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Friday, July 27th 2007

14:06

Gear Shifter Modifications

As mentioned in our 23 July 2007 diary entry, we have decided to carry out a modification to our Rhoades Car 4W2PCP quadracycle.

We don't take modifications lightly. Mostly we have been trying to use the vehicle as it comes “out of the box” and then see if we need really to change anything for our own use.

So far this is all we have changed on it:

> Plywood cargo rack tie-wrapped in place

> Reflector sticker kit

> Lights (one headlamp and two tail lights)

> Bell

> Seat adjuster reinforcers (0.125 2X2" steel plates)

> Slow-Moving vehicle sign velcroed to the back of our bin

As you can see these are all either legal requirements or for utility reasons.

After about four months of use and probably 1000 km on the road we have decided to move the gear selectors for the right seat so that they can be operated by the person sitting in the right seat.

From the factory they come with all four selectors (for both seats) mounted just below the steering column and they only accessible by the person sitting in the left seat. This means only the person sitting in the left seat can do the shifting.

As we have discovered there are some reasons that this is not optimal:

  • The left seat person can have a pretty high workload at times when cycling. As mentioned previously when starting up from a stop that goes around a curve and up or down a hill at the same time – you have to start pedaling, shift perhaps all four shifters, steer, watch for traffic and signal all at the same time. Having to shift all four sets of gears just adds to it

  • The current set-up requires the left seat person to be pretty cognizant of how the right seat person is pedalling. Unless you want to wait for them to signal or tell you that they need a higher or lower gear, then you to need to watch their feet and knees to see if they are peddling too fast or too slowly. If you always ride with the same person you can learn to pick up on their clues and shift for them, but it is easier if you don't have to. Taking new people out for a ride was difficult when they couldn't shift their own gears.

  • Giving the right seat person some autonomy makes a lot of sense. After all, the two seater Rhoades Cars feature “independent pedaling”, it just isn't “fully independent” unless each can pick their own gears.

  • It is possible that allowing the right seat person to shift their own gears will result in a higher road speed as presumably they will optimize their gear selection better than the other person guessing gears for them. It may result in better hill climbing for the same reason.

We have decided that we have enough experience on the machine to feel confident in going ahead with the modification.

The mod was a multistage process, as it was a bit complex.

  1. We looked at where the gear levers should be moved to. There is no obvious place to put them on the right side of quadracycle, so a mount had to be made. We tried sitting in the right seat in turn and seeing which location made the most sense. The conclusion we came to was that they should be in the same place on the right side where the shifters are on the left side. This gives the best combination of ergonomics and safety. We wanted a place that would give the rider the best leverage to shift, while making sure that the mount wouldn't be too much of a hazard.

  2. The design had to be simple to save weight, cost and complexity and make it easy to fabricate.

  3. The design had to provide a 7/8” tube for mounting the levers on, as this is what the shifter clamp is set up for.

  4. I made up a prototype mount from cardboard and packing tape. We tried it out for accessibility and it seems to work. Positioning it at the same location on the centre tube as the shifters on the left produced the same ergonomics as on the left side and the safety factor seems to be about the same as on the left or better.

  5. The final mount design consists of a steel 7/8” OD tube welded to a steel 0.125” mounting plate which is drilled for two 1/4” bolts, similarly to the left side mount for the steering column.

  6. I took the cardboard design to our local welding shop. They are used to me bringing in cardboard patterns for projects and don't blink when I do this now. They had the steel plate available, but I had to find the 7/8” tube at Metal Supermarkets across town. There I got a nice piece of 7/8” OD tube, 0.064” wall steel “crew tube”. The welding shop completed the project in record time – welding the tube to the plate at a 70 degree angle (20 degrees from the vertical) and then welding a cap on it to keep the dirt out. The resulting mount weighs 248g (8.75 oz) and has a 4” X 1.5” base. The tube is 7.25” long.

  7. I primed the mount with zinc chromate and then painted it gloss black. It would have been nice to paint it Rhoades Blue, but I didn't have enough paint to match that custom colour. The black will look good and make it easy to differentiate what the actual modification is when people ask.

  8. I picked up the bolts needed to mount it and also got up some black nylon cable ties, as we had to cut off many of the existing ties to move the cables from left to right.

  9. The next stage was to remove both the seats from the quadracycle and install the mount. This went smoothly as I drilled two holes in the frame tube and then bolted the mount in place with two 1/4” X 2.5” bolts, washers and plain nuts locked with Locktite.

  10. Next was moving the shifters and the cables. The shifters cannot be disassembled from their brackets and swapped left to right. Instead you must disconnect two of the four shifter cables at the de-railers and then swap the cables over. I left the top shifter on the left side and moved the bottom one to the right side, cutting the existing nylon cable ties as needed to make the swap. Then the two cables that needed to be removed were pulled through the shifters, swapped and re-installed on the correct shifters, making sure that the cables runs all were clear of the chains and without small radius turns. This proved to be fairly easy and a quick check confirmed that the gears shifted smoothly and correctly.

  11. The second last step was to install new nylon cable ties to hold the cables in place and out of the way of the riders' legs and the chains and then inspect the whole set up carefully to ensure that it works right.

  12. The last step was a test drive with Ruth, around the block.

What can I say? It works perfectly! The right seat person now has the ability to shift their own gears. Later on we will do a longer trip to confirm that it works better than the factory set-up.

In case any other owners of Rhoades Car two-seaters want to do this mod I have written a modification leaflet and photo gallery showing how to do this in step-by-step fashion, with a parts and tool list. I can also have a “right seat shifter mount” fabricated if anyone doesn't want to have one made up by their local welding shop.

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