I now have had my Tour Easy for about 4 weeks and 400+
miles and I am falling in love with it. It is the fastest
'bent I have owned. So, of course, I wanted to make it
faster. I decided to construct a tail box. I didn't have
a supply of Coroplast so I went another direction. I have
uploaded a series of pictures to PhotoPoint (URL below)
and I would like to invite comments about the box. Since
this is my first attempt I will probably make another,
and hopefully better, box. I would like to know if the
shape, length, etc. could be improved. http://albums.photopoint.com/j/ViewPhoto?u=1025520&a=7567883&p=26026136
The construction of my box involved the use of 1/8 x 1/2 " Alum. flat stock, except for the strip connected directly to the rear rack. This is steel for the added strength and better fatigue resistance. I used 1/4" hardware cloth for the shaping and to this I glued Vinyl cloth using a spray adhesive. The lid was made the same way. The finished box weighs about 4 1/2 lbs. Would a Coroplast box weigh less? I feel that I have increased the speed of the bike somewhat, but also think that it could be increased even more with a better construction.
The way I make corflute tailboxes:
Assuming you are dealing with a mesh seat like a Greenspeed, and a vehicle with a rack
There are 6 parts (if I can add correctly): The two sides, the lid, a small piece for the back - these can all be 2mm or 4mm corflute; The floor which sits inside on top of the rack and a reinforcing rib around the top of the sides which the lid sits on - the pieces should be 4mm corflute.
1 - Mark out one side - grain of the corflute parallel to the ground. The grain of the corflute for the lid and the recinforcement should run front to back. You will have a bit that fits the seat back ( full lenght of it) then a vertical section to extend to the top of the shoulders (get the rider to sit on the bike and measure this). I like to have a gently curved top (up an inch or so and then back down again) since this looks nice and means that the lid will have some tension when it is held down. There will be an almost right angle between the vertical bit and the top. The bottom is mostly flat with a gentle curve up towards the back. The length is up to you - the longer the faster but also bulkier. For a bike you may want to consider having the back sloped so that the bike can still be wheeled on the back wheel. Leave an extra inch or so at the back of the sides which you will half cut ( cut through the top of the corflute with a stanley knife then bend - the ribs will come apart relatively easily) and bend to allow the back section to attach with zip ties.
2 - Cut out that side and use that as a template for the second side.
3 - Now do a bit of triginometry - measure the distance from the shoulders to where the back of the tailbox will be = L (remember that the sides will be curved a bit). The width each side should come in is L*tan(12deg) ~=0.2*L. Hence the width of the back should be width of seat - 0.4*L Don't be tempted to bring it in more sharply or your tailbox won't improve speed. Cut out the back piece - this will just be a rectangle.
4 - Now do the floor - Measure the distance at the height of the rack from the front of the rack to where the back of where the tailbox will be. Mark out a trapezoid using the back width the front width and this length. On the sides of the trapezoid mark out a nice gentle convex curve - try to make this the same for both sides. Then mark an extra inch or so outide the sides and back for a flap for attaching the floor to the sides. Allow a much bigger flap at the front to ensure stuff stored in the tailbox doesn't get through the gap there. The side flaps will need to have darts taken out of them every couple of inches to allow the curve. You also need to take out the bits from the flaps at the corners so they can come up at right angles. Cut out the flaps and half cut the inside where the actual floor will be. NB with all these measurements you need to take into account the extra width the flaps will make.
5 - Attach the sides and back to the bike - You can attach the back and sides together first then attach the sides to the seat frame. You put the two pieces together and then make a hole through both of them to take the cable tie. The back and sides must be supported at this point since they will probably damage themselves if left to flop.
6 - Put the floor inside the sides and back and make sure it all fits properly. Adjust/make new floor if necessary. NB don't attach it yet
7 - Take out the floor and use this as a template for the top reinforcing rib. This will probably have a different length to the floor, so you'll need to figure that out - allow a little bit for the top being curved. Cut this out with flaps and darts as for the floor. Cut out the inside of this leaving about an inch of ribbing as the support for the sides.
8 - Assemble! Put in the floor and attach all the flaps, attach this to the rack with a coupld of cable ties. Attach the reinforcing rib at the top.
9 - Now make the lid. This will extend a bit down behind the seat mesh and need to have flaps to hold it on and two half cuts where it goes throught the transitions from the vertical bit of the sides at the shoulders. These half cuts will be on opposite sides of the corflute. Cut the bits that will attach to the sides out to size, but make the bit that will be the opening lid a bit oversize. Attach the lid. Then hold it down in it's closed position and cut the opening bit to the correct size.
10 - Finishing touches. A LED tail light can be screwed directly to the corflute. This will act as a hook for a loop of shockcord (a rubber band can also be used but the don't last long) which goes through the top and holds it down. Self adhesive reflective tape sticks to corflute well and makes the bike much more visible at night - use it creatively and liberally on the back and sides! You will want a bungee cord or two inside the tailbox going around the rack through the floor to hold your luggage securely - if you just leave things knocking around they will rapidly destroy the tailbox.
You can adjust the basic method to allow attachment to other types of seat. If you don't have a rack you can fashion a support out of a strip of aluminium. You can make a bottom for it which will improve speed a little bit and stiffen up the bottom of the t-box - just trace it out and attach with flaps. You won't need too many cable ties - I think one every six inches or so it OK, add more if you think they are needed.
Thursday, 29 January 2009