Part 2: Home-built Xtracycle/Big Dummy seat

Seatbelt magic resides in the holes.

We left off last time with a more-or-less finished deck seat assembly. I used the seat as it appeared in that last post for over four years without an integrated seatbelt system. Instead, I used a length of one-inch wide utility webbing and an adjustable buckle purchased from REI; something very similar to, but not quite exactly like this. I ran the webbing under both v-racks (over the rear fender), with each end of the webbing coming up behind each side panel of the seat deck assembly, then over her lap with the buckle in the middle of her lap. My eldest daughter was three years old when she started riding in the seat, and this configuration worked fine for her at that age. Yet, I always thought there was room for improvement.

A piqued interest of my youngest daughter in riding the Big Dummy recently hastened seatbelt improvements. She is now about 15 months old, and although she has enjoyed riding in our old Burley trailer, she wants to do what the big people are doing and has very recently become very energized about riding on the Dummy. She did a few rides with the old seatbelt system, but it seemed that a five-point harness was in order.

I didn't want for screw heads or other hardware protrusions to stick out of the areas where her body would be in contact, so I devised the following system using easy-to-source webbing and Fastex-type fasteners. There is perhaps some detail missing below, but this is a new development and still in the process of being honed. As I get it dialed in, I'll post more photos.

Here we go. I used a one-inch diameter drill bit to make holes through which I inserted 3/4-inch webbing. Note that I would have preferred to use one-inch webbing, but 3/4 was what I had on hand. depending on how things work out, I may reconfigure the webbing, which shouldn't be a big deal. In any case, the procedure follows.

Pilot holes first. For the shoulder straps, I drilled two holes six inches apart on center, centered across the backrest. Each hole is 2 1/2 inches down from the top of the backrest. 

After drilling the pilot holes, I drilled with the 1" bit part of the way through the back...

...and the rest of the way through the front so as not to rip up either the front or back face of the wood upon exit.

For the seat belt, I located the hole center about 2 1/2 inches above the deck surface, centered laterally on the side panel. Same drilling procedure as above. 

After the holes were drilled, I sanded and smoothed their edges to reduce the potential for wear on the straps. Next came installation of the straps. I used some 3/4-inch nylon webbing that conveniently already had buckles installed, with one side adjustable and the other side fixed. Three sets of webbing and buckles are needed, as are 2 Fastex-type three-bar sliders, 1 D-ring, and 1 snaphook. First the seatbelt.

Sorry for the photo that doesn't quite focus on the seatbelt, but hopefully the threading pattern is clear. The goal is a snug fit at the passenger's hips, just below the iliac crest; not at the waist. A webbing/buckle combo is shown in the foreground. 

This is just a reference photo, showing a three-bar slider. These are used to attach the webbing with the fixed side of the buckle to the shoulder strap holes. I made sure to configure any non-smooth or hardware side of the strapping system away from body contact with the passenger.

The anchor strap for connecting the shoulder harness to the deck passes between the legs of the passenger. It's necessary for it to be quite secure. I could have opted to use a hole-based system as with the other straps, but instead I used a bolt. Based on some measurements and test fittings, I drilled a hole 6 1/2 inches back from the nose of the deck. I fastened stainless steel hardware, in this order from the top down: bolt, flat washer, webbing (two ends of a simple loop doubled over with the d-ring at the apex of the loop, and with holes pre-drilled for the bolt), wooden deck, flat washer, lock washer, nut. This will make more sense with the following photos.

Drilling the anchor bolt hole. Anchor bolt is in the foreground.

Anchor strap installed. Note the position of the d-ring. It's easiest to drill the webbing when it is sandwiched between two scrap pieces of wood. Making the anchor strap adjustable might have been nice, but is not entirely necessary.

Underside of the anchor bolt.

I measured and cut a slit in the foam pad through which to work the anchor strap.

Everything in place, but yet to be adjusted. The Fastex snaphook clips to the d-ring, and has a length of webbing running through it. Each end of this piece of webbing has the adjustable side of each of the the two shoulder strap buckles. The two three-bar sliders are at the top of the backrest, holding the shoulder straps to the backrest. 

A view from the back. Note the back of the seatbelt runs behind the seat, and the shoulder straps loop through the backrest. The goal of no hardware protruding into the passenger space has been met.

The first ride with the new strap system. It apparently gets a thumbs up. Note that I left the straps long for adjustment. Once they're dialed, I'll trim them. The handlebar holds a bell and a bottle cage; both well appreciated by diminutive co-pilots.

Hopefully, this presentation has made some sense and is not too difficult to follow. I can affirm that there will be at least one more installment of this series, with some more detail and updates regarding the strap system, among other things.

If this all seems like a lot of effort, well, it is to a degree. However, I personally consider the ability to safely carry passengers the defining element of my Big Dummy experience. Carrying kids and cargo has radically reshaped my biking life and made for some of the best times I've had on two wheels.

Part 1: Home-built Xtracycle/Big Dummy seat

The rear seat as it has evolved after a few years and thousands of miles of use.

For a while, I've been meaning to put together a post showing how I built a kid seat for the deck of my Big Dummy. The thing is, I built it prior to the existence of this blog, so it was not well documented, and factor that by my inherent laziness. That 'while' has now stretched out into a couple of years. However, recently the rusty gears in the task completion part of my brain have been jarred loose, in no small part because fellow Daddy and Big Dummy owner bikewRider has inquired as to its construction. He is in need of a means to transport his little wRider, and, not too far down the road, a second co-pilot still in development.

