Megatrailer

Completed: Jan 2000

Update August 2007: Megatrailer is still around. I've more or less donated it to Bike Club because that way more people use it. I had to replace the chain in the hitch earlier this year, but other than that it's still going strong. I have still got a list of new features for it, but until it does those won't happen. basically, better dropouts when it's in flat-top mode that hold onto the wheels better (the originals are too shallow and really need lawyer lugs because they're at a bad angle), and recess the dropouts when it's in big-load mode so they don't poke up into the flat-top area. I might be able to do some of that once I get a welder again, but recessing the dropouts really means spreading the side bars. But I might fake it by moving them onto the uprights, making the trailer bed lower by 50mm, but that will mean it hits the ground more easily on bumps. perhaps have both.

Before I built my tandem trike I decided that a good "starter" project would be a decent bike trailer that would also help me get the tandem bits back to the workshop. I could learn to braze and get some idea of how heavily stressed brazed joints behave. As it happened I used a van to get the tubing because it was more convenient (ie, Ken offered to go and get it rather than me taking a day off work). The design is a giant version of Ken's standard trailer, like the one I built later for Kelly. The rectangle is 1050mm wide and 1500mm long, and the towing arm is long enough to allow for a 27" wheel with mudguards. It's all made of galvanised steel tube with a wall thickness of around 2mm. I have a wooden platform that fits it, but this doubles the weight of the trailer so I only use it when I have to.

I decided to put the vertical arms on to strengthen the load surface via the reinforcing rods, and to hold an extra set of dropouts allowing the trailer to be flipped over into a flatbed configuration. That would help to realise my ambition of being able to move house by bicycle. In practice that's still quite hard, as putting a bed on the trailer makes it very, very hard to stay on the bike. The trailer is heavy enough that it lifts the back of the bike off the ground when going up kerbs, so I prefer to use a trike for towing beds. Towing several adults is quite possible, and it comes down to how hard the towing vehicle is willing to work.

I also managed to get that very heavy-duty wheel off an old load bike, and the lawyer lugs turned out to be a very good idea. On CANC we hit a bump with the trailer up the other way and lost both wheels, largely because the support rods interfere with the "top" dropouts and stop the axles going in as far as they should. I've now started using wheel retention tricks on all my trailers, on the theory that they don't get checked over very often and it's even less often that I take the wheels off.

The towing arm is pretty simple on a trailer this wide, and has proved strong enough to cope with some fairly silly behaviour - people walking on it while the trailer is moving for example. This design also means that the flatbed mode attaches to the derailleur side of the towing cycle, which can be a problem for many bikes. The tandem trike has custom towing points behind the rear wheel, and I've put a similar thing on the rack of my long bike to get around the problem.

Attaching the trailer to the cycle uses Ken's spring and chain technique, detailed on the shopping trailer page. For a trailer this big I've decided that a more rigid hitch would actually work better, as the oscillation from pedalling can make the load bounce in a most irritating way. So I may put a universal joint or something in there instead, but I haven't seen one that I like yet so I'll put it off for a while yet. The tab on the front is 3mm thick chrome-moly steel and is about 40mm wide at the point where it's bent. That should give some idea of the loads it experiences.

Here's a shot showing what happens with a heavy load on the hitch - it bends quite a long way. You can imagine how this reacts when I try to pedal or brake...

As yet I haven't managed to break the trailer, but I have broken an axle in one of the wheels. The trailer has been used to move house (four times), carried a variety of shelving units and went on CANC with me (where it was used as a roof rack for three months and only did about 250km on it's own wheels). It also carried the band through Broome, as you can see in the photo above, and carried a cameraman on Critical Mass (where I discovered that four adults can, and will, climb on it).