DIY cargo trailer

Lorenzo L. Love wrote:
On Wed, 18 Jan 2006 11:24:52 -0800, wrote:


wrote:

A while ago I built my third trailer, made without welding. And this
time I did a full photo documentation as I went along:

http://drumbent.com/trailer_big.html

Cheers,
Mark


Nice.

I am contemplating building a single wheel trailer (similar to a BOB)
for carrying children. I don't like the wide unwieldy feel of a 2-wheel
trailer with such valuable cargo.

Anyone have any suggestions or tips?

Joseph


Don't. One wheel trailers are excellent for light cargo but any
movement in the trailer will be transmitted to the bike. I used to use
a BOB Coz and now use a BOB Yak and then I take my cat to the vet in a
carrier in the trailer her movement can be felt significantly. A child
doing what a child does could knock your bike around to a dangerous
extent. Two wheel trailers are more unwieldy, but more stable for live
cargo.


I don't know about that. I pulled a child for 5 years with a
trailer-bike, and have used a BOB Coz for several years also. Most of my
riding with them was/is on single-track off-road. 2-wheel trailers want
to tip, 1-wheelers don't, since they lean in the turns. The downside is
you'll feel the cargo shift since the trailer is free to flop, but I
never found it dangerous from a control POV.

Peter Cole wrote:
Lorenzo L. Love wrote:
On Wed, 18 Jan 2006 11:24:52 -0800, wrote:


wrote:

A while ago I built my third trailer, made without welding. And this
time I did a full photo documentation as I went along:

http://drumbent.com/trailer_big.html

Cheers,
Mark


Nice.

I am contemplating building a single wheel trailer (similar to a BOB)
for carrying children. I don't like the wide unwieldy feel of a 2-wheel
trailer with such valuable cargo.

Anyone have any suggestions or tips?

Joseph


Don't. One wheel trailers are excellent for light cargo but any
movement in the trailer will be transmitted to the bike. I used to use
a BOB Coz and now use a BOB Yak and then I take my cat to the vet in a
carrier in the trailer her movement can be felt significantly. A child
doing what a child does could knock your bike around to a dangerous
extent. Two wheel trailers are more unwieldy, but more stable for live
cargo.


I don't know about that. I pulled a child for 5 years with a
trailer-bike, and have used a BOB Coz for several years also. Most of my
riding with them was/is on single-track off-road. 2-wheel trailers want
to tip, 1-wheelers don't, since they lean in the turns. The downside is
you'll feel the cargo shift since the trailer is free to flop, but I
never found it dangerous from a control POV.

Most of my riding with the kids will also be on single-track. I was
figuring on a secure 5-point belt and NASCAR-type webbing to keep the
arms inside. The seating would be low with the kid's rump about 10" off
the ground. Given that the kid will be only able to move the head and
arms and within the width constraints of the narrow cage, and being so
low, I don't see how they could affect the balance that much.

Crashing would be a bad thing, but with a single wheel trailer we can
ride where our only hazards are trees, vs being stuck on roads (lightly
travelled dirts ones) with a wide trailer where we risk getting mowed
down.

Joseph

wrote

Peter Cole wrote:
Lorenzo L. Love wrote:
I am contemplating building a single wheel trailer (similar to a BOB)
for carrying children. I don't like the wide unwieldy feel of a
2-wheel
trailer with such valuable cargo.

[...]

Don't. One wheel trailers are excellent for light cargo but any
movement in the trailer will be transmitted to the bike.
[...] A child
doing what a child does could knock your bike around to a dangerous
extent. Two wheel trailers are more unwieldy, but more stable for
live
cargo.

My experience with single-wheeled trailers matches Lorenzo's. In
my opinion. it's also not just CYA tort-avoidance (though that may
be a large part) that causes BOB trailers to carry a warning that
they should not be used to carry kids. There are real design and
usability issues.

I don't know about that. I pulled a child for 5 years with a
trailer-bike, and have used a BOB Coz for several years also.

There's significant difference between a child on trail-a-bike and
a child in a single-wheeled trailer,-- both in the likely age and (self)
control of the kid, and in the effect of control on the (adult) bike.
I don't know of any trail-a-bike systems that connect to the
rear fork as do the BOB trailers.

Most of my riding with the kids will also be on single-track
[...] Given that the kid will be only able to move the head and
arms and within the width constraints of the narrow cage, and being so
low, I don't see how they could affect the balance that much.

