The Long John Prototype
Bike completed: July 2001
I'm fascinated by load bikes and the ability to carry huge objects on human powered vehicles. You can see this in my various moving house pages - leaving Mark's place, to Rich St and the CANC experience . Somehow I arrived at the decision to build a long john type bike, using a few pictures off the net as the source for my ideas.
As usual, I started with a donor bike and began by cutting it up. The plan was to push the seat back over the rear wheel a little bit to keep the wheelbase from getting too long. The limit here is that the front of my shoe can't hit the load space. Ideally the handlebars should be directly above the forward limit of the pedal stroke. This also let me add a little ground clearance, putting the bottom bracket about 250mm off the ground. Unfortunately I wanted derailleur gears which meant the chainstays had to be somewhat longer than I'd like, so I used a 24 inch wheel "mountain bike" as the donor.
The rear headset was off another donor bike, cut horizontally and the parts brazed in place below the main chassis tube and between the two upright bits. I did the same with the steerer tube off that bike, allowing a standard handlebar, stem and bearings to be used.
The really dodgy thing is the front off the donor bike just brazed onto the 50mm square tube. That was no stronger than it looks, giving a worrying "suspension" effect as it flexed when the bike hit bumps.
Tilting the chainstays down brought the seat tube back a long way, and as expected the ultra-long seatpost failed the first time it was used. If that had worked it would have simplified things a lot, but such is life. The second attempt was to add a spare front fork and the top off a seat tube with a new seat. I have a copious supply of dumped bikes to play with...
That seat was uncomfortable and didn't feel right, plus I had developed the need to carry standard bike panniers on it. So another rear triangle was added to the system, with a second seatpost at a more sensible angle. Having the brakes on the chainstays was more annoying than useful as they were hard to get the cable to without interfering with the pedals. Center pull brakes work fine in that position. The seat stay mounts were tricky due to the smaller rear wheel so I made a booster plate and brazed the brakes on as a single unit.
The original steering was the bent tube used by the other manufacturers, with a quick home-made universal joint at the front to cope with the odd angles involved. This universal was a bit flimsy but worked well enough for the first tests. Both steering arms were simply welded to the fork crowns. This photo was taken just before I took it up to have the bottom bracket retapped after the brazing.
Putting the load platform on was easy - I used the quick and simple approach of TIG welding mild steel tube it place which meant it was all done in a couple of hours.
The tricky bit proved to be the stand. I wanted something strong enough to be rock solid even when holding the loaded bike on a slope, and didn't want the complexity of forward-mounted stand or the risk of legs that tilt up and forward when not in use. The design I came up with is a small tube that joins the legs and acts as a pivot, with the bend in the legs added later when they proved to contact the ground too far back. This stand is slowly failing in use where the legs are bolted to the pivot. I am in the process of coming up with a better idea.
The original steering was not particularly good. I just copied what I've seen on the net, and it was a bit fragile. The universal joint at the front worried me, and I wondered if I could make something better. See the joint:
I redid the whole front end to make it stronger, using more 50mm square tubing and adding a second pair of linkages to the steering. At the same time I reduced the head angle to reduce the amount of drop. Kelly found it very hard to steer when loaded, and the new angle has convinced me that a vertical headset would work even better. The new steering is shorter as well as moving the steering completely out of the load space, but the two front pivots (headset and idler/ intermediate) slope opposite ways which is a bit hard on the very short linking rod. This limits the lock more than I'd like, as it's hard to manoeuvre in tight spaces and novice riders run out of lock while trying to balance.
To date I think the most weight it's carried is a bit over 150kg, which is more than I can ride up Sydney hills with. It's been the key to my most recent house move, and has attracted a lot of positive comment from people on the street. The photo shows a smaller load, but it's mostly books. Those bins seemed heavy but not too bad one at a time carrying them out to the bike, but two shelves worth of books gets heavy really fast on the hills.
I've been riding this as my regular bike of late, because I've been moving house and buying a lot of furniture-type stuff, as well as taking my other bike out to the trucking depot, then back home again when I discovered that they were on strike. However the successful version of that trip let me weigh the bike, at about 30kg (127kg with pannier, lock and me standing on the scales). I've also added a front derailleur which works largely because I've left the original rear triangle intact. As of August 2001 I have done about 500km on the bike, and there have been no real problems.
September 2001: problem: bike has been stolen. Because it's too large to get it inside easily, I began locking it to a lamp post outside the house. Someone came along and cut the lock...