here and there, but mostly I get home around 2 AM, and if I want to work on stuff in my workshop, I get up around 8 AM and head to the Dungeon, that means only 6 hours sleep, I usually need/want closer to 9 :D

Back to the rack and hitch idea.....

Some quick head scratching and some bad drawings, and this is what I came up with.....

Mixer_8_hitch_rack_mockup_2.jpg

OK This is what I was thinking, the hitch would be at the rear of the rack, but this would put the pivot point well behind the center of the rear wheel, and the weight would be quite far behind the rear wheel, I do not think this is a good idea

Mixer_8_hitch_rack_mockup_1.jpg


With this set up, the blue stud would be removable, I could take it out when not towing the trailer, and have full use of the rack. This set up places the weight of the trailer over the rear wheel, and the pivot point over the rear wheel.

The rack I will make will be a bit longer than most, I want to be able to put my panniers on the bike, but with the very short chain stays of this bike, I need some extra room for heel clearance.

Well, what do you think of these ideas? :D
 
Stu - I htink you can make a more simplified 5th wheel point by using the seatpost clamp exposed area plus the seatstays gusset below. You want to get the mount point as forward as possible under your center of mass. Otherwise you are gonna have one whippy beast to control on any downhills. Also - by moving the pivot slightly forward, you can get more weight transfer to the center of your bike (front and rear wheel) which will be more stable (basically repeating myself). The force vectors will be highest down the seat tube - which will naturally 'tension' the chainstay and downtube. Putting the pivot too far back and you are reducing the seat stube vector and increasing load just directly on the rear wheel axle. Counterpoint to this idea is simply that having the pivot point more forward would possibly incure more lateral instability as the force is higher up the seat tube - side to side - so - you need to make sure your load is balanced so as not to have too much tongue weight.

As result -

1) Pivot more forward = more 'push' stability and linear tracking.
2) Pivot more rearward = allow more tongue weight at a cost of less 'push' stability but more lateral stability.
 
I'm not 100% sure what I'm going to do with the mounting point for the hitch yet, but I have got a good start on the rack....

Mixer_8_rack-hitch_build_1.jpg


Mixer_8_rack-hitch_build_2.jpg


The rack is kind of long, but this is to accommodate my panniers on the rack, because of heel clearance. It is mostly just tacked together at this point, so there is some more welding to do.

I'm wondering if I should put a third support in from near the front of the rack to the center main vertical support...? That really might be overkill :eek:
 
I'm wondering if I should put a third support in from near the front of the rack to the center main vertical support...? That really might be overkill :eek:

Actaully that was going to be my suggestion only with one additional feature. You use it to connect the hitch.

mixer8rackhitchbuild1.jpg
 
Actaully that was going to be my suggestion only with one additional feature. You use it to connect the hitch.

mixer8rackhitchbuild1.jpg

Man, you drawings are worse than mine :D But I get your idea. :thumb:

The thing is I think that the hitch that far back is a bad idea, in a straight line it would be fine, but in a corner, the direction the trailer's weight would push would be behind the contact point of the rear wheel. I think I must put the mounting point further forward.

Cheers!
 
Nope it would run in a straight line not a corner. Basically I used paint to just show the line of the bar so that you could use the additional fixing point where the cantilever breaks normally attach.

framejig.jpg


That way you have 5 load bearing points, the central being the stronger as the 4 you are currently using are not designed to take the horizontal loads which you will be forced on them when pulling a trailer.
 
Nope it would run in a straight line not a corner. Basically I used paint to just show the line of the bar so that you could use the additional fixing point where the cantilever breaks normally attach.

framejig.jpg


That way you have 5 load bearing points, the central being the stronger as the 4 you are currently using are not designed to take the horizontal loads which you will be forced on them when pulling a trailer.

Now that is a nice drawing :thumb:

I was not dissing your drawings, I was just funning you, and your point is very clear, thanks for the input! :D

I do not wish to use the bridge, where a fender or canti brakes would be, as I was told by Charge Bikes that this would fail if used for a hitch mounting point.....

Charge Bikes said:
Hi Stuart,

Many frames may fail with the load attached there. Our frames when tested are not subjected to loads with direct mounting to the bridge.
Rack loads are taken down to the rear axle. I would not suggest fitting it to the bridge and keep the seat post arrangement.

Now honestly I do not know if the were thinking that I was planning on using ONLY the bridge as a mounting point or not, but I figure that four points on a solid rack should be enough.

I want the pivot point at the rear axle or ahead of it, NOT behind it.

This is what my set up looks like now......

cannondale_hitch_pivot_1.jpg

The yellow line is the pivot point, as you can see it is well ahead of the rear axle. I have carried some very heavy loads and I've had no problem with handling, even down some fairly steep hills at speeds I should not have gone (over 40 Km/h!!) As I know this works, want to stick to it, or near it.

Some work got done today on the rack....

Mixer_8_Rack_done_1.jpg


Mixer_8_Rack_done_2.jpg


Mixer_8_Rack_done_3.jpg


I think this should be a very skookum rack :D

Now a question, do you think I should put a 3rd strut on the rack...?

Mixer_8_rack_3rd_strut.jpg

I guess it would just make everything more balanced and it certainly cannot hurt with the strength of the rack and hitch....???

I will put a "Pannier Rail" on each side of the rack....

Mixer_8_rack_pannier_rail.jpg


This will let me put the panniers on and have enough heel clearance as well as keep the panniers lower to the ground for better stability.

On to mounting the hitch...........
 