I know from experience that as little as 45 "static" lbs in a BOB
trailer can make handling difficult on *some* bikes on *some*
surfaces at even only moderate speeds. Google for "BOB trailer
wobble" in newsgroups to see a number discussions over the
past years.

Perhaps it is possible to design a single-wheeled bike trailer and
bike attachment system that would work well for a purpose-built
child carrier intended for single-track use. Borrowing a BOB trailer
and trying some experiments with shifting contents that simulate
"live" loads would seem like a good starting point.

Jon Meinecke

wrote:

Most of my riding with the kids will also be on single-track. I was
figuring on a secure 5-point belt and NASCAR-type webbing to keep the
arms inside. The seating would be low with the kid's rump about 10" off
the ground. Given that the kid will be only able to move the head and
arms and within the width constraints of the narrow cage, and being so
low, I don't see how they could affect the balance that much.

Crashing would be a bad thing, but with a single wheel trailer we can
ride where our only hazards are trees, vs being stuck on roads (lightly
travelled dirts ones) with a wide trailer where we risk getting mowed
down.

Joseph

Helmet, roll cage, secure 5-point belt, and NASCAR-type webbing all
sounds safe enough (and I'm sure the kids will really enjoy the ride)
but why stop there? Simply weld a 55 gallon barrel to a BOB Yak
trailer, insert kid(s), and fill with polystyrene packing peanuts.

Regards,
Bob Hunt

wrote:
Peter Cole wrote:

Lorenzo L. Love wrote:

On Wed, 18 Jan 2006 11:24:52 -0800, wrote:


wrote:


A while ago I built my third trailer, made without welding. And this
time I did a full photo documentation as I went along:

http://drumbent.com/trailer_big.html

Cheers,
Mark


Nice.

I am contemplating building a single wheel trailer (similar to a BOB)
for carrying children. I don't like the wide unwieldy feel of a 2-wheel
trailer with such valuable cargo.

Anyone have any suggestions or tips?

Joseph


Don't. One wheel trailers are excellent for light cargo but any
movement in the trailer will be transmitted to the bike. I used to use
a BOB Coz and now use a BOB Yak and then I take my cat to the vet in a
carrier in the trailer her movement can be felt significantly. A child
doing what a child does could knock your bike around to a dangerous
extent. Two wheel trailers are more unwieldy, but more stable for live
cargo.


I don't know about that. I pulled a child for 5 years with a
trailer-bike, and have used a BOB Coz for several years also. Most of my
riding with them was/is on single-track off-road. 2-wheel trailers want
to tip, 1-wheelers don't, since they lean in the turns. The downside is
you'll feel the cargo shift since the trailer is free to flop, but I
never found it dangerous from a control POV.


Most of my riding with the kids will also be on single-track. I was
figuring on a secure 5-point belt and NASCAR-type webbing to keep the
arms inside. The seating would be low with the kid's rump about 10" off
the ground. Given that the kid will be only able to move the head and
arms and within the width constraints of the narrow cage, and being so
low, I don't see how they could affect the balance that much.

Crashing would be a bad thing, but with a single wheel trailer we can
ride where our only hazards are trees, vs being stuck on roads (lightly
travelled dirts ones) with a wide trailer where we risk getting mowed
down.

Joseph


Practically speaking, if you're going on single-track, one-wheeled
trailers are the only way to go. That said, given the bumpy ride, the
"window" for a trailer might only be between ages 2-4 (earliest for
off-road trailer to earliest for trailer-bike), so I don't know whether
it's worth the effort.

I pulled my daughter from age 4 - 9, a weight change from perhaps 40-90
lb (reaching the limit of the trailer-bike spec.). The trailer-bike had
a u-joint seatpost mount as opposed to the BOB's rear axle attachment.
The t-b (Adams) always had a significant amount of play in the joint,
allowing it to "flop". As my daughter got older and heavier, the flop
had more effect on balance, but she got much better at balancing
herself, so flops became rare. Part of the equation is the ratio of
parent to child weight, I'm sure. I'm a big person (6'10", 235), I'm
sure a smaller person would have more difficulty with control.

The low CG of the BOB is nice, but I have caught it on rocks/logs a
couple of times, once tossing myself over the bars when I came to an
abrupt stop. The structural members of my BOB are significantly bent
from frequent collisions. Likewise, the trailer-bike's pedals and
chainrings got smashed a few times.

