There's always room for improvement in any design, and this is the first draft. Please get in touch if you have any ideas to make it better, cheaper, easier to fit or more attractive to drivers.
Practical trials with a tame cidomo driver or two would help a lot with all that, if you know a driver who would like to try one out please get in touch .
The rear half metre or so of the bamboo rods are attached along the top edges of the cidomo roof by screws, tie-wraps or clips of some kind and secured at the front end by string or bungee cord tied between the ends of the bamboo rods and the ends of the wooden struts the ponies stand between.Keeping Tension
The sail would be tensioned by the mountings on the roof and the cord tied to the wooden struts.
The front end of the sail is narrower than the struts, so the cords would make the fabric taut laterally and the poles taut vertically and laterally; so in theory the whole assembly shouldn't wobble around much.Snagging
The sail and poles would stay pretty much within the bounds of the cidomo and pony as it were, so should be clear from snagging on vertical obstacles like walls and fences.
Overhanging branches, guttering and other miscellaneous danglements could be a problem, the fabric would be fairly hard-wearing but there's a risk of tearing the sail if the driver powers through an obstacle as they might normally with the roof of their cart.Visibility
One of the horrific daubs is a mock-up of a view out of the front of a cidomo from the driver's perspective. Visibility should be fine, no problem seeing forward or to the sides.Weather
The fabric would need to be dense enough to provide shade but not let puddles form in the rain, the water would ideally seep through without puddling and making the sail sag. In super-heavy rain, shade isn't a problem for the ponies anyway so the sail could be stowed, as it would be in high winds.
A third bamboo pole between the two front ends of the sail would better protect the sail from stray branches and other obstacles, and ensure the front end was taut but would add a little to the to the cost and complexity, plus make it less easy to remove the sail for cleaning or replacement.Quick Release
Perhaps the poles could be attached to the roof of the cidomo by attaching a half metre hollow bamboo tube of a wider bore and the longer poles slotted into them for easy removal in rain and high winds etc, means more bamboo and cost etc. but perhaps more practical.Side Panels
It could be designed with short vertical sides to provide more shade on the sides both early and late in the day but it'd make the assembly more complicated, require more of the most expensive ingredient and be more prone to tearing etc. It'd also obscuring the view of the driver so probably not a great idea.
The bamboo poles would be tricky to get in a car, which could be a problem, and would be a bit of a liability on a scooter but super-easy on a boat. They would weigh very little.Assembly
They're probably best assembled where they will be fitted, they could be put together elsewhere and then the poles wrapped with the sails and cords but there's the risk of the sails being ripped in transit rather than more safely transported in a bag.Fitting
Fitting should be a doddle, maybe 15 minutes tops to put one together and attach to a cidomo.
Two of them, each about 2.5m long, thick enough to be slightly flexible at one end when anchored firmly at the other but not wobbly, they need to keep the tension of the whole thing and not be waving around in the wind.Fabric sail
A trapezium shaped porous fabric sail with tunnels sewn down the two long edges to fit the bamboo poles, with the tunnels open at both ends.
The sails would be of a plain, hard-wearing, easily washed, quick-drying slightly porous fabric, in a colour not too dark to look awful with sun bleaching but not so light that they look dirty after 10 minutes.Fixings
String or bungee cord to tie the front ends to the cidomo struts on either side of the pony, which keeps the front of the sail taut both vertically and laterally.
Screws, clips or tie-wraps to secure the rear ends of the bamboo rods to the roof at 3 points on each side.
It's super-low tech and intended to be easy to fix up or replace parts if something breaks.
Bamboo is pretty cheap to replace if broken.Washing & Replacing
For washing and replacing, the sails can be slipped off the front end once the strings or bungee cords are untied.