The piece of cardboard in the pics below, would be a steel plate, welded in place, with a 1" in diameter piece of steel, maybe 1" long, welded onto the bottom of the plate, there would be a hole through the plate and the steel below the plate, which would accept a removable stud that would have the hitch on it. This would make it removable so I could use the rack, without the trailer, and it would allow me to raise the mounting point to the existing height I am using now, so I don't have to do major surgery on the trailer again.

Mixer_8_rack_hitch_mounting_plate1.jpg

In this pic the mounting plate would be directly above the rear axle.

Mixer_8_rack_hitch_mounting_plate2.jpg

In the second option, the mounting point would be forward of the rear axle, very much the same as the set up I have now with the Cannondale.

I think I'll go for the forward mounting position, as the handling of the trailer now is fine, good in fact.

Mixer_8_rack_hitch_mount_stud.jpg

This is kind of what I'm thinking about for a removable stud, it would have to be very solid and maybe one hole is not enough, maybe I'd make it with three holes and somewhat gusseted?

Comments?

Cheers!
 
Nice wheel

Is that a custom build? And what is that around the cog, something to keep the chain from dropping and how do you tension the chain with the verticle dropouts, is there an eccentric BB?

I hear you on the workin too much! Wish I could have a beefy rack like that, but I do have access to a welder so I guess I need to hone my skills more and do it myself:D
 
Is that a custom build?

No, it is a "2010 Charge Mixer 8" :D

ProRaceMechanicAnd said:
what is that around the cog, something to keep the chain from dropping.......
More like something to keep stuff from getting caught in the chain, kind of a guard I guess...?

ProRaceMechanic said:
and how do you tension the chain with the vertical dropouts, is there an eccentric BB?
Yep, I've only had a look at it, no intention of messing with it for a while anyway :rolleyes:


ProRaceMechanic said:
I hear you on the workin too much! Wish I could have a beefy rack like that, but I do have access to a welder so I guess I need to hone my skills more and do it myself:D

Yep, welding is a skill you need to work on all the time, on a build like this, I might spend an hour just welding up little bits into piles of steel for an hour, just to get back to steady welding. Even so, I usually end up grinding and rewelding stuff to get to where I'm happy. A #120 flap sanding disk is also a wonderful thing to have, it hides a lot of boo-boos :eek::rolleyes:
 
I got some more work done on the rack, I did decide to put a third strut on the rack, and I got the pannier rails done too.....

Mixer_8_rack_pannier_rails_2.jpg


Mixer_8_rack_pannier_rails_1.jpg


Mixer_8_rack_pannier_rails_3.jpg

This will allow me to use the panniers even with the trailer in tow, I won't be able to use the top of the rack but I think that is OK.

I will make up some sort of attachment, a stud for lack of a better word, that will mount on top of the rack to attach the trailer to, it will become the hitch I guess.

Mixer_8_rack_removable_hitch_1.jpg


Mixer_8_rack_removable_hitch_2.jpg

Just playing with ideas here.

One thought I had was to make something that hooks around the cross bars on the rack, and then is held in place with one bolt big knob. This would allow me to easily remove the hitch from the rack if I wish, but would also be a very solid mount for the hitch.

More on that tomorrow, it's 3AM and I need to get some sleep!

Thanks to everyone who has commented on this build, it is really great to hear all of the various ideas, it makes me think :thumb:

Cheers!
 
Just about got it done :D

Mixer_8_finished_rack_1.jpg


Mixer_8_finished_rack_2.jpg

That is the rack, basically finished, I might add a few bungy point on it, and do a bit more sanding on some of my rougher welds :eek: but that is about 95% done.

Here it is with the hitch attached....

Mixer_8_finished_rack_hitch_1.jpg


Mixer_8_finished_rack_hitch_2.jpg

.... I'll not lie, this is NOT lightweight in any way, but I think it is rather skookum, that is solid and durable. :thumb:

The hitch is held in place with two 10mm bolts, with hand knobs on them......

Mixer_8_removable_hitch.jpg

The knob nearest the seat is a bit long, I'll drill a hole in near the top of it and put a small padlock on it, to prevent theft.

Cont ..........
 
.........

Here is the Mixer 8 and the trailer.....

Mixer_8_finished_rack_hitch_trailer_1.jpg


Mixer_8_finished_rack_hitch_trailer_2.jpg


and soon after that, I took the new set up on it's maiden delivery.....

Mixer_8_finished_rack_hitch_trailer_1st_delivery.jpg

That is about 60Kg/130lbs of weight on there, a medium load. Things were great, it handles like a dream, the new bike is very responsive!

I now need to get some clip-less pedals, and a kick stand.

The kick stand may be a bit of a problem, I want the bi-pod stand like I have on the Cannondale, but the area just behind the BB on this bike is quite small, so I don't know if it will fit, might have to get out the grinder and make it fit, as I really want that bi-pod stand.

Next up will be some paint, but I'm thinking of trying to find some company to galvanize it, I think that would be very cool, it would really complete the whole thing, it should look good and it should also not rust as soon as a chipped paint version would.

I said I know this is not lightweight, and it isn't but I think it should last, the weak point now is going to be the frame, but it is bolted securely to four points on mounts that the maker intended to carry weight, so......?

I guess time will tell :D

Cheers!
 
Bloody amazing mate!

How about some matching tires for the trailer and possible having the trailer resprayed to match the bike?

Also Im suprised you don't have any advertisement boards on the trailer to promote the L-Shop!
 
Bloody amazing mate!

How about some matching tires for the trailer and possible having the trailer resprayed to match the bike?

Also Im suprised you don't have any advertisement boards on the trailer to promote the L-Shop!

Thanks!

Yeah, I've been thinking about some signage :cool:

I think I'll leave the trailer red, that way I hope the stupid peds can see it and not step on it, or trip over it..... yeah right.... :rolleyes:
 
Back
Top Bottom