I never crashed with my daughter (100's of rides). You have to be
careful not to weave too close to trees and the combination rig has a
tendency to jackknife, especially on soft surfaces with too much front
brake. On the plus side, the tongue weight completely prevents endos on
the steepest trail descents. I've never had wobble with either trailer,
at any speed.

I would think of a DIY as being a sketchy proposition though,
particularly with hitch design/fabrication. Some of my friends expressed
concern over the kind of riding I did with my child, and I admit to the
occasional second thoughts. I had a few data points such as the Adams
design being used on tandem trailer-bikes with heavier loads. Even being
an engineer, I'm not sure I'd have the confidence in my own design/build
skills to trust my kid's safety to them (or I'd so over-engineer it'd be
a pig).

I could see buying a BOB and using it as a platform to mount a child
seat. It probably wouldn't be any less safe than a lot of the
contraptions people carry children with, but on singletrack, with such a
small rear wheel, the ride would would be dangerously harsh for a
toddler. I'd just wait for trailer-bike age. Although I did less of it
than the woods, we took the trailer bike on city streets many times,
even negotiating busy downtown (Boston) loops. The agility of the
trailer-bike works very well in those conditions.

From what I've read, the seatpost is not the best place for attaching a
trailer (though it is easier to concoct for the homebuilder).

What happens upon sudden braking is that the unbraked trailer keeps
pushing ahead into the bike. If it's mounted to the seatpost it can
tend to push the bike either up, which is not good if it actually
causes the rear wheel to lift, or push sideways, which is not good if
you're trying to maintain control.

As Peter has stated, his size and weight would probably resist most
efforts the trailer and cargo might make to influence the bike with
this design. But for anyone smaller / less weighty the seatpost hitch
seems to be a risky idea. That's why you no longer see them on
commercially-built trailers. it's much better to keep the attachment
point down low, but more difficult to make a good hitch design for that
by yourself.

Mark

Bob wrote:
wrote:

Most of my riding with the kids will also be on single-track. I was
figuring on a secure 5-point belt and NASCAR-type webbing to keep the
arms inside. The seating would be low with the kid's rump about 10" off
the ground. Given that the kid will be only able to move the head and
arms and within the width constraints of the narrow cage, and being so
low, I don't see how they could affect the balance that much.

Crashing would be a bad thing, but with a single wheel trailer we can
ride where our only hazards are trees, vs being stuck on roads (lightly
travelled dirts ones) with a wide trailer where we risk getting mowed
down.

Joseph

Helmet, roll cage, secure 5-point belt, and NASCAR-type webbing all
sounds safe enough (and I'm sure the kids will really enjoy the ride)
but why stop there? Simply weld a 55 gallon barrel to a BOB Yak
trailer, insert kid(s), and fill with polystyrene packing peanuts.

Regards,
Bob Hunt

The view would be lousy!

The idea is to make it safe enough to be able to go fast enough for it
to be fun, in an amusement park sort of way.

Joseph

Peter Cole wrote:
wrote:
Peter Cole wrote:

Lorenzo L. Love wrote:

On Wed, 18 Jan 2006 11:24:52 -0800, wrote:


wrote:


A while ago I built my third trailer, made without welding. And this
time I did a full photo documentation as I went along:

http://drumbent.com/trailer_big.html

Cheers,
Mark


Nice.

I am contemplating building a single wheel trailer (similar to a BOB)
for carrying children. I don't like the wide unwieldy feel of a 2-wheel
trailer with such valuable cargo.

Anyone have any suggestions or tips?

Joseph


Don't. One wheel trailers are excellent for light cargo but any
movement in the trailer will be transmitted to the bike. I used to use
a BOB Coz and now use a BOB Yak and then I take my cat to the vet in a
carrier in the trailer her movement can be felt significantly. A child
doing what a child does could knock your bike around to a dangerous
extent. Two wheel trailers are more unwieldy, but more stable for live
cargo.


I don't know about that. I pulled a child for 5 years with a
trailer-bike, and have used a BOB Coz for several years also. Most of my
riding with them was/is on single-track off-road. 2-wheel trailers want
to tip, 1-wheelers don't, since they lean in the turns. The downside is
you'll feel the cargo shift since the trailer is free to flop, but I
never found it dangerous from a control POV.