That said, this presentation is for entertainment purposes only. I make no claims as to the safety or reliability of the cobbled together device pictured here, nor for the appropriateness of any use thereof. I am at best a middling craftsman and have been known to use materials and resources for purposes other than that for which they were originally intended.

If, against better judgement, you proceed to construction of something similar, any outcome, whether good or bad, is entirely of your own doing. I assume no responsibility. Know this: a healthy dose of common sense and constant attention to the safe operation of any machinery is paramount. You have been warned; proceed at your own risk.

Another view of the seat.

On to the show. This is Part 1 of what will likely be two, or if I get ambitious, three parts. The focus of Part 1 is to show how everything goes together. There are a total of four wooden elements in the following construction: 1 deck, 1 backrest, and 2 side panels. A key element that allows the deck to support a vertical backrest are deck wings. Don't worry, they'll become apparent in the following photos.

The underside of the deck, removed from the v-racks. The deck wings protrude from each side. Note that the Xtracycle Magic Carpet cover  doesn't interface well with the deck wings. That part at the top is for a second seatback that I added after initial construction. Just forget about it for now. We'll come back to it at a later date.

Side view of how the deck wing supports the side panel.

I added a bit of lateral curvature to the backrest. It's constructed of two 1/4" pieces of cabinet-grade oak plywood laminated together. I glued and clamped them to a form in order to produce the curve. 

From left to right: Magic Carpet cover, closed cell foam pad, seat deck assembly.

The basic shape of the deck and the SnapHook holes are traced from the standard Xtracycle Snapdeck. Again, the deck is comprised of two laminated  1/4" layers of cabinet-grade oak plywood. I used four Xtracycle SnapHooks for attachment. If I were to do it again, I'd use the newer SuperHooks, which were not available at the time.

Another view of the deck assembly. I would have preferred maple or ash to the oak, but it was what was available.  

Here's the assembly on the bike without the Magic Carpet. Notice the backrest is above the deck so that there is space to clear the closed cell pad. Note the side panels are from scraps of exterior-grade 3/4" treated plywood, not the laminated oak of the deck and backrest.

The backrest rises to about 12" from the deck. If I did it again, I'd go to 15 or 16 inches to better support sleeping, bobbing heads. I might also make actual armrests on the side panels. My philosophy was to keep everything smallish, so as to retain maximum usefulness of the deck without a passenger. However, a little larger wouldn't diminish any utility. 

About 10.5 inches across the back. This width seems good for a wide range of differently sized passengers.

Wingtip to wingtip is about 12" on the leading edge. I traced the original Snapdeck on some paper and sketched in the  deck wings, then transferred the design to the oak plywood for cutting. I based most of the dimensions on careful guesswork and measurements of various kid-sized devices with seats. 

The trailing edge of the wings are narrower, so that the effect is that the seat sides open toward the front. Note that the strap shown serves to more strongly connect the deck to the v-racks. 

I glued and screwed the backrest to the side panels, being careful to pre-drill pilot holes and apply glue to the screw threads. That sucker is there to stay. The backrest makes a great sticker board.

A view of the deck wings. Three glued screws per side. I think all the screws that I used were 1 5/8" exterior grade.

This shows the laminated layers of the deck. I cut each layer separately, glued them together, then sanded them evenly along the edges. A router to round the edges would have been nice. 

The length of each deck wing corresponds with the width of the side panel. I angled the side panels at about 10 degrees, so as to make the backrest a bit more comfortable than a right angle would have been. If I were to do it again, I might go for a 15 degree lean. My compound mitre saw was helpful for making these cuts.

Side panels are about 9" high. 

An overall shot with the ruler to show how far back the backrest is placed.

That's more or less it for the basic construction of the deck assembly. Pretty straight forward; just measure and cut carefully, and if in doubt, build a cardboard mockup. After the initial assembly, I sanded off any rough edges and applied four coats of exterior grade polyurethane to all surfaces. After four years of a lot of use and spending a fair amount of time outside, it's holding up well, but could benefit from a refresher coat or two.

Next up: Seat harnesses and cockpit amenities.

Ride to school

Last week we missed the official national bike to school day because of work-related obligations. So we rolled the clock forward to today. We don't really put much stock in a single annual bike to school day around here, so there will be many more bike to school days.

Mother's Day recap

Julie and the girls at the park.

It's been a busy week already with no letup in sight, so I'll make this brief. This past Sunday, we had a nice day of riding and relaxing, and of course a little more riding. In between, we were able to fit in some little stints of food and fun. They weather could not have been more perfect, and we are all ready for Spring to finally do its thing. Here are a few photos. Enjoy!

She is now officially a very determined walker.

She's also made good friends with the Big Dummy.

We did a few circuits on our old standby dirt trail.

Daughter number one can't contain the thrill of speed...

...much like Mommy, on her new-to-her Raleigh XXIX dirt machine.

Daughter number two got a taste of off road riding on her newly reconfigured Big Dummy rear seat. Details of the construction coming soon.

After our first ride, we went home for some much needed lunch and napping. During the down time, I worked on my Mom's bike so that we could take another ride in the evening.

My Mom's trusty c. 1984 Univega Rover Sport. A very solid bike that will be going strong for years to come. 

Out of focus shot of my Mom on the Univega.

For our evening ride, both girls rode on the back of the Dummy. They really seem to enjoy riding together.