Most of my riding with the kids will also be on single-track. I was
figuring on a secure 5-point belt and NASCAR-type webbing to keep the
arms inside. The seating would be low with the kid's rump about 10" off
the ground. Given that the kid will be only able to move the head and
arms and within the width constraints of the narrow cage, and being so
low, I don't see how they could affect the balance that much.

Crashing would be a bad thing, but with a single wheel trailer we can
ride where our only hazards are trees, vs being stuck on roads (lightly
travelled dirts ones) with a wide trailer where we risk getting mowed
down.

Joseph


Practically speaking, if you're going on single-track, one-wheeled
trailers are the only way to go. That said, given the bumpy ride, the
"window" for a trailer might only be between ages 2-4 (earliest for
off-road trailer to earliest for trailer-bike), so I don't know whether
it's worth the effort.

I pulled my daughter from age 4 - 9, a weight change from perhaps 40-90
lb (reaching the limit of the trailer-bike spec.). The trailer-bike had
a u-joint seatpost mount as opposed to the BOB's rear axle attachment.
The t-b (Adams) always had a significant amount of play in the joint,
allowing it to "flop". As my daughter got older and heavier, the flop
had more effect on balance, but she got much better at balancing
herself, so flops became rare. Part of the equation is the ratio of
parent to child weight, I'm sure. I'm a big person (6'10", 235), I'm
sure a smaller person would have more difficulty with control.

The low CG of the BOB is nice, but I have caught it on rocks/logs a
couple of times, once tossing myself over the bars when I came to an
abrupt stop. The structural members of my BOB are significantly bent
from frequent collisions. Likewise, the trailer-bike's pedals and
chainrings got smashed a few times.

I never crashed with my daughter (100's of rides). You have to be
careful not to weave too close to trees and the combination rig has a
tendency to jackknife, especially on soft surfaces with too much front
brake. On the plus side, the tongue weight completely prevents endos on
the steepest trail descents. I've never had wobble with either trailer,
at any speed.

I would think of a DIY as being a sketchy proposition though,
particularly with hitch design/fabrication. Some of my friends expressed
concern over the kind of riding I did with my child, and I admit to the
occasional second thoughts. I had a few data points such as the Adams
design being used on tandem trailer-bikes with heavier loads. Even being
an engineer, I'm not sure I'd have the confidence in my own design/build
skills to trust my kid's safety to them (or I'd so over-engineer it'd be
a pig).

I could see buying a BOB and using it as a platform to mount a child
seat. It probably wouldn't be any less safe than a lot of the
contraptions people carry children with, but on singletrack, with such a
small rear wheel, the ride would would be dangerously harsh for a
toddler. I'd just wait for trailer-bike age. Although I did less of it
than the woods, we took the trailer bike on city streets many times,
even negotiating busy downtown (Boston) loops. The agility of the
trailer-bike works very well in those conditions.

The whole point is to open up new possibilities for rides with the
kids, who are of varying ages and cycling abilities. A trailer that was
"cool" and was enough fun that other kids would even want to try is the
idea. My kids like action and speed, so I want to give it to them for
as long as I can, til the day comes when I can't keep up with them
anymore.

The main issues I have thought about so far are stability, and
survivability. A crash isn't that big a deal if everyone is well
protected, and there is no danger of being run over by a car. I was
figuring on some sort of dual ball-joint type of flex coupling, mounted
on some sort of bracket to the back skewer, or clamped to the stays.
The idea is to have some adjustability to be able to tune the
stability, and ball joints so as not to have any slop/flop. I built a
few race car suspensions a million years ago, and no one got killed, so
I'm not too worried about building a robust trailer. A strong
bash-gaurd/skid plate was also something I planned on so as not to have
the whole contraption get caught on a root or something. I was also
thinking about using a suspended 24" wheel.

Joseph

wrote in message
ups.com...
A while ago I built my third trailer, made without welding. And this
time I did a full photo documentation as I went along:

http://drumbent.com/trailer_big.html

Cheers,
Mark


Nice. I want to build one to haul my dog around.

My friend is not using the trailer at the moment, since she has not yet
become a winter cyclist (making it handy for me to borrow back until I
build my own). But once she starts using it in the Spring we plan to
get photos of her towing her dog in it.

Mark